Pub/ish«lQuarterly Celebrating the History and QlIOlity of Vocllum Tube Te Magnum SE Amplifier Da\-c Wolze rec.:nrlydesigned and built an SE amp with power and punch. Page 17 ...... Tube Review: EL·34 In one of existence since 1953 and th(Omost popular audio tubes of all time, rhe EL-34 has many variarions and performance characteristics. Page 8 Heath W-6M Heathkit: Early Tube Hi-Fi years. In This Issue .. manufacturer of Heathkit was the largest d�c Ironic kits in the US, alone time, selling over ntbe bldustry News 350 different types of kts. Learn more aboUl Check OUt the latest happen gs i in in the the early days of Heath Hi-Fi. Page 3 world of vacuum tubes. Learn the results of a recent survey of tuhe dislfih mors and sellers conducted by VIV. MU/UlrdEL-34s Harbouroudines the latest Ilem and Eric Early Cinema Sound Views. Page 15 vrv examines an early \xre�ternElectric [heater sound system. Page 24 Guitar Amplifiers Learn about how to get the best guitar tone. Chaclie Kittleson interviews Terry Buddingh, Tube Amp Expert from GuiTdrPi4yer Magazine. Page 20 Heatb w-4AM Tube Matching: Get the best soutuisfrom your amp. Matched tubes arc essential for opti mum performance from push-pull amps. n John Atwood explai s tube matching techniques for the layman. Page 22 Vacuum Tube Valleyis published quarterly for electronic enthusiasts interested in the See (Jur newfiatures in this months colorfv1 past, present and fvture af yocuum tube electronics. expanded issue W'ri!t "!ilIF, V A C U U M TUB E VA LLEY 3. Do not call, FAX or write us For Something Different-Try VTV CONTROL GRID asking for rare tubes or obscure infor V.A.L.Y.E. by Chaclie Kiuleson mation. Rart audio and guitar amp tubes are a scarce commoditv. Please do Those of )'ou interested in anothe:r nOt comaCf us asking for these tubes. unique tube-ellthusiast publication, Welcome to Issue 2 Some are a\'ailable from tube dtalers or should try VALVE. This is a tube club With our first issue, vrv ha:. �uc may be obtained by placing an ad in publicacion put out by Dan Schmalle of ceeded in getting the word out to tube Alldiolllllrt. Also, we are not the Libr.HY Poulsbo, WA. It features lots of neat ani cles on vintage hifi, tube comparisons, enthusiasts around the planet. \Vc are of Congress, so please don't call us asking striving to provide quality historical, per for a schemacic for your 1934 ReA vintage sYStem listening tests and more. formance and technical information on Theater amp. A one rear (12 issues) subscription to the vacuum tube tcchnology. Our writers VALVE newsletter is US520.00/530.00 have tons of ankles on tubes, transform Dynaco Visit to VIV Foreign. \Vhat a bargain for the useful ers, new and vintage equipment coming information you will get! R«:ently, the VTV officn were \isite:d up in future issues ofvrv. by Ra)'mond Sassoon, Executive Vice Send your ch«:k to VALVE, 1127 Presidtnt of Oynaco/Panor Corporation. Throughout the 1990s tubes will N.W Brightstat Lane, Poulsbo, WA be:gin to wander back into mainstream Raymond is very interested in bringing 98370 (360) 697-1936 audio. They arc already being seen in innovative mbe hifi products to market at reasonable prices. VTV also audi Readers - We Need Your Help!! mbe CO players, many /lew tube hifi tioned tht new PAS-4 preamp, CO-I amps, tube guirar amps and tube record \Ve are planning articles on the hbto Tube Compact Disc Player and the Stereo ing studio equipmem. Sweeten up your ry of Fisher, Harman-Kardon, Mclmosh, 80 Power Amplifier. of 0Yllaco'$ new music; put vacuum tubes in the signal All Marann, Radio Craftsmen and H.H. tube products performed very well. path! Scot! next year. If you have any informa tion including literature, history or other WriteUs Please data on these American HiFi companies We are being ove:rwhdme:d by ince� from 1947 through 1965 please send it to sail{ phone calls from tube cmhusiasts. us. Photocopies are OK. We are trying We simply cannOt handle all of the calls. to obtain the most accurate information There are three rules you should remem· possible on these companies. Also, if you ber when trying 10 COntaCt \TfV; know anyone who worked at these com panies during the Golden Era of HiFi, I. Contact US by fax or in writing help us get in COntact with them ASAP!!! only! We will not handle technical inquiries over the telephone. Please FAX A Call to Authors! or write us with your questions and we We arc also seeking quality attidn will respond if we can help you. \TrV from our readership. In particular, his FAX 408-733-6146 (send facsimile aftcr IOrical perspectives, broadcasting history, the recorded message). early recording Sludio equipmem, euly theater sound systems, speaker and equip 2. All subscription and product ment manufaCturer profiles and more. paymenu must be by check or money We will also consider technical articles on order. We do /lot lIccept credit ClIrd$. your audio, radio or eI«:tronics conSlTUC Please provide payment by bank, certi tion projects relating (0 vacuum mbes. fied, or personal check or money order Stnd us your manuscripts, along with payable in US dollars. Foreign sub schematics, illustrations and photos. scribers - be sure your payment is payable: from a US bank and is magnetically We will pay for quality articles that encoded. .lre published in vrv EDITORIAL STAFF Copyri£l1t Vocuum Tube Volley Vacuum Tube Valley is published quar 1995 All rights re$erved. terly forelectranic enthusiasts interested No port of this publicotion may be reprinted in the colorfvl post, present ond future of Charles Kiitleson Edilor and Publisher - or oIherwi$6 reproduced without written vacuum tube electronics. per' John Atwood - Technical Editor mission 01 the publisher. Subsc ipti n rote is US$25.00/yeor r o t d ial Eric Send circula ion on editor !A issues) US and US$35.00 Foreign Barbour - Associate Editor correspondence to: To subscribe, renewor change address Sieve Parr- Electronic Publishin g Consullont VTV call or FAX us at Duone u te Jerl Markiewicz -Copy Editing 1095 E. Ave., S i 106 (408)733-6146. Sunnyvole, CA 94086 USA VACUUM TUB E VALLEY • GOLDEN ERA EAR L Y HEATHK T HEATHKIT - HEATHKIT The Early HI·F] Years by Charlie Kinleson � �ulJilij "BUILD IT YOURSelF" POST-WAR HI-FI IN THE US Hi Fi for the home really gOt a boost in the years immediately aft..,f amplifier World War!I. Returning Gls gOt thelT first taste of live classical music while stationed in places like Italy and kits France. They en oyed the experience and liked what thj ey heard. But when they returned to the States after the war WfUlA.MSON HP! ro play hack such recorded erfor (A.CROSOUND r rUNSfORMf_j manees, they found most 0 the audio equipment available at rbe time IQ be mediocre at hcsr. Many of the early audio enthusiasts had military training in clec(fonics or were radio emhusiasl:S who were able ro consnuct their own amplifiers and speakers using old radio parts and war tluiUa surplus electronics and folJowins plans YOURSELF published in enthusiast publications Radio EleC/Tonics ';lleatMtt like maga7:ine. WHHA.MSON "PE Hu. ,. ,om.'oto (CHfUGO T�ANS'ORM!.j In GreaT Britain, aboul the same HIGH FIDfUT Y p",mollf;".'h' o..;, d v •• lime, similar uends were de eloping. PREAlttPLlFIER :I:�'��..!! �II""�I� VACUUM TU B E VALLEY GOLDEN ERA EAR L Y HEATH K T Peerless or SmncQr. Properly restored, FM-2 tube FM tuners. They also fea finished in gray hammerwne metallic . these amps still have excellent sound. tured the BC-I, a mono AM tuner. pamt. THE BE GI NNI NGSOf HE ATH COMPANY Edward Heath, rhe company's founder and fim president, was origi nally in the aviation and related parts bUSiness. Heath introduced rhe "Parasol,b one orchc first airplane kits in the early 1930s. Unfonunately, Mr. Heath was killed in an airplane crash in 1934.1 The second president, Howard Anthony, carried on rhe airplanc busi ness until arrer the war. Amhony was involved in aviation, but always ":I' The A-5 (1951) wa� a 10 watc am li The WI-Al was replaced by lhe W- ha a strong imcrcsted in radio and F ($49.95) 1953. tIt:!featuring a pair of 6L6s and an al 2M in This was a similar clecrronics. When the military con octal front end. Note the variable tap design, except for the use of the 5881 tracts for airplane parts dried up. ower transformer, a surplus unit. It was beam te!fode introduced by lung-Sol in Anthony decided to et into the boom p 1953. � finished in light silver hammenone. The The 5881 was a compact and ing post-war electrOniCS' business. ourput iron appears to be a potted ruggedized version of the 6L6G. It was Heath began biddin on war surplus g Chicago unit. A similar unit, the A·6, capable of more plate voltage (400+) and lots and secured millions of pounds of A-5 1952. followed the featured a old-plated control grid for aircraft parrs and declronics. Another g better stability and longer life. This amp company bought the air lane pans and p could be configured either rriode·con Heath kept the electromcs. Heath HEATH WILLIAMSON nected or pentode connected through the began re-marketing war surplus dec AMPLIFIERYE ARS use of additional primary winding taps Ironics and selling electronic test equip on the OUtpUt transformer. The W-2M ment through a monthly flyer. featured the same tWO chassis layout as I, Heath's first kit was an oscilloscope rhe WI-A bur the outpur transformer was an Altec Utnsin 20-20 Peerless (0-1), they then introduced other types g 5V4G. 16277 and the rectifier was the of electronic leSt equipment including vrYMs, audio osclllam[s, signal gener The chassis were finished in the same gray metallic hanllnenone paint. The W- amrs, tube testers, capacimr checkers 1955. and mher units. The kits were mealll 21'0.1 was discontinued in Over for anyone, with skills from a novice: m 8,000 W-2Ms were sold. an el(peTl, who was interested in elec tronics. Lots of Heathkits were sold to high schools and colleges to be used by budding future electronic engineers. Wl-Al The kits came with a thorough and well-illustrated assembly manual, with Heath decide:d to get serious about el( blue ploded views and large print-like: the:ir audio products during the early schematics, punched and finished chas Fifties Hi-Fi craze. Responding to the sis and all the partS needed to complete Williamson amp popularity, Hcathkit the project. infToduced the WI-AI amplifier kit THEFI RST HEATH AMPLIF IERS ($49.95) in 1952. h was offered as a two-chassis amplifier with the power sup 1947, in Heath began selling ampli ply on one chassis and the amplifier on WA-I'l fier kits under the Heathkit name. the other. The separate power supply was These were primitive-looking units design used to reduce hum, improve He:alhki{ also imroduced the WA-PI with all of the componellls mounted installation flexibility and was connected (519.95), a compact phono/line stage on a single chassis formed from p i ece of by an umbilical cord. It was rated at 15 prcamp. The preamp was powered from sheet metal. He:uh's first amplifiers (A watlS Rt\1S. Tube complement included the power amp (WM-I or 2) through an I. ['."0 A-2, A-3 and A-4) were developed 6SN7 octal dual fTiodes for the dri umbilical cord. The WA-PI was a flat, from circuits found in rhe ver and phase invener, a pair of 807 unobtrusive unit that was finished in gray RadiOIron tetrodes They typically transmitting type connected in hammertone enamel. It employed a D�sjgrur'sHandbook. 12AU7 employed a pair of surplus metal type triode for the push-pull OUtput, and a and a 12AX7 in the circuit. Note 6L6 6VG 5V4G or outputS and a potted out full-wave rectifier. A high quality the extended control shafts which were put transformer (probably a Chicago Peerless 16258 OUtpUt transformer was scored 10 be: CUI at half-inch intervals for unit). Apparently, not very many of used. The power supply utilized a polled custom installations. these were sold and few have survived. choke and a potted power transformer, During the early Fifties, Heath also both manufactured by Chicago. The sold kit tuners including the FM-I and amplifier and power supply chassis were: VACUUM TUB E VAL LEY • GOLDEN ERA EAR L Y HEATHKI T W-4AM The Heathkil W-3M ($49.95), intro du(;cd in larc 1953, was identical (0 the W-2M except for an Acrosound TO-300 high <)ualiry OUtput transformer. This transformer was designed and produced by [ Herb Kcroes and David Hatler of h;rosound Corporation, Philadelphia, Pennsylvania. It featured the famous Ultralinear circuiuy Ihal rcpoflcdly gave tetrode power with triode sound. Having owned several W-2Ms and W-3Ms, [ can stage with Chicago power and output Styling changes including different Icll you that they sound distinctly differ iron. The chassis was finished in baked knobs. The "laSt variant of the A-9 was ent. The Peerless unit on the W-2M has a gray hammertone enamel. The front end the A-9C, introduced in 1957. The A- was all octal. Sold through the early 9C had minor styling updates. Early euphonic and romantic sound, while the 19605 Acrosound unit on the W-3M is brighter, J 9605, there were four variants of the A-7: versions of the A-9C were fin has belief controlled bass and seems more A-7, A-7B, A-7e and A-7D (shown). ished in baked gold enamel. detailed. For a while, in the early 1950s, Another inte rated amplifier, the the W-2M and W-3M were uffered in the g A-8, was made rom 1952 [hru 1954. Ir same catalogs. The W-3M featured the f featured an all octal front end with 6L6 gray hamrnertone-finished chassis in early OUtputs. The chassis was finished in versions, and was latcr sold with a gold baked gray hammertone enamel. The metallic finish from J 959 to 1962. The audio transformer was a non-potted W-3M was a very popular amplifier for its Peerless unit. The A-S was the forerun day. Over 12,000 of them were sold. ner for the A-9 series. HI FI ON A BUDGET In the early Fifties, the Hi-Fi cra�e was gaining momentum. Several com panies began to offer high-quality amps. A-9 When you consider that the average weekly wage was about $50 to $60 a Trying to penetrate the beginno::r audio week, a $200.00 amplifier COSt a enthusiast market, Heath lIltroduced the month's salary. To get more music W-4M ($39.95) in 1954. The cube corn" lovers into Hi-Fi, Heathkit introduced plement and circuitry were similar to the the A-7, A-S and A-9 integrated ampli W-3M, except that the entire amplifier fiers. None of these amplifiers were of was on one chassis. In addition, the Out the Williamson design, but were similar A-8 RadiOIron put transformer was a high-quality to circuits found in the Transformer purred unit instead Designers Handbook. Chicago Introduced in late 1953, tho:: A-9A of a premium Acrosound or Peerless. (535.50) was also an integrated amp lifi These changes saved the buyer about m 20 er fea ring wart 6LGG push-pull $10.00 (aboUl a day's pay In 1954). output stage. Preamp and front-end mbes were miniature 9 pin 12AX7 and The amplifier was rated at 20 watts 12AU7. The chassis was finishcd in RMS, but actually pur out abour 17 baked gray hammenone enamel. The watts RM:s. The first versions of the power transformer was a smaller W-4M were finished in gray hammer Chicago potted unit and the OUCput was tone metallic paint. Another variant a small non-potted Pecrlcss unit similar was the W-4AM (1955-59), which was to the A-S amp. First introduced in the first to feature stenci!ed lettering on 1954, the A·9 featured a larger potted the chassis. The W-4A.t\1, featuring A-7D Chicago power transformer and a potted either a gold or gray enamel chassis, was 1959. Chicago audio transformer. In 1955, the introduced in late The W-4B, ($15.50, 1952) The A-7 employed A-9B was introduced; it feamred minor featuring a slide type power switch 011 push-pull 6V6s (or 6 wartS in the OUtpUt VACUUM TUB E VALLEY • GOL DEN ERA EAR L Y HEATH KI T amp. It featured Mullard ECC82 (l2AU7) and ECCS3 (l2AX7) dual uiodes and was finished in gold enam e!. The XO-I tube electronic crossover was also introduced in 1955. It was finished in gold enamel and featured a black tube cage. The compact gold fin ished FM-3 mono FM tuner and BC lA AM tuncr were." introduad in 1956. W-5M E[((tron;c Cross-ovrr the from panel was introduced in 1961. poned choke. The power rating of the XO-I The last version of the W-4 amp was the W-5M was 25 waits RMS, but some Without question, the rarcst and most AA-71, sold in the early 1960's. It was sets test at more than 30 wans RMS. exotic of all Heathkit amplifiers is the W_ similar w the W-.tiB, except for the black Through 19S7, W-SMs featured the 6M(SI09.9S), introduced in 19S7. enamel finish. We estimate that over larger Peerless 16458 OUtp", trans Generating o,'er 70 wam RMS and 140 2S.000 kit and facwry assembled W-4s former. From 1957 through 1963, the peak music wattS, it was Heathkit's most were produced. newer design and smaller 16309 powerful mono tube amplifier. It was a output transformer was MID-F IFTIES HEATHKlTS Peerless large unit with a gold enamel chassis and employed. Though more common, the a small. black metal tube cage, mOll!Hed Perhaps the amplifier that most of 16309 is no slouch. It has exceptional directly over the tubes. Bias, variable associate with early Heathkit is the characteristics and performance. Some damping, powe'r switch and meter IYcre liSW-5M ($59.95). Introduccd in 1955, Heath expertS claim that the 16309 located on the front panel. The output Peerless has more extended highs. 6SS0s. it was acce'pted almost immediately by tubes we're Ihe' famous Tu ng-Sol the audiophilcs of the time. It was Tung-Sol introduced thesc tubes in 19;; truly a "hIgh-end" amplifier for a bud specifially for audio use. Prope'rly driven get price tag. The amplifier was and and biased, with a 600n plate vohage, a still is a beautiful audio artifact. pair of 6SS0'5 could produce 100 wans in Class AB 1. They featured gold Finished in bright gold merallic lacquer RMS and topped offw ith a complete cage plated grid wire for bias stability and long finished in black wrinkle', it featured life. the famous Williamson design, this The W-6M lYas (he first HC VACUUM TUBE VALLEY • GOLDEN ERA EAR L Y HEAT HKI T menc, overall circuit inspection, and repair. Some collecwrs will not pay wp dollar for reswred amplifiers, insisting chat all components must be original. It is a good idea w save all original resis tors and capacitors in a plastic bag to be insralled larer if you sell the unit to a collector. When replacing capacirors and resisrors, be accurate and thorough. Use exact values and equal or greater voltage ratings for capacitor replace ment. Check all soldering joints and re-solder as needed. Remember, many of these were kits assembled by neo phytes who were just learning ro solder! Remember to enjoy your work, take your time and do a quality job! CONCLU SI ON This article covered the early tube mono Hi-Fi ),earsof Hearh Company. The Heath - Daystrom and Hearh - W-6M Schlumberger tube Hi-Fi era, 1957-64, will be covered in a fumre issue of VTV. Production figures listed for Heath the W-6M could not bias many perfectly AA-91, available in the early I 960s. It equipment are estimates. We welcome good 65505. Perhaps as a result of this, featured a black enamel chassis and a your comments and/or substantiated the W-GA, replacing the W-GM and pro gold painted cage. corrections w this article. duced from 1960 to 1962, had addional ENJOYING REST ORING bias comrols and input level controls on AND YOUR HEAT H AMPLIFIER Spuial thanks to Bill Short of the front panel. Edmonds, Washington and Km tViLwfIof Properly restored Heath Williamson San }ou, Californiafor their assistance Over 90% of amplifiers sold during with this article. the mid-Fifties produced 30 wattS RMS type amplifiers can sound great with the right speakers. If you plan to use an or less. It is obvious that the W-GM was I early Heathkir amplifier in your s stem, Heath Nosttligia, 1992, Terry desi ned for rhe audiophile who needed y - � carefully plan your project and take [he Perdue, 4320 I 96th S.W, Suite B rhe ultimate" amplifier. Some experts Ill, Lynwood, WA 98036-6754 (This estimate that less than 2000 W-6M time to do a good ·ob. Vinta$c tube Hi Fi restOration invo ves: rcmovlllg dust is an excellent book on the history of amps were ever sold. That would make I Heath Company.) tho.> W-6M and W-6A the mOSt collec and grime, detailing, replacement of coupl ng, table of the Heath tube amplifiers. i bypass and fifter capacitOrs (borh paper and electrolytic), tube sock o.>tcleaning, tube teSting, tube replace- In 1957, the Heath Company was sold w Daystrom, which expanded the production facilities and increased capacity. Later that same year, the UA I, a small mono 12 watt power amp using push-pull EL -84s in the OUtpUt stage was introduced for $22.95. Numerically, the last of the Heathkit Williamson amplifiers was [he W-7M ($54.95). Introduced in 1958, it was the first "a dollar-a-wau" high-powered amplifier. It was nOt really a Williamson design, but resembled a Mark 1I Dynaco. The from-end circuit consisted of a pentode driving a split load inverter. It was rated at 55 watts RMS from a pair of Mullard EL-34s. The driver/phase-inverter stage was a single 6AN8. Rectification was handled - by silicon diodes. The chassis was baked gold and clear-coated enamel. The W- 7M was equipped with a 10tLvered black W-7M wrinkle cage covering the entire amp. A later variam of the W-7M was the VACU UM TU BE VALLEY TUB E REVIEW EL34/6 CA7 THE EL34REPORT, HislOry and Comparisons by Eric;: Harbour I. History The tube industry has �een plenty of ironic changes. So many twists and [urns go by, leading us 10 the 21st cen tury without a dear idea of why a given tube is Slil1 popular. For example: what if Leo Fender had used 2A3s in his gui tar amplifiers instead of GLGs and GV6s? Todays guitarists would likely have developed a very different idea of what a good guitar sound is. The same is often true for the tube Hi-Fi community, whether they recog nize it or 1101. Onc of rhe mOSI popular power tubes of all was originally intend ed as a cheap way of getting 40 watts Mu/lordEL34s -/ to r: Typ� J, 1jp� 2, 1jpe3 .and lAu rype3 with high sensitivity. The purpose was 10 allow amplifier designers to mak� a use in th",ir Mark 11 and its 10w�cost from other tubes in guitar use� Because driver/phase spliner with a minimum st",reo version, the Sterro-70. At l(';3St they were low in cost and had a less component count. Low distortion was half a million Stereo�70s w�re sold from massive plat� struccure than 6550s and incidental, as this tube was (0 be used in 1958 to 1977. The EL34 is also found similar types. Since the signal voltages a push�pull pair with negative feedback, in the Marant"t 5, 8A, 8B and 9; the H. in a tube amp can get very high at and other applications (such as radio H. SCOrt 240, 250, 280 and 290; the times, the tube's piezoelectric and transmitters) were nOt really even Eico HF 50, HF 60, HF87, HF 89; tht: mechanical behavior can influence the addressed, Alrhough bealll�power Heath W�7A; the Acrosound UL�II, sound. Overall, mOSI EL34s have a soft tetrodes had taken over the market in UL� 120; the Fisher SA�300 and X� er distortion tone than 6L6s or 65505 (he 1940s, lhis n�w cube was a true 1000; 2nd many, man}' others. These are: because of the construction differences pemode, all archaic design by the stan some of the best tube Hi-Fi amplifiers and the pentode design. dards of the day. This may h2ve b�n ever made, all usin �a cheap way of g The so�called 'STRs' and K'177 arc done in order to circumvent RCA's geuing 40 wans.6 So it wasn't such a patems on beam cubes. bad tube after all. And in fact, many actual� beam types and tend toward audiophiles prefer it over the 6550 and more hard6 quality. This is usually not Strange as all this must have se:erne:d, other types. easy to hear at low volumes, but is quite MuIJard took JUSt {his big leap when apparent when the amp is pushed into they introduced the EL34 in late 1953. The EL34's popularity was sealed clipping distortion, especially in a guitar [n spite of the low-cost intent, the early when Jim Marshal! selected it for his amp. So personal preference can be a EL34 was an excellent tube. The JTM 45 guitar amp in 1965. He went majOr factor. Mullard early version (recognizable by with it because it was cheaper and easier the metal ring around its base) could to get in England than the 5881 he had 2. Versions defeat any 6L6 easily, and was almon a used previously. The JTM 45 became a No power tube can compare with match for the 6550. It gave easy drive standard for the British blues-rock the 6L6 for sheer number of variations, and considerable peak power, from a tall sound. The EL34 also found its way bUl the EL34 was quite popular, and and thin glass envelope that saved space inro Hiwatl, Orange, Traynor and thus many EL34s and EL34.likes have 011 chassis. Mullard's book Circuits For Laney amps, all made in Britain. been marketed over the years. This is AlldioAmpiifin"J, first published in 1959 Because the EL34 has a much more: pro· still trU�, with five (soon 10 be six) ver, and recently reprinted by Audio nounced distortion characteristic than sions currently being manufactured in the 6550 or other similar ower tubes, Amateur Publications, featured the 1995. BUI the perfectionists srill look to EL34 in the largest power�output its sound is distinctive anJ is a major NOS versions for the standards. design. All the other amps in tha t book influence on the hea\'Y�rock sound used the much small",! EL84 or ECL82, palette. Marshalls are often run full�till, Mullard sold three major editions, all which has caused reliability problems. quite different but all of very good qual� Among the first amps to use it were In fact, the American importer of ity. The first we have already men� lhe Marantz 2 (I955), Dynaco Mark 11, Marshalls was putting more�rugged tloned: the metal�base version, called and the Pye Mown, a single�el\ded 9� 65505 in the amps during the late 1970� the "Type I." The base ring is actually a wall British unit from 1956. The easy and early 80s. But when new distribu srampillS of nickel�plated steel. The drive requirements allowed a 30-40 wall tion was set up in 1986, Marshall was tube inSide it is one of the best; original amp to be built using only 3 tubes: the adamant that the amps be equipped Mullard data sheets give maximum volt twO EL34s, and a triode-pentode as the with EL34s exclusively. age ratings of 650 for the plate, 500 for voltage amp and phase spliner. This the screen. Dissipation has always been made the EL34 a must for Dynaco to Why do EL34s sound so different listed at 25 watts, but could usually be VAC UUM TUBE VA LLEY • TU B E REVIEW EL34/6CA7 exceeded (and often was in certain gui rar amps). This may seem unlikely, but well-used -lype [s often have heat-suess cracks in the meraJ ring yet call still teSI like new. TheType I was believed to have been manufactured by Dmeh Phillips. TheTy pe I [ had a large base of dark-brown bakelirc, bur was quite sim ilar in orheT respcccs to theType L This version appeared around 1959. It is often seen relabelcd 6CA7/EL34, with ReA, GE or Sylvania logos. (The American JEDEC designation 6CAl apparently was bestowed arOllnd 1960.) The Type 11 was also rhe original tubc seen in 60s Dynaco amps, with the Dynaco brand. All the Mullards call be recognized by a pair of 4-digit produc tion codes imprilHed on rhe glass with a permanent paint.The Type I and 11 had crimped plates with ("wo rectangu lar holes on elther side, the classic pro file. Tht:Type HI appt:ared around 1968-69. Its base was black and smaller than rheType I or IJ' base, with a simi having a mend ring which is even more The Siemens appeared in the lare lar suucrure inside.There were dHee prone to cracking.The plate was weld 50s. lr was much copied and rebrand variations of the 'lYre 1II: first with ed and had one re(;langular hole. This cd, being especially Inexpensive due to It twO getter "haloes,' then with one, and version was sold until the 19605, when some production in East Germany. finally (in the 1980s) with one halo and the base became plain bakdite. There has distinctive "Haple» protrusions a Spot-welded plate. Expens say that were three versions with the plain base: holding its plate halves tOgether.This Mullard's quality started to slip in the one with one rectangular plate hole, was the first type to claim a phue \'olt 1980s, and the welded plate EL34s, the another with [Wo round plate holes, age capability of 800 volts. It was often least consistent of all, had screen-dissi and one with a small V-shap ed tab sold by other companies as a 6CA71 pation problems and ended up being welded to each side of the plate. Real EL34, and the data sheets in old Tung the last true Mullards.The plallt was Teles were apparently made rill the Sol, RCA and GE data books reflect the torn down in 1982. Since Philips 1970s, and EL34s brandedTclefunken BOO-volt raring. The Siemens plam was after that were probably made by shut down after the fall of (he Berlin owned Mullard, some Philips and Norelco EL34s were acrually made by Siemens orTu ngsram. There have also Wall in 1991.Tu ngsram, the huge Mullard (see Amperex below). been beam- ower versions with the Hungarian lamp maker, made a Yery Telefunken brand; their origin is close imitation of the Siemens' srarting Probably the first competitor was unknown and they wefe seen in the in the 19705. Tooling must have been theTelefunkt:n, sometimes branded American market in the 19705. bought from Siemens, as it is almost AEG. It looked similar to the Mullard, impossible to tell them apart. And the Tungsrams wefe often rebranded and marked as having been made in Germany. Things set really complicated with Amperexl Phtlips. I personally have seen Mullard (not surpnsing since Mullard was owned by Philips), Siemens, Tungsram and even Matsushita EL34s carrying the Amperex "Bugle Boy" logo. Rebrands became epidemic in the 19B05, and the Siemens,T ungsram and Tesla versions still pop up with all kinds of brands on them. Some have even been spotted with "Made in England" imprints. Supposedly, Dutch Philips made its own EL34s in the 1950s which were sold as Bugle Boys-they arc very scarce in the United States tOday and I have never seen onc. Philips bought / to r; Dutch AII/pertxBugle Boy, GE labtledMul/,m/' Amperexlabel,d Timgsralll, Llftr ](fefilllkw VACUUM TVBE VALLEY - TUBE REVIEW EL34 /6 CA7 Amperex, an American maker of indus trial tubes, in 1955 and began marketing its own production in the USA under rhe Amperex name. Although some receiving cubes were made :H the Amperex plant in Brooklyn, the manu faclUre ofEL34s is unconfirmed. [n 1959, the Marconi-Osram Valve Co. or MOY (a division of British General Elecuic. GEC·AEI) produced its own version of the EL34. The KT77 isn't even a pemode; it is a beam ( trode like the 6L6. It was made this way ro circumvent a Mullard patent on the EL34 design. Although the K"177 looks like a skinny EL34 of European make, il is nOt a true EL34. [tS tiny brown bake lite base and [cd "Gcnalex Made In U.K." decals are distinctive. It is the proof rhat a really rough tube can be: made in a small bottle. The original KT77 data sheet liSts plate diSSIpation Tesla was a large manufacturer of equipment was bought by fo rmer of 32 wans, maximum late voltage of lamps and tubes in Czechoslovakia. One frequent question I §et is, Mwhat caused the ST.R ro Ix made? and 1 have yet to find the exact reason. What I do know is that Sylvania had been rc:label ing Mullards in the 1960s with the des ignation 6CA7/EL34, and sellin� them in America. Then, in 1973, the 5TH." (special test requirement) 6CA7 appeared. Rumor has it that Mesa Boogie approached Sylvania and asked them to make a rugged version of the EL34 or KT77 to be used in Boogie gui tar amps. Because Fender's STR version of the 6L6GC appeared Ixfore it, and looks quite similar, it is suspected [hat both these tubes are based on the same structure, which is JUSt the standard S)'lvania 6L6GC of the late 1960s. VACUUM TUBE VALLEY TUB E R E Y E W : EL34/6CA7 Ironically, the term "STR" started envelope, makes a solid foundation for a out as Sylvania internal technical jargon, good power tube. It is not shown in the but has become generic for the "fat" test charts here, because the samples GCA7, regardless of manufacturer. There were pre-productionLater versions have is now the $ovcck 6CA?, which looks flash getters .. like [he Sylvania and is colloquially caUed rhe"Sovtek STR." The Sovtek 3. The Tests and Results New Sensor people have two versions Since 1 wamed 10 find Out [or myself for sale now. One is a skinny pentode ill which versions of given tubes were the the European style, called an EL34G (to best, I built a singre-ended amplifier settle all the arguments, the "G" doesn't especially for test-bench use. The amp seem to have any special meaning). The has twO power supplies: 500 volts D C other is much like the old Sylvania for plate power, and 300 volts DC for 6CA7-STR. It's made with different platc or screen. A variable bias is applied materials and so is easy to spor. I will to the control grid \'ia a potcntiometer say no more about $ovteks because New and a 47k resistor. The output load is a Sensor refuses 10 discuss their products One Electron UBT-I, used with an 8- The GCA7 STR is a beam terrod!;:, or reveal production details. ohm load connected 10 the 4-ohm tap. but apparently with the screen grid not Shuguang has been making EL34s This gives an apparent 3200-ohm pri aligned with the conlfol grid. Th e result for at least 10 years. Their version is nOI mary lO:ld to the cube. Such a load may not is nOt quite a pentode and not quite a very good, but had seized the market for be exactly wh:lt manufacturers' data ood beam-power ty pe. In spite of thIS, the some time. Early olles were never built sheets recommend, but it makes a g tube is one of th e most rugged versions compromise for a wide range of tubes, straight, and frequently developed of [he EL34 ever. It ended up being shorts. The current olles have brown from 2A3s to EL84s. So long as [Ubes of designed into many guitar amps in the bases and seem ro be a little more con a similar type or family are compared, the results fo rm ! 970s and 19805, to the sorrow of their sistent. Because other rube fa ctories are a useful database. The currem owners, as modcrn EL34s may defunct, and because this tube is so driver is a 6EA7 with the high-mu tri ode as the gain stage, and rhe low-mu not take the punishment these amps can inexpensive (the twO facts may be ilHcr triode directly coupled 10 it and serving inflict.Sylvania made three versions of related), this item is commonly sold by as a cathode fo llower with a 12k-ohm the GCA7 STR; the early one having a many disuiburors. As with other load. The output is coupled to the round lOp and top gener, :lnd twO later Chinese cubes, the cathodes are not power cube with a 2-uF Spr:lgue versions having a more squared-off top , well-processed and are made with one with an additional side geuer. RCA impure materials, so the lifetime will be polypropylene capacitor. When driving about 10-20 volts RMS into a tube TOok these lObes and sold them, as did shorter than with NOS types. Mes:I and other guitar-amp manufactur under test, this driver has distortion of ers. GE started making their own ver Svedana has a skinny EL34 that, as less than 0.02%. Distortion was always sion in 1975. 80th these tough tubes of this writing, is almost ready for imro measured at one watt into the 8-ohm are now out of production, and musi duction. 1 received some early samples, load, at 1000 Hz, using my Vu -Data cians are regretting it. Both tubes are and they appear to have great promise. 1018 analyzer. rated 800 volts plate, 425 volts screen, Early samples did not use flash getters, Because third harmonic distortion at but still 25 wattS dissipation which, in instead anaching tWO pill etters to the g one watt is barely readable with all of this case, was quite conservative. plate. That, combined with a hard glass these tubes, only second harmonic is shown. There is one weakncss which the EL34 is prey 10, and that is screen over heating. Because this tube is a "true» pemode, the screen's wires can be direct l y in the electron streams passing through the comro! grid. If the tube is rriode connected, the screen may devel op hot SpOts. If the screen gets toO hot, the control grid next to it will also over heat and emit electrons, thus causing . runaway plate current and destruction. I This is dependent on the plate voltage and currem. Most amplifiers rUIl them at 500 volts on the plate at 50 mil liamps, which is 25 watts, the rated limit. A given tube that has a small defect (\vhich will not appe:lron a tube tester) may go into thermal runaway once plugged into :In amp. The Mullard data sheet recommends a resistor of a[ least 1000 ohms in series with me screen ill order to prevent this. l to r: TUlIgj ram EL34, SOVTEK EL34G, SOVTEK 6C4.7alld Svetlalltl EL34 Most EL34 guitar amps ha,"C these VACUUM TU B E VA LLEY • TUB E RE VIEW : EL34/ 6CA7 resistors, but the users fr �u�ntly run C - pay the price for NOS tubes. Be Ta ble 1: avcrage distortion at I watt, them deep into dipping for long periods, warned, these prices can only increase. EL34 samples. Arranged in order of which can be risky. Most Hi-Fi amps, There are dealers for NOS, but the sup increasing distortion. Second harmonic such as the Dyna Mark fl and Stert'O-70, plies can be described as extremely unre only is shown. Tu bes were new in origi are in ulualinear connection, which runs l iable. Often, dealers obtain NOS tubes nal boxes except as indicated. the screen at slightly more than the p!at� from people who sell their personal voltag� and has no screen resistor. The stashes; often they appear at estate sales Type DhtQrtion , Samplc) screen tap on the transformer doesn't or in military surplus auCtions. The peo KTn MO 0503% 3 (used) really limit screen current, so a tuhe plc who make a hving this way havc to Tdefunk�n lype J 0.5!; 2 (used) might idle OK with no si�nal and o work very hard at it. Old KT77s, Td erunkcn lun 0528 6 (used) g arc berserk whcn the volume IS cra nked up. Mullards and le lefunkens especially Te sla EU4 0550 1 I currclll The current importcd tubes have s�rious scarce now. have seen Type I Mullards Mu1l3rd [)'� I 05)3 3 (2 uied) problems with this. sell for I SO each. S Sylv 6CA7-STR 0.613 16 (12 u$C VACUUM TUBE VALLEY • THE A U 0 o T EST BEN C H Sowk EL34G . . ...\4.7 preference - others may have different TUllgsram ....14.6 The Audio Test Bench preferences. Readers are welcome to sub KT77 MOV ...... 14.5 mit their Oll"n ideas; interesting or ,on stru,tive <:Olltributions will be summari7.0cd Tddunken type [ ...... 14.) by in future issues. S),lvania 6CA7-STR ..14.4 John Atwood Telefunken later ...1 4.3 The Test Bench Tesla E34L 80s ...... 14.1 A [est bench needs 10 meet the follow ing uiteria. It muse 4. Outro Th e Te st Bench and Tools Be comfonablc [0 "'(lrk al. Thi, includes It is uitimatdy up to du, ll$l;:r to good ig g and a good chair d<:cide on which tube is best. Personal This is the firSt of a series of articles l hrin . desuibing in depth the tools and equip tastes vary, especially among guitarists 2. Prov de enough bench space to work on ment needed 1:0 design, build, and test i (some arc very conservative perfection your cquipment wilb enough room for audio equipment, with a special emphasis iSts, others are always open to new pans. notebooks, etc. sounds). Hi-Ft is also sub jective, but to a on vacuum tube technology. This is nOt a lesser extent than musical amplification; retrospective series; it sometimes calls 3. Provide enough dectriC".a! oullels to power to whelher the some audiophiles admit it upon rhe technology of the 19905 all the (cs[ equipment and unit unda tC.\[ or not. Since most EL34 hi-fi. amps use implement a produ<:live working environ in a safe manner. negative feedback, they afC less sensitive ment. However, vimage equipment that is 4. Hold tools �nd (r�q�lend)' used p�fIS close ;IS still usable will also be described. While ro the quality of the tubes used, ('H as 10 your work position such as d wers or the focus is on audio work, much of (he in ra distOnion soes. But a well-made rube, bins. with low dlsrorcion and srability, is an tools and equipment is applicable to radio asset which is (unfortunately) gCHing and industrial electronics as well. 5. Provide �nough space for le,I equipment harder to find in the 1990s. This is without ompromising on benchtop space. Anyone who builds or fixes electronic c especially uue of the EL34, a classic but equipment needs a place to open up their In the cle'Honi,s industry, the Stall nOt necessarily the finest power tube equipment, make small repairs, and run dard work benches are 36 in�hes tall, ever. electrical tcsts. This ,an be as simple and often with add-on drawers, an overhead Many thallks to Haden BOllrdman temporary as setting lip on Ihe kit,hen shelf, and built-in power strips. New, thest ilfld Aspen Pittmall for �ble to as complex as a dedicated indus ben,hes can cost hundreds of dollars, but their help with JUSt biuoricaf information. Aho thanks to trial test bench. If you do more than can often be found 3C industrial surplus John and Ch ar/iefor loalling me tbeir occasional COnstru,tion and repair work, stores for under SIOO. It is also possible [0 NOS tubes for testing. then a dedicated work spa,e is very help build [hem from wood or from kits avail fuL This ,an be a corner of the garage or able from hardware stores. basemem, pan of an unused room, or a bench at your workplace. Stocked with the I've found these high ben,hes some righ t tools and equipment, a dedicared what inconvenient, requiring spe<:ial high workspace will fa ciliTare [he process, free �lab" chairs. I prefer to work at a regulat ing up your mind to concentrate on the height desk; this allows the use of com problem at hand. monly available desk chairs and acces sories. Desks also have convenient drawers This series draws on my direct experi and pull-oUl surfaces. It is important to ence from working as all audio tc<:hniciall use a deep desk (34·' or more), otherwise HI college, a computer hardware engineer your test equipment will not leave much in industry, and as an audio designer for area to work, especially if you use older my own company. Sometimes {he ,hoi,e tube-type teSt equipment. My fav orite test of tools or equipmem is based on personal bench is an old wooden executj"e desk Eric tests 300& ill the Willter '95 VTV VACU UM TUB E VALLEY "!!"- THE A U 0 o T EST BEN C H (the kind that has (Wo sections with a large wooden lOp and center drawer co nnecting the two). It is beat-up enough that I don't care about scratching the top, and its capacious drawers hold plenty of pans, tools and documentation. It is helpful to have a shelf over Ihe desk or workbench 10 hold test equip ment. This can be purchased or made from plywood. Be careful, thou h. because many shelf units made !or regul:.tr office use have closed backs, making it dif I1cull to handle deep equiplllem and wiri g They also may not be strong enoughn . to hold heavy equipmenl. In earthquake-proru: areas, il would be pru dent 10 anchor the shelf and fasten the equipment 10 the shelf, to avoid injury or damage in an eanhquake. If the desk is metal, the frame should be connected 10 the protective ground (the green wire in American wiring), and an insulating mat be placed on the surface. The mat can be audio and computer equipment. My om mended, especially for the sizes used of the black conductive typt" (anti-ESD Stanley 64·131 I.point Pozidriv screw for controls and switches (1/2" and mal) if the resisnnce of the mat is high driver has been very helpful in loosening 9/16"). A\'oid the cheap combination set�; (over 1 rnegohm). These precautions are tight screws made of soft metal thal would their metal is usually soft, and will deform not usually needed for low-voltage solid have been ruined by regular Phillips after only a liule use. For nuts [hat can't State work, but with the high voltages screwdri ers. Xcelite is the dominant be handled by the nUldrivers, an uS(d with vacuum tubes, it is important to brand inv the American electronics indus adjusrable wrench (sometimes called a prevent unanticipated stray paths that try, but premium quality screwdrivers Crescent wrench) is useful. A S(t of could cause a severe shock. from other manufacturers, such as Paladin midget wrenches (from 7/32" to 7116") is (Weralit), Prow, Snap-On, Stanley, handy for holding nUlS in bard-to-reach Hand To ols Ve rmont American, Crescent, and others places. A very useful tool that anyone who The hean of anyone') IQt bench is are jun as good or bener. Smmgely, has built a Heathkit will remember is a their collection of hand tools. These Xcelite does not make a POlidriv type with nUt starter. This is a plastic IUbe shaped 10 mechanical aids 10 assembly and disassem a regular plastic handle. hold I14� and 3116" nUts and gel them bly arc the mOSt inrimate link between starled on the tbreaded screw shaft. and man and hardware. Of all the lools and Alien Other Hex-Socket Type Wrenches Pliers equipment described in this series, good quality and appropriate hand tools will Most setscrews in knob and shaft Ilard The single most impoTlilnt hand tool provide the best productivity and satisfac ware as well as some regular screws use the for electronics work is a good long-nose tion. This is why master mechanics have Alien hex socket head. Initially, a combi pliers These will bear the brunt of bend (heir own tool box, and jealously protect nation S(t of hex wrenclles ranging from ing wires,. exploring circuitS, desoldering, (heir 10015. .050" to 3/16� can be used. I find that the holding partS, and many other taSks. Most .050", 1116", 5/64", and 3/32� sizes are electronic technici s have their own re Note: the si·l.C. of the tools described p used the mOSt, and so have plastic-han ferred brand. Minean is the D301-5C 5 here an.' fwm the American point of view, dled versions of these. If you do any repair long-nose pliers by Klein To ols. Other with sizes specified in inches. In other or disassembly of military equipment, you good brands include Diamond, XceJite, coumries, metric sizes would be appropri will n�d a set of Bristol spline screw and rem Look for long no ( pliers with ate although cerlain common sizes, such E drivers. These are hard to find, but Xcelite ends that dose. tightly and- haveS little play. as ,1I4� hcx-hea VACUUM TUBE VALLEY .. TUB E INDUSTRY NEW S nose pliers are good wire cutters. They women used on the electronic produclion sometimes helpful for holding wires or should be fl ush on OIlC side ro assist in lines of the 1940s and ! 950s, componcms in place while soldering. trimming circuit board leads. The culling edge should meet evenly and Ihe: joint The electronically controlled soldiering Where To Get To ols should have lilll<: play. The: good manufac irons allow adjustable tip temlJ'Crature and If you are 111(;:]..." enough [0 live in an turers of electronic wire cuners are the: doser temperature control. The fancier area with Iou of electronic industry, retail same: as for long-nose pliers. My (,l\'Qriu: unirs ha\'e temperature read-outs, and SlOres and industrial distributors will carry [}'pe is the K1cin D244-5C. A large elcctri some are e\'en microprocessor-comrolled. the tools described above. �hil order out· cian's wire CUller is good for fal wires or These units are primarily for produclion fits that specialize in electronic tools sted wires that will damage the smaller pli work on high-density PC boards. include: ie chni-Tool (610 941-2400, FAX ers. There arc lIIany good wire strippers, I us,," the Weller wTCrT magnetically 610 828-5623) and Jensen Tools (800 some of them fairly complex, to prevent controlled iron, with three lips: a 1116" 426- 1194, FAX 800 366·9662). nicking the: wire and to ac,ommoJate dif 600°F rip for fine board work, a 3/32w ferent wire sizes. I prefer to use ,he simple rc Note: am not an employee of, nor 700�F tip fo r general purpose work, and a I type. such as Ihe Xcclitc #100, and modu recei\'ing an compensation from any of 3/16� 800°F tip for heavy-duty work. y laIC Ihe depth of the: cut by fe el. When CUl the companies mentioned here. where the high temperature is nOt a prob ting very fine wire, such as Wire Wrap wire lem. (30 gauge), J use Clauss No Nik mippers. Th, Audio "ksf Bmch f{)picfor lI('xt iiS/l(: SlJidu DC Ideun Miscellaneous To ols Soldtr i� becoming an area of high-end designer products, but the metallurgy for Other useful wols iuclude: twcezcrs, a high-quality, long.lifetime solder joims Tube Industry News paint brush for cleaning. fo rceps m hold has been understood for many years. The '" wires, co:u; cable cuners, co:u; connecmr traditional 60/40 solder, also called Sn60 by crimpers, a crimping mol, small files, den (60% tin, 40% lead) is actually quite Eric Barbour Ial mirror, lead-forming gauge, Xacm good. Eutectic solder (63% rin, 37% lead, knife, and fuse-puller. Not covered in this called S1I63) has no "pasty» state, and so article are the many tools used in chassis solidifies mOSt cleanly. Silwr bearing sol SURVEY RESULTS and other mechanical construcrion. der (62% tin, 36% lead, 2% silver, called Sn62) is needed 10 solder 10 ceram ic ler Tho;: results of the tube indu�[ry �Uf\'ey SolJering To ols minals, such as those fo und in Te kuonix are in. \'(Ie sent questionnaires to all of the Soldering has been the basis of m05t equipment. I use Sn63 for mOSI soldering, major distributors and mail-order dealers, electrical connections from the turn of the but am preparing lO try some other types with generalized queslions about the num century to the latest surface-mount lech for their sonic qualities. bers of preamp and power tubes (nOt nologies. The intricacies of soldering and including industrial and uansmilling Flux is an essential pan of solderin . soldering lechniques will not be covered g typ�s) they had sold in 1994. Th� aVl!fage Nearly aJJ electronic wire-type solders have here; JUSt the lools commonly used for dealer sold 79,000 tubes laSI year, of both flux cores = osin, MildI)' solder at tile work bench will be described. Rt\{A (RMA R types. The \Oral is es�imated at about $12 Acrivaled), which is good for nearly all million in power tubes, S8 million in pre Sokkring lroll hand-soldered eleclfonic needs. Be careful amp fypes, fo r:m industry tOt;!;] of about I nOI lO use so-called acid-core solders There are thfee types of soldering million tubes. Note Ihat these are approxi nt unless you very carefully remove all flux irons: unco rolled, magnetically con mate fi gures, and do n01 include some residue. Major bronds of solder include trolled, and electronically controlled. The OEM sales. Most of this is direct sales to Kester, Alpha, and Ersin . uncontrolled type is rhe cheapest, and consumers plus smaller OEM business. suitable for casual uses and non-critical The origin of these tubes is somClhing like point-to-point wiring. It is not suited to D(iIJ/d,rillg ToolJ this: PC board wiring, since it has a high lip Desoldering is an imponan[ pan of temperature whieh can damage the PC repairing or disassembling electronic NOS (Aml!ric-..n and Europo;:an). 23% l equipment. For th u -hole board board and its components. A CO urolled ro gh rc Russian ...... 30% temperature soldering iron has a thermo dc:soldering, the spring-loaded solder suck Chinese .., ...... 30% Stat-type sensor that keeps the tip within a er or solder-wick desoldering braid is ccrtatn temperature range. good. For taking the solder OUl of a point Tesla...... ,. , ..... 16% to-poilll wired con nections, I find that the others ...... <1% The cheapeS! controlled-temperature rubber bulb solder sucker has Ihe best (error: approx �oldering iroll is the magnetically-con SO 8%) control. It gets clogged frequently, I use trolled s type that uses the Curie tempera Ihe lead of an old 2-wau resistor to dear There is slill significant business for a as the r. ture of magnetic alloy sensing the sucke NOS products toda),. In faCl, the largest mechanism. The Weller W60P and distributor is doing lar!!:e quantities of of T()()is WTClyr are typical this type. Tips an� Holdillg business juSt by selling ItS old stock off. available in 600°F, 700°F, and 800°F rat When soldering small pans or �ub Some mail-order dealers are handling i gs . The n controlled temperature make assemblies, you somctimes wish you had NOS as a speciality, and the demand these irons safe fo r PC boards, and the three hands. There are vatious holding seems to be increasing, even as the sup thermostatic comrol gives the sense of a tools available, including the well-know plies dwindle. Good news for )'ou hoard much larger heat capacity for a given sizc s v , l'ana-Vise. I u e a hea y-du[)I but effective ers. Most signifi cantly, the demand for of iron, making point-to-point soldering alternative: a drill press vise. It doesn't audio tubes in general increased IllSt year. is no nc:c:d for the easier. There giant skitter around like some lighter-weight Only one dealer reponed thal sales were uAmerican Beauty" soldering irons that holders. Alligator dips or forceps are VACUUM TUB E VALLEY • CATHODE B A S f\a(, and none reponed chac sales had VA IC VV52B declined. [n the words of one dealer, -'- "things are exploding." This is especially This giant power triode is new IQ the world market. It is intended to be a seri Cathode Bias amusing when you compare it to the V.s. ous competitor to the 211 and 845. blll Department of Commerce's own figures by uses a standard 2A3-rypc:c sockel and has on receiving mbes. Their latest figures an oxidcc-coaled filamenT. -1-- John Atwood were for 1989-1990, and they were blunl; �inves{mclH opportunities are poor.· They Filalllcm - G.O to GAV ,\C1DC, at 2.0 IU had about $26 million in sales for only 2A amp� cha! period, and issued proclamations of Help Conserve a Finite Resource doom for the American manufacturers (all Platc \'oltag� - 650V ma;(. Despite claims source of tube� of which had already shut down their fac that the m;n;. tories, except for MPD and Richardson). Cathode current - 200 mA are �drying up�, Ihere are slill warehouses Try calling information in the 814 area full of tubes, and numerous pc:crsonal col Plate di ��ipalion - 85 "","I(� mu. code:. Ask for the number of Philips lections around the world. Gi\'en thal Componems. 5ylv:lnia or Phi]ips T"I Il sconductance - 6000 I-IS min hundreds of millions of lubes were manu factured per rear during the 1950$ and ECG.(This was the fo rmer home of Plate resistance - 600 ohms mu. 19605, it is nOt surprising that left-over Sylvania's main factory.) They have no spares are still around. Common types are such listing; that factory is tOtally gone, Mll-4 s,jJJ being manufactured in Russia and maybe prematurely. By the way, 5 Ou! of Grid current: I uAIll"'" at 65W, 4 ,OA China, bUI many prefer "N.D.S." (New 13 companies ignored us completely max al 85W Old Stock) foreither their sound or their what have they gOt to hide? ruggedness. But prices on certain of these Recommended Iwd rt"Sislall(e - 1500- THE 6V6 GOES ('OOF N.O.S. rypes are skyrocketing! Aside from 3500 ohm! for .....am linear OUlpUl. 18-28 the early or industrial types that were Have you tried to buy a 6V6GT Vaic recommends fo rced-air cooling never made in the qualHities of later rypes recendy? Suddenly, the NOS supply ha� above 80 wattS dissipation. The glass tem (such as the 50 and 300B), recent, COIll dried up. The reason is that, although thi� perature must be kept under 200C, and mon tubes are becoming scarce. First it baby 6L6 is not popular in Hi-Fi amps, its the [ube should be mOUllled at least 5 cm wasthe 7591. now it is the 6V6GT and use in classic guitar amps (such as the away from anything else. Ty pical opera 6L6GC. hen small tubes, such as Fender Princeton Rcverb and De!uxe) tion with a 2500-ohm single-ended (ranS Ampcrex 6DJ8s, are beginning to appear guaramees a good demand. The street former has 500 volts plate, -96 10 -110 in collectors' want lists. Yel IUbes nOI in prices for those: circ;a- 1960 guitar amp� are vollS grid bias, 150 mA plate current, and currccnt demand, such as TV rypes or mili rising. So, has somebody bought all thc gives an OutpUt power of 25 wallS with tarylindustrial typc:cs, languish in ware old 6V6s? The Russian ones arc of inferior 33% efficiency. Grid resistor recommend houses. quality, and these amps run at high volt ed is lOOk ohms or less. The warning in ages so the low-cost Russian product gives the data sheet says: "Not using with fixed Unfortunately, convemionaJ vacuum a high fai lure raTe. The situation is get grid bias without automatical regulation tube manufacturing technology is labor ting so desperate that some guitar-tube and capital-intenSive, and greatly benefit� according 10 cmissivity!" which, I think, from The economies of scale. Even in the dealers are either selling those skinny means that they would prefer use of an Russian 6L6s (aclually called 6P3S, and auto-bia.o;. The tube is also suitable for u�e 19505, whccn nearly all consumcr electron ics and milituy equipment tubes, the nOI a real 6L6GC at all) as 6V6 replace with cathode bias, the resiSlOr being in the used mentS, or else selling 6EY6s and 6EZ5s to 470-1000 ohm range at 50 wam. The cOSt of tubes (adjuslccd for inflation) was musicians. The Russian tube was never still higher than the COST newly-manu VV52B is available exclusively from: of meant for use above 400 volts, yel some factured tubes coming out of Russia or people have !Tied 10 sell lhem for thai, Triode Supply Japan, 227-1-101 China today. As those countries phase OUT m:ulting in many fried guitar amplifiers. Kasimada, Saiwai-ku, Kawasakisi, their vacuum-tube military equipment, They seem 10 be OK as 6V6 replace Kanagawaken, Japan; phone 81-44-511- the only signiflcam remaining market for ments, although Ihe bias paims and mher 6343,fax 81-44-511-3492. Priu is new �recei\'ing� tubes is [he audio and (:haracteristics are quite differenl. The 108,000ym Mfh. music amplifier business. Unlcss the usage 6EY6/6EZ5 are ol d TV vertical-driver of tubes in the� areas sustains a massive tubes that JUSt happen to be prclry good incrcase, the existing factories may not and have 6V6-like pinouts. (They are only ha,'e the economic incentive for keeping rated for 315 volts max, but ( won't tell thccir production lines open. At that poim. any guilar dudes if you won't.) RUlllor since there uill would be a demand, small has it thal somebody is trying to staft up a er factories would make tubes on a much new (Ubi.' factory in the USA (not Western smaller scale, charging very high prices. Electric). They intend to keep il a secret Current examples of this include umil they can produce some good-qualiTY Richardson Electronics and VA le. samples. The guitar-amp market is every So, today wc are faced with a finite thing TO them, as it dwarfs the high-end market; so don't expect any 2A3s. BUI I and shrinking pool of dcsirable N.O.S. uncertain wonder if Ihe first tube they make will be tubes. and an source of new a 6V6GT. Maybe if we ask with big IUbes, many of which are no! as good as smiles, they will also make somc 7591s. the N.O.S. rypc:cs. Vet how many Times do Have you ccver noticed how similar those you secc guitarists burn-QUI a �t of IUbes tWO IUbes look? after one or tWO concens, or audiophiles WE 205D who replace all their tubes every few VACUUM TUBE VALLEY • P THE MAGNUM 5 NGlE� ENDED A M momhs, or inexperienced technicians who 2. Don't leave your equipmcnt on all The Magnum don'' leSt for leaking couplin capacitors the time: (unless rou actually use: i( all the , leadmg w prt:mature tube faij UTes? Or, on time-like a radio sl:uion). Tubes dctcrio Single-Ended Amp the manufacturer's side, designs that run r.HC with use. On the other hand, don't tubes far beyond their ratings, whether (�rn equ�pment on and off frequenrly. by David A. Wolze thro u h i norance or a belief Ih;u running lurnmg It on and off once or twice a day g li Thi, h rhr first tIInphfitr drwir dr,lglI the tubes hot" improves their sound. is a good compromise. 'Irriclr forvrv. [I is I/orprrumrd fIS 11 sup Good N.O.S. tubes, run conservatively by-sup cOIISrrucriof/ anicir, bflf mrhrr ro within their ratings, should laSt frolll 3. Insread of changing all tubes ar gillf" idrllJ 10 morf rxprrimud comrTllClon 2,000 10 more than 10,000 hours. BUI ouce, replace only those Ihat are weak or a"d duig"rn. - urh. £d. many of the practices listed above aUk impair the sound. If a tube doesn't sound ood, but is otherwise snong, try using it cubes to be: thrown away after only a few � Single-cnded amps really sound greal, III a less demanding location. Often only hundred hours or less. This rapidly but mOSt are low powered and expensive. one or tWO tubes in a unir are very sensi depletes the finile numbn of N.O.S. IUbes Many use filamenrary tfjodes, which are tive to IUbe variations. III existence. expensive, short lived, and hard to inter face. When using filamentary triodes, DC hat can be done? The be.t long-term 4. Check your power line voltage. The filament ower is often required in order )oluTlon� would be for a revolution in al'erage line voltage is now bigha than to con{ro[ OUtput hum. But apparently manufaCTUring techniques that would whar it was when rnost older equipment {here is nothing else available; tube manu allo,,:, TUbes to be made inexpensively in was designed. If it is tOO high, reduce ir facturers wellt 10 beam power tubes in the rebtlvely small quantities_ The progress in with a Va riac (variable Iransformer) or a '30s, abandoning {riodes for audio. Then �smart" manufacuHing may allow this in filament transformer connecled to cancel the SE craze hit, and [Q gC'1 linear output the near fu ture. But until then, here are some of tbe line voltage. h is best to check devices, we had to use TUbes designed with some recommendations to the vacuum the filamem vohage right at tbe tube sock 1920s lC'chnology. tube users and equipment manufacturers: et. (This should not be a problem fo r reg ul:lled filament supplies_) The Design Challenge Tu be Equipment Manufacturers: 5. Don'r replace vacuum tube recli I wanted 10 design an SE that had 1. Know of all of a tube's maxilllum fiers, especially hearer-cathode Iypes (such high power, a simple design, an,1.II:r rhat rlings, and design within them. An espe as the 5V4G or 5AR4/GZ34), with silicon � good SE sound using inexpensi\'e compo Cially common problem is running Output rectifiers, unless you compensate for the nents. As a practicing elC'ctronics C'ngineer, retrodes or pentodes in triode- or ultra-lin increased B+ I'ollage and provide for a [ must meet similar goals whC'n I do ear connection with a high B+ voltage, B+ turn-on. delayed desi n work on the job. Doing this for ;1 which often brings the screen voltage and g hobby amplifier was therefore second screen dissipation far above their 1ll3xi 6. Avoid manufaclurers Ibat have a natufC' fOf rnC'. Of course, there were :,1 mum ratings. repUla,ion for building unreliable equip couple of tricks involved with pulling this ment or equipmC'nt that �eats" tubes. . 2. Run tubes conservatively. Tubes la�t of[ Tricks are also pan of C'ngineering, a lot longer if they arC' run below Iheir These n�commendations will help pre OthC'fwise the Illan could rC'place me with maximum ratings. serve the supply of good tubes so that a machind!! more of us can C'njoy the benefits of tubes! 3. Make the ci rcuit in)ensitive (within reason) \0 declines in [he TUbe'S emission ancl transconductance. Don't require spe cially sdeCled tubes. SE Amplifier 4. If you find that running tubes at high voltage or high curren! makC's them sound bettC'r, it may be that you arc JUSt moving the operating point closer 10 a �sweet spot." Tryseeing if l difTC'rem 10ld impedance Cln achiC've the same effect. 5. Delay [he B+ turn-on until lhe tubes are warmed-up, especially for power tubes. 6. For products with small production ��ns, c Hlsider using sorne oflhe neglected � . . . I V or IIldusmal tube rypes. I here arC' still 1015 of them around, and many are quite good. Tube &Juipment Users: I. Be sure your equipment i� in good )hape, and properly biased_ If a panicular tube location fails frequently, bring the unit in for repair. VACUUM TUBE VALLEY • - THE MAGNUM s NGLE- ENDED A M P cuits' in the El core. When onc: is starting from scratch, the 'E' sections would mere ly be inserted into the coil without altcr nati ng them. The resulting [wo-piece core hlS the air gap introduced by shimming rhe T 5«tiOII from the 'E's with a non magnetic malerial. Fig/ut! 1 Tramforuur ModificlltiollS Replace bolts and lighten belore cutting CUI ., Cut lt2 @J @J H8mmond 1650-W Converting the Transformer BEEFY units arc JUSt the ticket for high @ @ power (Ube amps. Rumor has it that these \ The first trick is to convert an illc)!: transformers arc used in a famous maker pensive push-pull transfo rmer 10 accom I \ guitar BASS amplifier. Hmmm .. modate SE oper�lion, Isn'1 it ironic Ihat It i� nOI ca�y 10 cleanly di�asscmblc the core of a push-pull lransformer. The air while a single-ended amp needs a much The 1650W is supplied as a push-pull gaps must be introduced by cutting larger OUCput tr:.msformcr for a given unit. It has the standard 'El' iron core through the iron with a hacksaw. It may power level, all the big iron our there is configuration . It is built by first winding be possible to have a machine shop do for push-pull??? WHERE'S THE the coil and then inserting the 'E' sections this. Remol'e the end bells and replace BEEP?? If one wants 10 get a beefy out into the coil and capping the 'E' with an and tighten the bolts on the core, to pre put for their SE amp, a push-pull unit T. The orientation of the 'E's and Ts are I·ellt il frolll delaminating while you CUI must be convened 10 SE. alternated, fo rming a solid iron core to it. Make tWO cutS; one on each side of the build a push-pull lype transformer. The I-I ammond 1650W outPUt is the coil, as shown in Fig 1. The mera] is soft, transformer that I chose for my Magnum To conven a push-pull tramformer to bUI Ihere is a LOT of it. It took me SE amplifier. Rated at 280 watts and single-ended, an air gap mUSt be intro threehours 10 make the tWO CUIS. 1900 ohms primary impedance. rhcse duced into each of the ('. ... 0 magnetic 'cir- • 33011 10 ...... 2 x 6BM81ECl82 . " ._- •• - 160V The Magnum SE Amplifier b� Dallld Walza NO'''' 1 . '..... "'" ... 2 wan •••_ '''' �no ",,,,,�r r.... ''''' ....(conner;te VACUUM TUBE VALLEY .. THE M A G NUM SINGLE_ ENDED A M P Bui.lding the Amplifier aoov 41\ A8 Testing the Amplifier The Inulting transformer tested tubes as str.light pentodes or uitr.l.lineOlr, was With the amp built, the bia� pot was with a small signal on the primary. with excellent results. The EL509/6KG6 turned down and the power supply was Frequency response was within 3 dB ;u 10 or other similarly-rated sweep TUbes could anached and slowly brought up with a Hz. [ figured Iha! the power bandwiddl be used, but are not as rugged as the Va riac. No smoke was seen. so bias wa� would be good down to about 30 H1. on 6P45S, so be cueful. advanced until an average of 500 milli this rransformer. The high frequency volts was seen across each of the 4.3 ohm response was improved, as the reduced Second, Tim de Paravicini recently had cathode resistors. This corresponds to a inductance r:aised the resonant frequency. his 'enhanced' screen grid driven circuil total plate current of 470 ma. My Heath (Resonant frequency was over 200kHz.) published. This elegant idea will only IG-18 330B work well with sweep TUbeS. Not only is oscillatOr and H-P tubed dis tonion analyzer were then hooked up to Converting TVSweep Tu bes the sound improved over pentode 0per.l. tion, but also the front cnd circuit com the amp, along with the scope, to gel the The second trick involves th" use of plexity is cut in half. The BEAUTY of fo llowing specs: TV sweep tubes in a novel configuration. this screen-grid drive idea is that the clo�e have been a fan of sweep cubes for years. (pl l "ohJge): 330V (lee "hematic on [ screen grid spacing in a sweep TUbe, once Eb � � Built like miniature tmnsmi·ting tu�. thi$ page for a $uggemd power supply). considered a disadvantage for audio appli Ib ru ed uniu represent 19605 tech (plate current): 600m.-'. (tot,d. including these gg cations of these tubes, is turned into an nology. Their ;advanced materials and pre from end current) advantage-!!! Now, the high perveance and cise consTructioll are light-years ahead of rugged cOllSuucrion arc combined with VOUI ;1. clipping - 65V p-p acro�, 8 Ohms those 1920's fi!amentary rriodes. They are good linearity. No other TUbe type can waIlS rugged, beefy, and no one fighrs me over (68 R...\oIS) hold a candle to the lowly sweep tube them at the swap meets. Indeed, the last DiSlordon at 50 WaItS 1.5% (mo.dy operated by driving audio to its screen - Antique Electronics TUbe sale fe atured 2nd harmonic) grid!!! 21 GY5 sweep tubes at the lofty price of Dislonion al 8 WailS 0.4% (mo.dy lnd cents!!! Two recem developments have Application of the scr«n grid drive i� - SO harmonic) only served. to increase my desire to use simple. The control grid is tied to the sweep TUbeS in my Magnum amplifier 10K cathode through Ol resistor, and the DislOrdon a. 0.5 Wall> - 0.5% (mo�dr designs. screen grid is driven by a direct coupled noise:) cathode follower. The screen grid then First, Svedana has come OUt with � Power .1· dB 10 10 actS as the control grid of a low mu pOwer 1l.1Ildwid.h J - 30 Ht really nice EL-509IGKGG equivalent. the kl-h. triade. Its plate resistance is about 2000 6P45S with limited availability. This tube 12 ohms, and at waits out, distonion is Frequency Rcspomc @ Wall. _ 20 Ih. 10 is exuemely rugged, with a heavy glass 1900 8 under 1.3% imo a ohm load, with 50 kHt .1- 0.5 dB envelope and :lheavy duty he:lt('T and 300 I the plate at volts and the cathode cllhode constructiotl. ha\'e built sevcr.ll Fr«Ju�ncy Responsc @ I \'\;'all_ 10 Hz 10 SE running ISO mA. push-pull :lnd amplifiers using these 100 kHz .1. 0.5 dB VACUUM TUB E VALLEY :. [NTERV E W w T H TEnR Y BUD D N G H SqUllfC W:l,ve R<'$pon$f' _ No overshoot; The illcrtdiblyfilii and pownfil sound o TUBE GUITAR AMPS, f :l.IXlUt 5 cycles of 200 kHl ringing 31 the tlu '60s em Manhallsp la 'ed an essmtia tx,ginning the pulse; peak ampljUlde of J of interview with Terry of rof� ill the d�velopmem o li llli Hmdrb/s ringing aoom waIts OlUPU( An Budingh f 2%. 30 @ I Gujtar Pl aYerMa gazin e innovative style. I doubt he would htlllt kHz. crtated tlu same incredible mllsic withOllt Listening Te sts by Charlie Kittleson a raging stack ofManJJlllls. Also, the era Tw ill Reverbs are bltu"k jacttI f:tllder Three listening tCSt� were held tu cval CK - Terry, are vintage guitar ampli �reat Tor cleaner, less aggresive sound. It�tC the new Magnum SE amplifiers. fiers still a hot item amongst profeSSIOn 7/)e [m erknown British·Hi Watt amps First, [ listened 10 them myself. This was al players? are a/so illcredib/� sounding. the first time that I had heard DECENT . BASS from an SE amp. Yel the grace: of TB- Vrry flllICh so, csf.ecially o�r du CK - What never amps achic\'e: that Ihe lOp end lel nle know that this was a last fowyeafs. \�tm mllt rying to figl lrt: �vintage" sound these days? single-ended amplifier. 0111 why tI of new amps do n't 10 lmd a, lot TB good. The vintage amps have a rertain - Tlu Kendrick lilleo f amps, Next, the ;amps were brought to richlless (lIId complexity of tOlle, while which really was the fint of du �bou+ Vacuum Tube Valley for a critical evalua tique� amp companies starring ;'/ ,he Ime malll lIewer a,!'.l. s sound olle dimensiollal, tion by a group. The panel was was duly haffher t/llds tiJJer. 1980's. Trailllllreck amps, made byKm impressed by the Magnum SEs. Solid bot Fischer, SOU/Id amazing. The emire tom end backed up by incredibly deuiled CK- What is so special about the MatcMm lillt, upecially the 100 WlIll mids ;md highs were enjoyed by all in the sound of older guitar amplifiers? Super Chief and vox AC-30 impired listening session, which iaS!C:d three hours. DC-30. Matchlm fofllllrrs impeccable TB 011 (Speakers used al vrvwere Klipsch - They limply have a 1/Iore com poillt-ta-poim wiring termlllalst r s l as ip Chorus Is) pel illg sound. They are rypically not andp remium tubes. Hoiltllld AmpliJi! rI harsh. tit'" or comtricuds oullding as of Virginia produces tI qlltdity clone of the Finally. Ihe :amps were brought 10 � many oJ the lIew tube guitflr amps. Th� 1959 Baslman. Victoria Amplifia large outdoor parry. (Oon·1 Iry THIS with older amps have more lonal coloralion Compall] ofIll inois builds nn awesome your wimpo 8 wan jobs!!!) The speakers and charflcltr, possibly caused by tlu aging soundint lote '50s tweed &mdmaurr used at the party were DUX Soundfield IV components. Everythillg in the signal desigllJef/wrillg3 -10�/peakers. lOllY c3binets, dosed box with a volume of fo ur pmh matters. Tubes, resistors, capacitors, BrUIlO and Dr. Z hod, makt retu VOX cubic feet. The boxes were braced and wire, tram(ormen, and esprciaiiy sp�akers, AC-30 illspired variants. AIf. af these modified so that the woofer fires forward. all have the ir special cOlllribution to the amps foature quality point-to-poim The woofers were JBL 0-140 with sOllnd. Most oftbe older amps are very wirillg, ulect components, abo� average crossover at 1000 Hz. The midranges basic ill design and construction, and IIIICll/lm wbe qll(liiryand mrefulfine 11111- were 4-206 125 Hex ETON with a first with 101le, less is more. The quest for ing to get the beit tone. order crossover. The tweeter was a great tOll� is an art tbat perhaps trall Phillips A0216Q08 ribbon tweeter with a scellds science. CK - What are some of the new first order crossover at 5000H"!. trends in modifying guitar amps? CK - Wha( are: 50me: of the favori(e Through (he heat of the day aud well low to mid- power guitar amps of the TB - 71)e rrmd is to de-mod and imo the night, the amps played on. tOp recording anists? futore dum to original cOlldition usillg People just ;!SSumed that this was pro exact original Cllpacitors, retstors,i trallS TB • audio gear; it effortlessly handled MflIlJ of the pre-1965 (p re-CBS) formen and IIIbes. These olderamps Gershwin as well as the loudest disco heal. Fender amps illcludillg the Deluxe Reverb SOl/lidjust fille the way they �re origi Ilnd Super Revt'rb. The 1950s era tweed Ill/fly duigl led. PkIJm l/re gmillg allllIJ , D;l.ve Woh.e is a San Jose, C;l.Jiforni� Deluxes alldthe (wud Basmlfln amps from addi ll g /1/lOthergaill sll/ge, ijfocts ba.w:J electronic engineer. sOlmd guatI Actually, aiithe tweed era loops, nc. to o1d�r amps. The currem amps ca" sound illmdib/� when prop �rjy trend is alll9from the digital rack set lip with good N.OS. tltbcs, etc. DJ mounted eDects prOCf!SSOff so prevtllem ill cOllrse the VOX AC-30 uts the stflndtlrd tlu '801 alld more towards the �Jtomp for liveLy. ringillg lone with itS rt1111lrkably box" e./Jr cts that were COIIIll/on ill the ·60s chimey treble. Gibsoll amps are real slup (/lid '70s. Vimage rfficts boxcs art becom ers 1I0W. The smaiier combo amps using illg cail�cribles. cathode bias circuits, poim-Io-poim wiring, 6V6 or EL·81 tllbes sound gretll. CK - Does re-capping an old amp The slll(dler tubes Can "s ing" and "'ioice" re:aliy change the sound that much? notes better at lower volllmes. TB - The power sup.7-1 tlecrrolytic CK - What arc the favorite: larger mpttciton ha� a short, Ilite lift . Tht:lr m amps used by rock concen artists? replacemem is illevitabe . Diffir t elec trolytics bave diffirmt sOlmds. COllplillg TB - TlJe '69 to '73 Marshtlll 100 mps cOllfribllte sigllificantly to all amp's MlIl SlIper Leads using .[ - EL34s and soulld. Whm JOu re-cap all oldam p wit/) poim-Io-poillt wirillg. Also the '65 to '69 sa] PolyproPJlme Sp rague Orange Drop "Plex;" serits M,mballs. The mid '73 capacitors, 11 definitely changes the tOlle. t/lld IlIter amps tlsedprillled circllit bOlmis 77u complexity and color washes OM. For and lack some of t"� richness tlndcharac ret,lining the lIilltage Fmder, SOl/lid the ter. The �Qrlier amps sound more aliw Gibsoll CH- lOO GlIil4r Amp ]ellow As trtJl/Iall dt he blue plllJtic wbll- and ha� a bigger, mort comp/�x 101le. VACUUM VALLEY TUB E • INTERV E W w T H T ERRY BUD 0 N G H Inrcaps a" I'unltial. Also, carbo" compo TB - Th , Cl'Ilall'x KT-66 has till'most abo I'XCI'ifl'lll. Thl' I1l'l/Jf'r EL-84 RlIssiall SI'llU sition misron liJu thl' AIII'1I-Bmdlry !lpts incrl'dibly rtfi nrd of midrnngl'prl' typts lack ,he ric/moJ, compll'xity, rtfi f/t � . IIl1'm IJI'lp to achil'vl' thl' "vimagl' tOlll'. lJyo u Sl'lltnlioll find dnail. Th e Tl lng-Sol 5881 and balllllCl' of thl' oldl'r tIIbl'S. lIIam 10 "clo nl'�thl' oldsOl/lid yOIl /lud to bas a grind, twang tblll sOllluli great in USI' rlJI' oldpuru. Modl'm parI! all sOlmd I'arly Fl'Ildm. Tb, R01 6L6GC, round diffimllfrom Ihl' SllIJ. tOp, "blllck pllUf'J�from tbr Inu '50; and old f mrfy '60s arr I'spl'cilllly fidlIInd rich CK- What do yOll think of the Ilcwtr sounding. Th, S lvanias havl' 11 tight, y f Chinese and Russian tubes in guitar firm bottom alld11 bard, Stif midrangl' amplifier applications? lI11dlOp. Thr Milliard EL-371 art incrd ibk - sOl/ienlly,duirt bmllun a Mullard TB El/m btst I'xamplts cant 1'11/'11 - tlu EL 34 alld GE 616 - strong alldpunchy brgin 10 compa" 10 tlu sound of lhl'grrat wilh good riclmns IInd complexity ill tlJI' oldlubts fromrlJI' past. Thr RlIssian tIIbts Illck the richly complex and musical mid mid-rangr. TluSovuk 5881$ havl' a mllgr, balnllCl', alld purity of 10111'. Thry cll'lln, co-Io rlm midrang( IIIld slicry top. havl' a higher foiiurl' mu t"all thr villtagr Thl' buur amp dl'siglll'n are rrdtsignillg thl'ir circuits to compf'llsall'for rhl' short • N.o.S. stuff Thry ul/'aroutfosur. TbI' • Russiall 5881 has bl'comr tbl' dl'focto comings of thi! rllbl'. s/(llldardfo r 1I1'W tlIllp buildl'r;, sim l CK A - e n p y - lot of guitar amp s, especially CK LaSt, bur c rtai ly !lot least, buallSl' tlJrre is 1I0thing buur llI.NliUlbll'/1/ Marshalls use the EL·34/6CA7, which what 6550 type is your preference? mass qllamitil's. Thl'Ch itit'll' Olllpllt tubrs ones do ),ou think perform best? haw rvm higher foilu" raw alld shorur TB - Tlu 'lung 5016550 (mllY br strviCl' lift tvan thl' Russians, ,md rvl'll TB - 111 Mars/Jalls, I rtfo r Mullnrds, brandl'd GE. RCA, /?aythtoll, m) cokl' sound chusirr. preferablytl1I' mr/y ml'tII[ baSl' lIaril'ty. bottle typ e. Thry havl' the right IOlIal bId· Th ryhal ll' 1111' most compll')" and liw/y allCl', complrxity, ufi nl'mf'1ll, I'xqllisitr uppl'r midmllg( III/dlOllltr treble. Th ry dl'lIIil, SI/Jf'rt "ppl'rmids, "'�hi ghs 1II,d hlllll' Ihl' incrtdibll' capllbilityof sounding air. The GE 6550As soulld lIltDllt 11ft ml'an and lW(f't III tl1I' saml' riml'. [all'r flOt as duaill'd or rrfinl'd. 'hI' nl'w Milliard o:amplts rttnin thl' pllnchy SVl'tfllfll1 6550B is also showing iOmt midflmgt, bill arl' 1I0tiCf'IIbiyless I'xciling promiSl', bllt billSstllbililJ and rtliability ill thl' trrbll'. TI)I' CE 601_ 7s can sOllnd 'lr� still qUl'sfiollabl, good, but art /)IIrd(r, stiffir alld tigh ll'r, witb Im midrflllgt pwh. CK - Terry, whal are some of the trends you see in the tube guitar amp CK · Man), of the smaller vimage business o\'er the nexl five years? 10-20 wan combo amps use Ihe 6V6. TB Wh ich ones do you like? - \171'art rounding thl' cornl'r 011 IIJI' mbl' lImp Tf'vival. I ltr more boutiqul' TB - The post //Jar RCA ytpt with thr limp buildm popping liP . Why? Ikcausl' gm y graphiu coming insidl' til t bottle. thl'rr is I/O way 10 ma tch atUlltion 10 CK - Let's t alk about the best tubes Th ry Jlmpfy sOlllld righl - rich, foif, dttail. MallY of tIme halld-bllilt lImps arl' fot electric guitar applications. What smooth and crl'amy. Tb I' othl'r typN tmd also illdividllllOy runl'd alld pl'nollaitZl'd are your fa vorire vintage 12AX7 tubes ill to lack 101ll1/bllll lllet. to match the plaYl'r's fllJ lr alld stylI'. This guitar amps? is impouibll' to do with mllssprodllcl'd CK - A lot of newer amps arc using prodiiCtJ. TB - For Mllrsh,dls, Ilikl' r/JI' rarly Ihe EL-84/6BQ5. Wh at are your faves? Milliards with thl' uami ill thl' gla ss 011 Ihl' CIIffmt trrlld of "c(/lIoll TB - The mOICI' of llll EL-84 is its H9td1y, r/JI't op of lhl'tubl'. Thl' tarly /ii l'-plau izillg t)(cllISsics of the past wilf dl' wlop rg inc"dibfy livl'ly and complex IIppl'r illlO II mort crrll,iw lrtlld of I'xpl'riml'fua MllllnrJs can soulldI' sp l'ciallyfi dl alld midmllg( alldt"bll', combi'lI'd with a rich. Tbry allhaw IV I'ag gmsiw, for tiOll with diffirrm, ulIll$ltal and 11(1(1 mbr smooth richlll'SJ ill thl' banalld lowtr rypts. circuit hybrids alld mch. Lds lIIard, driving midra llgl' ifi lll is so tnt/llial mids. TbI' EUrOpl'1II1 typts illciudillg 10 rell'am flu 10u 11'SlO1/J of flupast, d)(1l Ihr Manhal1 Jouna. Fo r black foCI' I'ra Mllifard, TtlrfimJ1(11 and Ampm'X, "if Fm dl'r amps, I likl' the smoolh, s/Wl'tly continlll' to dl'vrlop ana rl' {lllt thl'art of sOlllldsp l'ctllCfllflr. Thl' GE £L -84s arr \\1t> dtlicatl' sound ofa smooth or ribbed plait amp building. shouldail strive to SIIr Tl' ll'fimktn in tht {lrst g"ill s�" t. For r/Jr pass ,hI' classics of thl'pllSl, rathl'r than plMSI' ;,wtrltr, I fllrl' tht rich IIlbll'SS ofa bl'ing coml'llt with IIIl'rt'y imitfltillg r/JI'm, nul/chl'd 7img-So! 12A'l7. £s or RCAs Tht fJlltstfor gum t01l1'is nl'ver mding. 1/11 arr rxullmt choiet for th, Olhf'r lImp . Teny Budding. based in Livermore, CA stagl's. For thr tW(f'd f:tnder lImps, I prr is a performin� guitarist, amp technician. ftr a CE 5751 ill thl'fi rst gain stagl', or a writer and equipment reviewer for Guir'lr 12Al7which has a ckalll'r, mort dnail(d PIilyr MlIgazifll', a Miller Freo:man sound with "lncier· highs. 12AX7s bav( Publiallion. too much gl lillfor a twud'sfirst Sla I' and g - sacrif/u clarity. dl'tllil alld TIIUlIICI'Jo r vol . Guitar amp pholOs courtesy Groove uml'. Tubes amp collection as fe.nured in TIN Tubl' Amp Book CK - '!hry, what about 6L6 typt: tubes. Which ones do you like best? VACUUM TUBE VALLEY TUB E MATCHING OutPUt Power for differential amplifiers CO\'ers nearly all Tube Matching In power amplifiers, it will be fo und areas: idle current, transconductance, mu, by John Atwood [hat some tulx:s have a higher maximum and manufanuring bal<;h. power than others. Oft(:n, this is caused Differential amplifiers are also used as This article is a follow-up to the VACUUM TUBE VALLEY .: lower the overall distortion by eliminating when Tim Eding and I bought a large Large-signal matching can be done by also the evcn harmonia;. Howc\'er, (\'cn har quantity of EL34s and GBQ)s and deter taking measurements aT higher vohages monia are the "bener�-sounding harmon mined to find the beSt way to match and currents, and insuring that matched ics, and the odd harmonics, especially the: them. tubes have the same characteristics at Ihese high-order ones, give a harsh, hard sound. different operating points. Be careful not Thus striving (Q perfecdy balance tubes in Burn-in to exceed screen or platc dissipation rat a push-pull Slage may reduce the total dis Most lub.:s will shift in charactc:ri�lics ings for 100 long while doing this kind of IOrtion, but leave: the �sonic imprint" of over the first few hours of use. [n the past, test. odd-order distortion. tubes for sensitive DC amplifiers were often run for 48 hours before being Dynamic In-circuit Measu.rements BalancM idle: (:urrcnt is imp'Onam in shipped. Tim Eding found that in Ihe One way 10 match tubes is 10 test eliminating tr.msformer sawr.uion at low power tubes he tested (Chinese and them in a push-pull amplifier. DC balance signal levels. This is where the amplifier Hungarian EL34s and Yugoslovian can be tested by looking at what freq uency spends most of its time, so is rhe most 6BQ5s), the DC idle current would gen the core saturates. This is done by :lpply imponam. Matching at large: sign:.t levels erally stabilize within a few hours of use at ing a sine w:l.ve at full omput into a is also needed in order 10 prevent �rectifi normal operating current. We decided on dummy load, and lowering Ihe frequency calion� effects if the tubes arc unbalanced. a burn-in time of 12 hours as a good com until the sine wave becomes visibly dis This rectification will cause an unba13nced promise between stability and overall torted. With good uansformers, this is DC la flow thar is proportional to the sig throughput on our test fixtures. Not all typically 40 Hz or lower. Dynamic: m:tfch nal level. tubes stabilize in the same way, so rub.:s ing can be done by selecting pairs of tubes that give the minimum 2nd harmonic dis that afe matched without a burn-in arc . TuDe 'l likely to be unmatched after a little use. tonton. Tu be Testers In-circuit matching, as described For most rub.: u�",o, the only piece of above, can give good matches if the tuoo •f equipment that will give a quantitative arc matched in the amplifier when� they will eventually be used. However, some •£ measurement of a tube is a tube tester, so it is pretty common for people to match special equipmem is needed, and bec3usc tubes on a tube teSter. Perfectly matched of possible imbalances in the amplifier, the tubes should give the same readings, but tubes may not be well-matched for use in so can some unmatched ones. This is other amplifiers. It is difficult to match more dlan JUSt a pair this way. shown in Figure 2, where tWO triodes with identical mu but different transfer charac Curve Traeing teristics give rather different idle currentS. The f:lslest way to march tube� over Plata Vo�a!l'" Oparat;n.g voltage Figure 3 similarly shows twO different tri odes with (he same transconductance, bUl their whole operating range is to use a different idle currellls. Since most tube tube curve tracer, such as The Te ktronix f'glll"t! 2 Same I"", diffil"t!/I! C/jr'�11t testers test for transconductance, not DC 570. The characteristic curves of rwo current, it is dear that tube testers are ill tubes can be visually compared on :I Cln: The degree of matching re:quired in suited for matching tubes. If rhe curves match up, then the tubes will push-pull output tubes depends on the be lIl:ltched over the entire operating sophistication of the: bias and drive cir range checked by the curve Hacer. It is a cuits. If there is no bias adjustment (as in litde hard to get aCCUrate quantitative most cheap amplifiers, as wdl as some Tuoo '1 information off the screen, so a good way receivers like rhe Fisher 500), or ;l. single •I to match tubes using a curve tracer is to bias adjustment per channel (such as in •� first run all the tubes to be matched the Dynaco ST.. 70, Mark Ill, and Mark through a static DC teSI, as described IV), then the overall matching of output above. Then pairs with the same bias tubes for idle current is critical. Any points C:ln be pUl OntO the curve tracer. unbalance in idle current will cause unbal They will often be a perfect mateh :It thi� anced DC 10 flow in the output tr::I.nS point. [f not, chose another pair with a fo rmer. If there is a bias adjustmem per similar bias point. E.ventually, )'OU should mbe or a bias balance adjustment (some be able to make matches of most, if not times called DC balance), then matching all, of your tubes. of idle CurrentS is much less critical, and Figures 4 and 5 show rhe characteristic JUSt overall similarity in characteristi!;$ is Plata VOIt'II' needed. If an AC balance is provided cutl'es of f"\\lO different KT-66s with simi (which can alter the amoum of drive volt lar current at a fixed operating poim (at Pig",.e 3 �IIIII!gm, age to each side of the push-pul! stage), diffil"t!/IfClI,nf/lt the center of rhe screen), but different then large-signal balancing is even less characteristics elsewhere. Figure 4 shows Static DC Measuremems critial. Unfortunatdy, it is difficult 10 and older British KT66 (with the gre), C'.If effectively adjust an AC balance control The beSt wa)' to m:ol.{ch tubes for idle bon inner coaling) and figure 5 shows :I without the: use of a dislOrrion anal}'1-Cr. current is to PUt them into a teSI fixture later (perhaps mid-1970s) General Electric that runs the tubes under identical condi 7581A1KT66. On both curves, the grid Techniques fo r Matching tions 10 those that will be encountered in voltage Step was 5 volts, the X-axis is 50 V the amplifier, adjusting the bias for the per division and the Y- axis is 20 ma per The fo llowing techniques for tube dcsirro current, then recording the bias matching were developed several ),ears ago voltage needed to achieve this current. VACUUM TUBE VALLEY • l E A R L Y CINEMA SOU N D division. Although f� irly well matched should be a;;ked of a tube dealer about around the center, they d('Viate from each Iheir malching process: 1927-34 WESTERN ELECTRIC other at both Ihe high and low current lARGE THEATER SOUND I. A.� the tuixs b rned ·m? for how long? extremes. u SYSTEM An: rh� v burn�d in under load, or are the �orlle tips for matching using curve fi l arnen'u simply heated� (Healing only the by Charlie KittlesoD !racmg: filamem doc:sn't stabilize the tuhe.) Although recorded mu�ic '·.. a� played When matching a pllir of mbe), either 1. At whar plale and s.crun ,'ollages 2fe rhe through amplifiers during MsilemM motion m t h Ideall should � (urn on their heaters at the same lime, or tu�S a c ed! ( y Ihac pictures throughout the mid-twemies, the lose 10 whal your amplifier uses.) allow a long time (several minutes) for c first widely accepted production to (he cathode temperature to sTabilize. J. Are the 1lLbes matched 31 a single optr:l.ling emplo), rhis new technology '-r.lS the Wa rner Brother 1927 production, "Tb", If the tubes wi ll only be used in tti poilll or are they matched �t multiple opt'. Singer. � The mp i er system used ode-connected mode, it is OK to triode aling points! (A compUlcr- In the middle of (he rack is the Type 42 amplifier/driver using four Ty pe 205 triodes thal are round "tennis ball " shape with a rip on the top. Two of the 205s were used for the full-wa\ The Wcslern Electric 43A power amplifier WlIS inrroouced fo r [beater use in late 1927< It featured four-type 211 FigUN! 4 Old British KT66 FigllT'r 5 GE 7581AIKT66 VACUUM TUBE VALLEY • EAR L Y c N E M A sou N D THt.URE WORN "O�N (;ONT"OL THEATRE HORN ..OIlN Kty OUT '" ::, :: CURReNT "'UER ::;: : �.� .....,� ...."0 .. 5 4t-" A"'''",''.'----_ WE555 or WE-242 transmitting triodes in the �'""''' '" circuir. Two of the tubes wer� us�d for WUTCRN El..tCTRlC 20� TVI'( full-wave DC two were V... CUUIoI TUeE! ' ... M ....�' r�c(ification and used for th� power OUtpUt stag�. CURRENT "'(TEA Th� 43A push-pull triod� amp produced about 20 wans in Class A with a frequency -.""me" 'W'TC>! _��,:,��:'."'�',''':',l R'C 2" TYH: IRtCnrl(R' -."'m,� 'W'TCN 43-" A""" "" ----_ 41,42,AND 43 TYPE AMPLIFIERS, AND OUTPUT "'\OI1SC from 50 to 10,000 Hz. CONTROL PANEL ) Ah lough these sp�cifications ar� not phe nom�nal now, they w�r� in the lal� Twenties. The 43A weighed in al ovcr 175 pounds. Comrols included a power and standby switch and a plate current metcr. • The box on the bottom from cover con tains a hug(' capacitor bank. People who have lislened to the 43A compare it to a "big Brook 1lA" sound or similar 10 a low volume Altec Lansing I 570A theater amplifier. The mids are big and sweet, but the bass is semi-mushy. New The 43A!iCTured came from the York area an was probably used in one of M(ij,U.TOR the early movie palaces in the Big Apple. The OUtpUt uansformer in rhis panicular 43A was r('placed by a later A1tcc-Lansing unit that increased (he power OUtput and WE·203 improved the frequency response. VACUUM TUBE VALLEY l • EAR l Y c N E M A SOU N D improved the frequency response. The sound for the early movies wa� recorded on numbered 78 rpm re.:::ords thal were played on the \VeStern Ele':::lri.::: Ty pe 203 dual non-synchronous turlllabk (pictured). This system was used before Ihe advenl of the lighl valve oplial soundlrack. The \Vest.;rn Electric horn speaker .y, !<:m used in the larger thealers was lhe Type 16 that was over 9 feel wide. It used fo ur-Type 555 electro-dynamic horn dri vers (picTured). Larger thealers could have used tWO or even fo ur of the Type 16 horn systems. Or they may have used multiple Type 12A Mbig snail" horns with a single Type 555 horn driver. The 555 driver was the electro-dynam ic lype using a field coil operating at 7 volls. It was raled at 10 wans. To this day, it is still the only compression drivtr [haT an go b This and other WeStern Elecui.; e A sp rcial thanks to DOli 1)(11"of Swmyvalr, 01for hi s assistanu in "'(fIrth for tllis {lr/ielr. • WESTERN ELECTRiC audilJ riJl/ipmrm and rlfbrs af( "01lJ bri"g ""lrkrl rd byWb rrrx Corporation, An- Prommadt 11, 1230 PracJmrr Sr. , SlIiu 3750, Adama, Grorgia 30309-3575 43A (back) Earty30s WErib bOl1 mic/'ropll0lJe Ifstd ill Hollywoodalld jI,Irw }o rk so ulldItag�. VACUUM TUBE VALLEY .: v N TAG E BOO K R E V I E W and their charact.. rislics. The first half Higb Fidelity Tet:hlliqltes conrs the anribures necessary for a good FEATURED ARTICLES IN amplifier fo llowed by some hints for rhe THE WINTER 1995 EDI John H,. Newin * Author home cOnStruCIOT. Nexl, Ihere is a dis TION OF cussion of high quality and mode rail.' CO,t VA CUUM TUBE A Vifllllgr Book /uvirw commerci al amplifiers. The chapter con VA LLEY, cludes wilh a section on noise suppressor by Paul J. Bourhin 'TUBE SURVEY - 300B and medi amplifiers and some high qualiTY com um sized filamenlarytriode:!i This review is Ih� in a series cov mercial amplifier componenu. fim Eri.:; Barbour evaluates and tCSI5 all ering books of significancc that wCfe wril Now Ihal on ..has an amplifier and versions of this hiSlOric and tell during the Golden Age of High popular speaker system, the next step is the addi Fidelity. Often onc finds books a gamge audio tube along with newer, relared vari tion of progr m mareria Cha ter nine antS including the SV-8ll and rhe sales, flea markets and used book stores, a !' W- 30. gives a thorough explanalion 0r Ihe AM or sees a book listed for sale through the and tuner circuits then in use with a 'Mclmosh MI-200 - restoration, mail and wonders if il will be a useful FM conclusionary section devoted 10 com modification and listening te51S of this , addition to one's collection. mcrcial apparatus. The tenth chaprer awesome tube power amplifi er. covers records and record players. John Newin wa nft:(1 High Fidelity David Wohe tells us the story on how Naturally, the only record mentioned �re '{(elmiqueJ, 1953 10 be a practical guide he obmined these monster amps, his test records (although recording melhods 10 audio and dispcl the mytbs and mis restoration, modification and resulrant are covered) and no record chang.. rs are information then currently in existence. lisrening sessions. The book was wrillcn for: engineers who mentioned. Va rious quality turntables, wefe not versed in Hi-Fi, home consrruc tOne arms and cartridges are shown. 'FM: Why 88 to i08Mhz� tors of Hi-Fi syStems, .servicemen, opera Chapter eleven explains magnetic tape tors of recording nudios, PA and audio recording, ifS theory, operation and John Atwood explores the early days technicians. The book was designed (0 equipment. There is also an inlcrcsting of FM and why the lower FM band comparison of magnetic tape vs disk became obsolete .. have somelhing for everybody, covering a broad subject fo r a broad audience. recording methods. Hints are gi"en in the choice of machines, tape and related 'GOLDEN ERA- EICO The following is a summary of the components. The final chapter puts it all The famous maker of test equipment chaplers of rhis book: The firn chapter is IOgether. It CO\'.:"fS cUSlOm inslallations . introduced an excellent line of high one of definitions and what makes a good Since Hi-Fi equipmenl is made of indi fidelity equipment ki l5 in 1955. Charlie Hi-Fi sYStem. The second chapter dis vidual componentS, and each listener and Ki ttleson documents and reviews the cusses the properly of sound, the human list.:"ning environment are different, e\'ery entire mono EICa lineup of amps, pre ear and the psychological effects of hear insrallation amountS to a custom on.:". amps and tuners. ing and the acoustical control of sound. The determination of listener requirt This is an imporlalll pan of rhe Hi-Fi ments and technical considerations are 'The Audio Te:!it Bench: DC Meters equation sometimes overlooked by audio discussed. The chapter concludes wiTh philes. Loudspeakers and ,heir technology ideas and examples of CUSIOIll installa John Atwood describes [he DC mea at ,he time are covered in chapter ,hree. tions. Four appendicies follow giving: surement needs of the COntemporary Various constructional aspecu are dis Electrical, Acoustical and Mechanical audio test bench, as weB as describes cussed and related to rheir ovemll anologies, bass reflex equations, design some vintage DC meters. response. There is a nice section covering charts and acoustical horn design data. British loudspeakers. Reproducer enclo After you have read the book, you can try , Plus 11/0" illfaesting and illfomllHiv( (jrtic!ts 011 capacitors, sp fakfrs and transformers sures for bOTh cone and horn loudspeak answering the questions at the .:"nd of the ers are covered in Ihe fo urth chapter. book. There is also a very helpful subj ect from tlJt vrvtdirors Illld c01lfrihlltors. Whar fo llows is a discussion of the indi index. vidual componenrs and how Ihey relate 10 the whole. The chapter concludes with Higb Fidrliry Trchniqllts is a very good some examples of good commcrcial sys book for both neophytes and the sea tems. soned audiophile. Practicality supercedes rheory. There is not much malh and it is Crossover theory �nd t«.hnology are used only where necessary. The hook is .:;overed quite well in .:;hapter five. profusely illustrated with graphs and Va rious Iypes of diSlOrtion including: fre dmwings as well as several good pho quen,")" phase, harmonic, imermodula tographs of high quali,y commercial lion are discussed in .:;hapler six. Hum, equipment. The explanaTions are Ihor noise, and interference are also reviewed. ough and clear without tedium. IfyoII The nexl chapler covers circuils pe<:uliar find a ropy of liJ iJ book, buy it! 10 Hi-Fi such as: compensation circuits, feedback, phase inveneN, tone connols, Paul J. Bourbi" is " Sail Fn lllrisco, G-I expanders, compressors, automatic bias htlStd radio C()I/uro,., hist()rillll, "nd u.lrirrr. Hr and synthetic bass .:;ir.:;uits. These are the has puhlishd IITtidn in Allfiqllt RI/dio circuits ThaT separate high fidelity from CLWifitd alld "faudprriodicab. the run-of-the-mill. Chapter eight deals with amplifiers VACUUM TUBE VALLEY • V A C U U M TUB E VALLEY Are You Into Tubes? Have You Been Wondering Which Tubes Sound The Best? Then You Need This Report! Eric Barbour of Glass Audio and Vacuum Tube Valley, recently tesled more than 1000 audio tubes-both vintage NOS and CUJTCnt production. These tests resulted in a list of distonion readings that correspond to the sound clarity. Now YOU can know whal tube dealers know, Then You Need 1..:.._=---' Tubes Covered VA CUUM TUBE VA LLEY EL-34 3008 6DJ8 7591 6550 2A3 616 12AX7 8417 6V6 A New High Qualiry Publication devoted to the Ben in The lest reports in vrvwere deri\'ed from this raw data! Modern and Vintage Vacuum Tube Electronics. Hi-Fi Amps, Guitar Amps, Tubes, Tuners, Send Check or Speakers, and More! $79 Money Order To: METASON1CS 4 Issues - I Yr, Vacuum Tube Valley 1095 E. Duane #106 S2S US or U5 fortign 1095 E. DUlllt Avt. �I06 Sunn)yale, CA 9oW86 Ho Credil Cards SunnyvaJe. CA 94086 G)one electron'" Prod{/ct� (lnd SerdCI!i>'.. UBT-J S;ngle-Endcd Output Tn",sfonner 160 '- Life in n.. � cl ",*-,a ... !LIbGII Va c::tIuuuon"_1Iw audio 160UU --' � sO inouoI'Y by lIorm. WIII'I IMW eireuit de$ignIancIlI'IUCI1 � �� 160 nla llC econponeni& Ind maten,�, tOO-a are ."..,rIding bell", ltIan ... r, The la • 15 WaU� ,0 Pan, Corw>edion .... l!\i,ve'Y HriOuII-/ in • tun ot.sort way In "'"ongooing ... rcn0I 1he wen!. "" _ Old (NOS)SIod< libel. The CO�I [&' P_ ComecIion tIu �,.,rare •largeI1oct.cl IindL H )'IIU '"l0 would � 10 be �n....ww.; cl"'" .."..,.. 10 1isIong, "'"NOS PCMdinII O'VGI'_ V-'" 01 tOOeI (root10 IIIIIIIionpape<.n-o!I �' lorl), give �I' 1;11 and wel be glad 10 a.nd � toyou, Recycled Tubes - The U.S. Dercnsc Dept"s Finest In aI!dnln 10 ourNOS listing, we also I;I''Y newtymar..tlClu,.,j tIIbes, RAM1...IbI, Ruby. Gold ....."OfIgOrl. GakIen We$I6n\ Elldric, Audio HcmO"ed from g,N't equipment - fully checked GIassic:,SovIeI<". s....w... IIId VilebMg 'la'-'*' abclII ...... 1ICiI · "'" possibliDes...... a 1YIiIIt* " """"'*'pan 0( � OA2 6AK5I5654 6V6GTY 5687 , . For !hose cl 10\1 starting IfomICr.t<:h, rnodiIyinginng, or'O\>II The Parts OB2 6AQ5/6005 7Fa 5751 Connec1lClrO ,IsoI;Imes a w;oe ..nge 01 specililY•• "(Iio.. P'� �rts 10 2C5115670 SAU6/6 136 12AT1/6201 5814 ma.... Ihe _ 01 'fOUl'plojet;:Ia, H you'lt kIoking b SOIM\hIfIg SpI(:i6I, us . .... Cl< � )'OU would"'" ....10ordW soon 10 be 5R4GY8 6AL5I5726 12AU7f6189 6Oeo give COtI'IPIetad caWIOg.us drop Iline, eel 0( r ... _credit.,.,.,l_ inIomIIhon.w.. ... "",/ "IQ,e )'OU 10 OUI'and wallJnlllist chlrge ....SIO US upon1I'IipmtnI . Design Services: �79Q "'-an- Roaa, 0&1<_ 0nI.0, canw. l6H5H THE PARTS (� • Audio deSigns - specializing in tubes T.....,.....(905) In.5&SI F"'-.. (to5) '�'»)M CONNECTION' loIF,"Or TU BE - ,. , --,..,. &.1.1_ =+'- ,. �---.....-- -.. -' ... • F-t ,. to- o ,• ,. l � ,. if ! j , • , ,• Et: , • SveELECTRONtlana DEVICES , u • • Headquarters: Marketing & Engineering: 3000 1=1 8200 South Memorial Parllway Alpine Road - • Hunlsville, Alabama 35602 Portola Valley, California 94028 � Phone 205 882 1344 Phone 415 233 0429 Fa� 205 880 8077 Fax 415 233 0439 • • ,. � * @ � Toll Free 800 239 6900 Toll Free 800-5-SVETLANA (800-578-3852) Pv - LOOKING FOR SOME REALLY GOO D PARTS FOR DH. TUVE AUDIO? AucIob."OI�Qrp 2.2JSOV. $19 .If200V, SS .561200'1, S8 " .001/4OOV. 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TEMPE, AZ 85283 • (602) 820·5411 • FAX (602) 820-4643 The company with the largest selection oftubes, components and books! WE HAVE THE PRICES YOU WA NT...... FOR THE THE TUBES YOU NEED! 6eA? (SQVTEK) S8.90 6L6GC (SQVTEK) $3.60 6550B (SVETLANA) $22.00 SeA? 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RCA RECEIVING TUBE MANUAL B-654 $10.95 GE ESSENTIAL CHARACTERISTICS 8-377 512.95 SEVENTY FIVE YEARS OF Vl/ESTERN ELECTRIC TUBE MANUFAC TURING 8-634 $16.95 RCA TRANSMITIING TUBE MANUAL 8-676 $12.95 PRINCIPLES OF ELECTRON TUBES B-693 $34.95 SAGA OF THE VAC UUM TUBE 8-376 $18.95 SEVENTY YEARS OF RADIO TUBES AND VALVES 8-365 525.95 HISTORY OF THE BRITISH VALVE 8-641 529.95 THE SEARCH FOR MUSICAL ECSTASY B-684 524.95 COMPLETE GUIDE TO HIGH END AUDIO 8-687 $29.95 MULLARD CIRCUITS FOR AUDIO AMPLIFIERS B-655 $16.95 THE VVlLLlAMSON AMPLIFIER 8-560 54.95 AUDIO FREQUENCY DESIGN 8-679 $19.95 THE TUBE AMP BOOK B-581 529.95 THE DESKTOP REFERENCE TO HIP GUITAR AMPS 8-663 526.95 THE ULTIMATE TONE B-695 555.00 We offer prompt service and delivery! We accept orders by phone, fax and mail. We accept Visa. Mastercard and American Express. $10.00 minimum order; add shipping cost and $2.00 handling fee. WRITE OR CALL FOR OUR 36 PAGE CATALOG OF OTHER TUBES, PARTS, BOOKS AND SUPPLIES. 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'06 Heath, Leak, Maranrz, Mclntosh, Newcomb, Pedersen, Pilot, SUNNYVALE, CA 94086 RadioCrafrsmen, Scon, and more. $5.00 408·733·6,46 ORDER FORM DON'T FORGETTO ORDER NAM E ______VAC UUM TUBE VA LlEY �� A MUST READ TUBE AUDIO ADDRESS, ______ELECTRONICS h1AGAZINE! IT CITY______STATE __ZIP _ ____ PRICE HAS VINTAGE AJ'lD MODERN N.EASE SEND THE FOLLOWING PRODUCTS! TUBE AUDIO ARTICLES ISSUES) __ USS251YR(4 $, FOREIGN USS35 NO G.CARDS $:- VINTAGE HIFI PRODUCnONS $ E. DUANE AVE STE FREE SHIPPING [NUSA ADD $7.00 PER ITEM FOREIGN (foreign shipping) :_-_-_ 1095 106 , SUNNYVA1.E, $__ _ CA CA RESIDENTS ADD 7.75% STATE SALES TAX (CA TAX) $ 94086 408-733-6146 NO CREDITCARDS - CHECKS OR MONEY ORDERS ONLY TOTAL ORDER $