THE B.A.S. SPEAKER Coordinating Editor: James Brinton THE BOSTON AUDIO SOCIETY Production Manager: Robert Borden P.O. BOX 7 Copy Editor: Joyce Brinton BOSTON, MASSACHUSETTS 02215 Staff: Richard Akell, Stuart Isveck, Lawrence Kaufman, John Schlafer, James Topali, Peter Watters, Harry Zwicker VOLUME 4, NUMBER 10 JULY 1976 THE BOSTON AUDIO SOCIETY DOES NOT ENDORSE OR CRITICIZE PRODUCTS, DEALERS, OR SERVICES. OPINIONS EXPRESSED HEREIN REFLECT THE VIEWS OF THEIR AUTHORS AND ARE FOR THE INFORMATION OF THE MEMBERS. In This Issue This is a usual, run-of-the-mill, jam-packed issue of The BAS Speaker. The feature articles include another contribution from Dan Shanefield, this time on the audibility of phase shift in high- fidelity systems, especially loudspeakers—a hot topic of late, as a number of firms now are touting phase-coherent speaker systems. Shanefield helps us decide whether they are worth the shouting. Speaker designer Roy Cizek explores a topic heretofore somewhat devalued—the size of speaker wire needed for best combined amplifier-speaker performance. This topic has generally been overlooked since some observers decided merely that larger gauge was better, but Roy not only has done the math to show why heavier wire is better, but notes deleterious effects of small gauge wire on other aspects than (the normally referred to) damping factor. You will be surprised at the number of parameters a simple thing like choice of speaker-wire gauge can affect. You may only think you own a 400-watt amplifier.. This month marks the first in a hoped for series of "Sonnets (bad pun) from the Japanese" so to speak, beginning with descriptions of some forthcoming Japanese products and a discourse on one of the better Japanese high-fidelity magazines. There are designs for two "turn-on/off transient eliminators" and information (not good) on the Atlanta low-TIM power amplifier project. Tonearm damping surfaces again as a BAS member takes a bite out of (adoptive fellow member) "Jaws" Rabinow, and the Audio International fiasco seems close to being resolved. And theres more. Read on.. Membership dues are $12 per year (October 1 to September 30) or portion thereof. Dues include a one-year subscription to the BAS Speaker. ( Note that almost the full amount of dues is allocated to production of the Speaker. The local activities of the BAS are strictly self-supporting.) For further information and appli- cation form, write to: The Boston Audio Society, P.O. Box 7, Kenmore Square Station, Boston, Mass. 02215. Copyright 1976 The Boston Audio Society Vol. 4, Num. 10 July 1976 The BAS Speaker OCRed from printed copy - errors possible. Stolen While visiting Boston in June BAS member Desmond Fretz ' suitcase was stolen with his new Audio Pulse Model One inside. Beware of buying a used unit cheap; it may be his stolen one. The serial number of the missing delay line is 01054. For Sale • KLH-9 ' s, 6 panels (3 pairs). In mint condition, recently rebuilt with individually selected and matched tweeters. $1500/pair or best offer. Prefer to sell all three pairs to one buyer. Leave message for Dick Goldwater (617) 492-1364. • Dynaco 400, excellent condition, $285. (617) 749-2219. • Mint (brand new) latest Mark Levinson preamplifier (JC-2) with ML white ash case. (919) 449- 4132. • Revox A77, Mark IV, 1/2-track, high-speed deck, 30 hours use, $800. Gately SM6A mixer, 6 in, 2 out, like new, $350. Pair AKG C451 mikes with N46E power supply, used five times, $500. Desmond Fretz (215) 822-1226, after 6 p.m. Wanted • Dynaco PAS-3X preamplifier or other decent-sounding, modestly priced replacement for my PAT-4. David Temple, 300 South Street, Medfield, Mass. 02052. (617) 359-2915. • Advent 100A Dolby B, any condition, price negotiable. Also dbx 122. Call Ken, (617) 646-3427. Help Wanted (Non-Human) I am trying to get a copy of George Frows book A Guide to Edison Cylinder Phonographs, published by Anthony of St. Austelle, Britain, in 1970 and due for reprint soon. Ive been unable to locate it even at the Edison Historic Site in New Jersey. If anyone knows where I can get a copy, please send me the source and price (if known). — David Weinberg (Maryland) Speaker Mailing The following members have decided to rotate the responsibilities of labeling, stamping, and bagging the newsletter for a particular month. If you are interested in assisting, please contact the appropriate distribution manager. Month Name Community Home Phone July John Ouzts Brookline 738-1035 September Jim Topali Watertown 924-4944 October Carl Covell Somerville 776-3894 August Speaker Due to vacations and the lack of people to fill in, the August Speaker will be combined with the September issue. This dual issue will be approximately double size. More on Audio International As we noted last month, there are two Audio Internationals in Germany. A highly placed source at Audio tells us that because of German federal legal pressure, the questionable Audio International (Berlin) has been forced to write all its customers offering them either a full refund or eventual delivery (in one or two months). This latter option is seen as a bit shaky since A.I. has yet to stock the promised Revoxes. This seems to indicate that A.I. was indeed an attempted fraud, but hopefully the authorities have the situation under control. 2 Boston member Ken Deen, who originally reported on this, has received one of the letters and has requested the refund. Well let you know if he gets it. — Joyce Brinton (Massachusetts) Low-TIM Amplifier Kit Delayed Damon Hill, of Atlantas Audio Forum, writes to let us know that Electronics One is no longer selling the circuit board for the low-TIM amplifier construction project that appeared in the February issue of Audio. This means his attempts to put together a kit of parts will be delayed unless he can find someone to make the boards. Correction on Sony Cable Capacitance Unless Sony has changed since I bought my PS-1800A turntable and tonearm, there is some incorrect data in The BAS Speaker listing indicating that all Sonys have 210 pF lead capacitance. I used a capacitance bridge from both ends of the tonearm cables (with cartridges disconnected, of course) and measured 133 pF left channel and 143 pF right channel—just some more data to cloud the issue. — David Weinberg (Maryland) PCM Again Regarding the PCM article in Audio Amateur (3/75) mentioned on page 10 of the March 1976 issue of The BAS Speaker, I believe your correspondent to be seriously in error about the back- ground noise on the PCM-recorded Odyssey disc Y33200. The audible noise is not due to the recorder, but is studio noise (air-conditioning rumble, etc.). Indeed, I believe that I can even hear some traffic noise in the background. How many records have low enough tape noise for this to be possible? — Stanley Lipshitz (Ontario) Other Audio Societies We have recently become aware of several more audio societies. While we dont have a lot of information about them, here is what we do have: • Saint Louis Audio Society . A new organization. For information write: Saint Louis Audio Society, 7435 Cornell, University City, MO 63130. • Chicago Audio Society . The first meeting of the group took place on June 8th. Thirty responses were received from a newspaper ad in the Chicago Tribune. What was more encourag- ing was that six individuals volunteered to help and have come up with some good ideas. For further information contact: Phil Marrow, 387 N. Edgewood Ave., Lombard, IL 60148. • Melbourne (Australia) Audio Club . This group has been active for about two years and publishes its own monthly newsletter. They have a membership of over 200 and are still growing. The activity of the membership is astounding—between the regular monthly meetings at least nine special interest groups meet and many of these actually listen to music (something too few audio club members ever seem to find time for). — J. and J. Brinton (Massachusetts) The Digital World Approaches The audio world is becoming increasingly digitized. The first indications were gimmicks: digital frequency readouts on FM tuners. Then the Heath AJ1510 tuner came out using digital frequency synthesis for station selection as well as readout. The LED power readouts on the Bose 1801 and Harmon-Kardon Citation 16 power amps are obtained by an analog-to-digital con- version, as are similar pseudo-VU meters available elsewhere. 3 Now we have the Infinity Class D switching amplifier, which has a recognizable signal at the input and at the output, but everything in between is digital. The Audio Pulse and Sound Concepts delay lines are digital signal processors, as are the more advanced professional versions. (The Sound Concepts unit processes analog data digitally; the Audio Pulse converts the analog data to digital before processing.) Why such a profusion of digits? Basically, because there are many tasks that need to inter- face with computers, and many tasks that need greater accuracy than is available on an analog readout. Because of this, the audio world is beginning to use the spinoffs of products originally developed for other purposes. For example, several years back, the military went to pulse code modulation (PCM) for secure, high-rate communication. Infinity uses a similar technique in their amplifier. Digital shift registers are a basic part of any computer, and of much other advanced hardware. These same shift registers are in use as the basic operating technique in audio time-delay units. Onward to Microprocessors . The big new tool in the digital world is the microprocessor.