EL84 - The Baby ·With Bite ~ -3008 lval•atlon \\ \ A Music Lover's Triode \ ) I / / ' \, i l Sweep Tuite OTL Prolect 200 Watt EL509 Amp i I ' t RCA Tulle Manufactur n 1 CUI i§·i il·J• i ,i it-Sil it·) ii ~feu h ninql,,am RArno ~ R d d i d t r o n TIJ!!s Illustration by Ken t Leech EDITOR'S P A G E A ND INDUSTRY N E W S advice to unsuspecting beginners. We also has sets of replacement indicator would advise these "experts" to do some light jewels for $4.25/set of five . VTV Issue# a more research before spreading misin­ The Fisher Doctor Table of Contents: formation. 27 Daleham Street This si tuati on is even worse on Staten Island, NY 10308 rec.audio.tech, rec.audio.high-end (718) 948-7489 ,El84: The Baby with Bite ••••• 3 and alt.guitar.amps. And the World Wide Web with its seemingly millions Counterfeit NOS Tube Boxes Listening to the EL84 •••••••••••• 8 of commercial websites has become the Steve Martin of Antique Electronic -~weep Tube OTL Amp •••••••• 10 ultimate last resort for charlatans and Supply notified us of an individual in rip-off-artists. T here are no controls, Hong Kong who is producing fake :'R~A Tube Manufacturing•••• 15 regulations or second opinions. At least NOS-type tube boxes. The company in wi th newsgroups, anyone spouting crap question is producing boxes with: . Radiotron Handbook••••••••• 18 will be called on it by others. If you Amperex, RCA, Tung-Sol, Telefunken plan on buying anything off the web, be and Mullard brands. The boxes were in ,!adiotron CD-ROM ............. 19 extremely cautious! the miniature nine-pin size and have no ''Inside ENIAC •••••.••••............ 20 cube numbers printed on the box flap. Watch what yo u are buying out there! ·- 300B Evaluation................ 22 Vacuum Tube Enthusiast Weekend and VTV Tube School ~AudioNote Kit One ..•••••••••• 24 On November 8 and 9, 1997 a spe­ .,.lube. Dumpster - 12SX7••••• 25 ;;,'\ cial Tube Enthusiasts Weekend will be held in Tempe, Arizona. The events on _: Bruce Moore lnterview....... 26 the 8th will include two free electronics · .Distortion Analyzers .......... 30 swap meets and open houses at Antique Electronics Supply and Arizona Tube J'JTV Visits AES in Tempe .....32 Audio. Vacuum Tube Valley will pre­ Japanese Tube Group Visits VTV sent Tube School for Audio and Guitar Advertiser Section •.••.•.••••.•• 34 Amplifiers (two separate classes) on the On June 12-14, MJ, the premier 9th with John Arwood, Charlie Japanese audio magazine, sponsored a Kittleson, Evan Aurand and Ritchie tour for 14 tube enthusiasts from Fliegler as instructors. Cost for the Japan. The group along with the edi­ Update: Tubes on the Internet eight hour event is $99 prepaid and tors of MJ visited the VTV office, sev­ $129 at the door. Although the internet is useful and a eral collectors, equipment dealers, sur­ so urce for lots of information, audio plus stores and the Foothill Contact Vacuum Tube Valley for a surfers on the WWW need a reality Electronics Fleamarket in Los Altos, flyer on the event: FAX (650)654- check. Popular news groups such as: CA. Members of the group found 2065, website: www.vacuumtube.com rec.audio.tubes are becoming lots of rube-related goodies, made new "rec. tubes. wanted.and.for.sale. " Recently, friends and had fun. Technical Questions we checked this newsgroup and noted Make Your Fisher Beautiful! VTV appreciates all the interest in that over 50% of the postings were for our journal and vacuum tube electron­ tubes wanted and for sale. In addition, You can now replace those trouble­ ics, however, we are unable ro answer all there are several aggressive "instant some brass Fisher knob caps! Al the telephone inquiries regarding techni­ experts" who are giving out misleading Pugliese, The Fisher Doctor, has excel­ cal questions. Please send yo ur ques­ informati on. Some of these fellows do lent quality reproduction machined and tions via our website email: triode@vac­ not even use their real names! T hese lacquered knob caps in either plain or uumtube.com. You can also FAX or web mongers seem to have lots of time with indicator line for $3.50 each. H e send questions via US mail. on their hands to give spurious Vacuum Tube Valley is published quarter­ Copyright 1997 Vacuum Tube Valley™ lyJor electronic enthusiasts interested in the and Big Tone™ All rights reserved. colorful past, present and future of vacuum Charles Kittleson - Editor and Publisher No part of this publication may be reprinted tube electronics. John Atwood - Technical Editor or otherwise reproduced without written permission of the publisher. Subscription US$32.00/year (4 issues) Eric Barbour - Staff Editor Send circulation and editorial $43/Canada and $63/Asia , $53/Europe Terry Buddingh - Guitar Ed itor correspondence to: Cash, US Bank Check,or Credit Cards Vacuum Tube Valley are accepted for payment Steve Parr - Art Director 1095 E. Duane Ave., Suite 106 Julie P. Werner - Copy Editor Sunnyvale, CA 94086 USA Phone - (408) 733 - 6146 e-mail [email protected] FAX - (650) 654 - 2065 Website - www.vacuumtube.com ISSN # 1095-4805 VACUUM TUBE VALLEY ISSUE 8 E L 8 4 T H E B A B Y W ITH B I T E EL84: The Baby With Bite ~-~ 17WATTS By Eric Barbour PUSH-PULL POWER © 1997 All Rights Reserved at 300V. B+ 9CV with a pair of Intro Like many audio tubes of today, EL84 MINIATURE tubes originated with Philips BV in Eindhoven. It is getting routine to speak of popu­ This highly productive R&D operation lar audio tubes as having little or no his­ could fill up a book with just their better­ tory. Whereas truly innovative tubes such known electron tube developments. All as the 6L6 started an electronic revolu­ from the minds and hands of nameless tion, there are many types which hardly engineers in Holland. This popular 9-pin rated mention--until recently, when they miniature tube was derived from the very became essential to musical sound. The different Rimlock base tube found in development of such popular tubes was most countries where Philips had a pres­ more-or-less accidental, or at least of little ence. importance at the time. History A fine example is our present subject. The small power pentode EL84 is now Just after World War II, much of regarded as a leading guitar tube, and as a northern Europe· was in ruins. classic for high fidelity. Yet it was devel­ Populations were utterly weary of war, oped from an undistinguished series of and now that it was over, they got on audio-output pentodes, used in low­ with their lives. And they started buying power hi-fi, tape recorders and many AC radios again. As a result, more new elec­ powered European radios. One small tronic tubes were introduced in the 1946- · change in the screen grid, to allow its 1950 period than in any other time. Amperex® operation at voltages similar to the plate 1 (300 volts), made a low-cost radio tube The tube manufacturers were well­ ELB41 &BQS into a high-fidelity audio device. acquainted with the new glass-base minia­ ture tubes from the USA, first introduced LOW-DISTORTION, by RCA in 1939-1941, and it was obvi­ HIGH-GAIN POWER PENTODE ous that the future was in miniature • True pentode characteristics for low types. So, starting in 1947 with the distortion and high peak power. British MOY Z77 pentode, a rush of • High gain and sensitivity resulting types appeared. Known as B7Gs in in reduced driver stage distortion. • 12 watts plate dissipation in a Britain, they were usually identical to miniature envelope. American types already existing. • At 300 volts, capable of 17 watts at 4% distortion (without feedback) Except, that is, for a new line. in Class AB push-pull pairs. Produced by Mullard and Mazda, later by • 5.7 watts output at 10% harmonic distortion (without feedback) Philips (Mullard's owner) and as a single-ended output stage. Telefunken, the Rimlock series of tubes were essentially like 9-pin miniatures, except that their bases had 8 pins. And OTHER Amperex TUBES FOR early examples were equipped with a large HIGH-FIDELITY AUDIO APPLICATIONS: metal ring on the base, with an alignment 6CA7/EL34 High.power penfode; 100 WPP pin to allow use in twist-and-lock sockets. EF86/6267 low-noise high-µ. pentode The appearance was like a small Loktal ECC81/12AT7 Low -n oi.se medium-µ dlXII triode base, minus the center locating bung. A ECC82/12AU7 low-noise low-µ dual triode ECC83/12AX7 low.noise high-µ dual rriode major introduction in the Rimlock types ECC85/6AQ8 High -µ dual triode for FM tuners was the Mullard/Philips UL41, one of the GZ34/5AR4 Cathode-type rectifier; 250 mo. first audio output pentodes with a minia­ EZ80/6V4 9-pin rectifier; cathode; 90 mo . ture base and the precursor of an entire EZ81 /&CA4 9-pin rectifier; cathode; 150 ma. family. At All leading Electronic Par,s Distr"butors The UL41 was intended for 100-mA series heater strings in AC-DC radios and Amperex ~ televisions. It led directly to the EL41, Bugle-Boy ELECTRONIC CORP. identical except for the more convention­ 230 Duffy Ave ., Hicksv ,lle, Long Island, N.Y. EL84 al 6.3v heater. The EL41 begat the EL8 l , VACUUM TUBE -VALLEY ISSUE 8 E L 8 4 T H E B A B Y W ITH B I T E which bore a newfangled 9-pin miniature base in the American style.