Fits Nikon D40, D40X, D60 Fits Nikon Coolpix S200, S500, S200, S510, S700, 5600 Fits Nikon Coolpix S550 Fits Nikon Coolpix S610 Fits Sharp VL-A10E, A111 Fits Sharp VL-A10E, A111 Fits Sharp PD3, PD6, WD 250E, WD 650E, VL-MEIOE Fits Sharp MC500, MC100 Fits Sharp Z1, Z3, Z5, Z7, Z950, Z800, Z500, Z300, Z100, VL2, VL25, VL27 Fits Sharp PD3, PD6, WD 250E, WD 650E, VL-MEIOE Fits Sharp PD3, PD6, WD 250E, WD 650E, VL-MEIOE Fits All old Panasonic, Sony, JVC (old camcorder) Ni-CD Fits All old Panasonic, Sony, JVC (old camcorder) Ni-CD Fits Panasonic FX1, FX5 Fits Panasonic FZ1, FZ10, FZ20, FZ3, FZ5 Fits Panasonic FZ30, FZ7, FZ50, FZ18 Fits Panasonic, JVC (old 8mm camcorder) Ni-CD Fits Panasonic GS400, 250, MX500, Hitachi DVD, 730, 750, 780, GX20E, GS250, 75, 150, 400 Fits Panasonic GS200, 250, 75, 150, 400, 320, 230, 85, 60, MX500, Hitachi DVD, 730, 750, 780, GX20E, H250, H21, H20, D310, D220, D160 Fits Panasonic GS200, 250, 75, 150, 400, 320, 230, 85, 60, MX500, Hitachi DVD, 730, 750, 780, GX20E, H250, H21, H20, D310, D220, D160 Fits All Panasonic DS65, DS60, DS65, MX500, Hitachi DVD, GS11, GS15, MD9000EN Fits All Panasonic DS65, DS60, DS65, MX500, Hitachi DVD, GS11, GS15, MD9000EN Fits All Panasonic - NV-R210 EN, NV-V210 EN, NV-VZ1, NV-V230 EN, NV-V570 EN, NV-V550 EN, LC-1 Fits Panasonic F7, FZ-1, F1 Fits Panasonic AV100 Fits Panasonic FX8, FX9, LX1, FX01, FX50, FX70, FX3, LX2, FX12, Fuji F40, SDR-S7 Fits Panasonic TZ1, T1, T2, T3, TZ11, TZ15 Fits Panasonic Lumix DMC-FX30 Fits Panasonic S100, S300, S150 Fits Lumix FX30, FX21, FX33, FX69, FX55. FX520, FS3, FS5 Fits SDR-H60, SDR-H40 Fits HDC-HS9, HDC-SD9, SDR-H280, VDR-D310, VDR-D50 Fits JVC P3, P7, P9, P75, P300 Fits JVC P3, P7, P9, P75, P300 Fits JVC 507, 707, 960, 96, 76 Fits JVC D50, D70, D90, 300, 500, 4000, 5000, D53, 33, 73, 93 Fits JVC D50, D70, D90, 300, 500, 4000, 5000, D53, 33, 73 Fits JVC 70, 80, 90, 48, 78 Fits JVC 70, 80, 90, 48, 78
Rp480,000 Rp380,000 Rp420,000 Rp550,000 Rp430,000 Rp430,000 Rp550,000 Rp550,000 Rp550,000 Rp580,000 Rp580,000 Rp650,000 Rp350,000 Rp480,000 Rp400,000 Rp400,000 Rp480,000 Rp500,000 Rp580,000 Rp480,000 Rp500,000 Rp600,000 Rp550,000 Rp750,000 Rp650,000 Rp650,000 Rp550,000 Rp450,000 Rp480,000 Rp350,000 Rp530,000 Rp480,000 Rp430,000 Rp580,000 Rp650,000 Rp450,000 Rp480,000 Rp500,000 Rp550,000 Rp600,000 Rp630,000 Rp630,000 Rp630,000
JVC SDV BN-VM200U JVC SDV BN-707U JVC SDV BN-714U JVC SDV BN-808 JVC SDV BN-815 JVC SDV BN-VF815U wireless (NEW) JVC SDV BN-VF823U (NEW) Sony SDV NP-BD1 Sony SDV NP-BG1 Sony SDV T1 Sony SDV FR1 Sony SDV FE1 Sony SDV FC-11 (FC-10) Sony SDV FS-11 Sony SDV FS-21 Sony SDV FM55H Sony SDV SQ-50 Sony SDV SQ-70 Sony SDV SQ-91 Sony SDV NP-FP70 Sony SDV NP-FP90 Sony SDV FH50 Sony SDV FH70

THE B.A.S. SPEAKER

EDITOR-IN-CHIEF: Michael Riggs COORDINATING EDITOR: Henry Belot STAFF: Henry Belot, Robert Borden, Joyce Brinton, Dana Craig, Frank Farlow, Robert Graham, Lawrence Kaufman, James Lindquist, Peter Mitchell, John Schlafer, Jack Stevens, James Topali, Peter Watters PUBLISHER: James Brinton, President, BAS VOLUME 5, NUMBER 4 JANUARY 1977 THE BOSTON AUDIO SOCIETY P.O. BOX 7 BOSTON, MASSACHUSETTS 02215
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 month's issue features an audiophile's whirlwind tour of (audio) Wonderland -- Japan. Peter Mitchell doesn't report seeing any white rabbits with watches or smiling cats, but he has seen such amazing sights as the Yamaha factory (one of them, anyway), a PCM audio recorder for consumers , and a new approach to ambience recovery that does not involve: (a) matrixing, (b) high-frequency whistles, (c) extra amplifiers, or (d) extra speakers in your listening room) The feature articles this time around are, straight from the horse's mouth, the details on AR's computer digital delay system and from John Puccio a statistical look at the truth dispensed by the golden ears. We also bring you follow-up reports on Mike Riggs' modified PAT-5 (impressive specs) and Bob Graham's treatment for acoustic suspension speakers (too much of a good thing?). Al Foster hooks up his test gear to a recent Sheffield record and likes what he sees as much as what he hears. Plus our customary collection of reader comments, classifieds, and periodical highlights. After you've read this issue you should feel informed, entertained, and inspired to send us your contributions for forthcoming issues. We say it elsewhere, but it's worth getting it in here at the front as well: our mailbox has been nearly empty of late, so if anything in this issue clicks a responsive chord, and something should, let us know. That way the next issue will be bigger and better. -- Henry G. Belot (Massachusetts)
Membership dues are $14 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 application form, write to: The Boston Audio Society, P.O. Box 7, Kenmore Square Station, Boston, Mass. 02215.
Copyright 1977 The Boston Audio Society
Vol. 5, Num. 4 January 1977 OCRed from printed copy - errors possible.

The BAS Speaker

For Sale
*Advent 100A Dolby outboard, low-noise power supply, walnut case, $175. EPI 100 loudspeakers, walnut cabinets, still in warranty, $125/pr. Dual 1218 turntable with Shure V15II cartridge, $99 or best offer. Peter Bronk, (617) 734-9057. *dbx 124 in factory-sealed carton, never used, $212. For information, call Dave evenings or weekends, (617) 729-5173. *AR receiver, just back from factory service, $200 or best offer. Two SWTPC Universal Tiger amps (stereo pair) mounted in a single, custom walnut cabinet, output transistors mounted on extra-massive heat sinks, $100 or best offer. Call Ken at (617) 646-3427. *B&W DM-70's (walnut), $800 for the pair, packing included. Sony TC-153SD with case and battery pack, like new, $275. Tandberg 9241XD, best offer. Two pairs of JBL-100's, $600. Bob Heenan, 1906 Beacon Street, Brookline, MA 02146, (617) 731-0140. *One pair AR 3A's in very good condition in original cartons, $225. Denny Boyer, (617) 483-8734. *One-year-old Dyna FM-5, aligned locally -- right on. Good price. Harry Brawley, Cambridge, MA, (617) 491-7210. *Philips 202 turntable with Stanton 681EE and Audio-Technica AT-11 cartridges and two extra cartridge clips, $90. Bob Borden, (617) 276-3417, days. *Two Sony CRS-3N anti-shock microphone mounts, for most cylindrical microphones of around one-inch diameter. Come with spare elastic and extra rubber fittings for use with smaller or larger diameter mikes. $40/pr. David Satz, (617) 492-2263. *Highest quality sound at a very reasonable price: Marantz 8b classic tube amp in mint condition, $200; DB Systems electronic crossover prototype for stereo biamp or for triamp, with two selectable monitoring meters, level controls, and adjustable subsonic filtering, with power supply, $150; Harmon-Kardon Citation 12 classic transistor amp in good condition, $175. Wayne Robertson, (617) 648-4191 after 6:00.

Wanted

*Marantz 9's, JBL SE400's or 460, Marantz 7 or JBL SG520. Bob Heenan, 1906 Beacon Street, Brookline, MA 02146, (617) 731-0140. *I am seeking to buy or trade for an ARC D-76a amplifier. Wayne Robertson, (617) 648-4191 after 6:00.

Setting the (Biggs) Record Straight
I would like to correct a bit of misinformation contained in the November 1976 issue of the Speaker. In the Meeting Notes of the October 24th meeting, Al Southwick reported that "special two-record sets of E. Power Biggs at the Methuen organ were available at the [Methuen Memorial Music] Hall, autographed by Mr. Biggs." In reality, the Board of Trustees offers for sale, at its sponsored concerts at the Hall or by mail order, the Columbia album (one record) M34129, Stars and Stripes Forever , autographed by the artist E. Power Biggs. Albums at the Hall are priced at $6.99 each; mail order copies are $7.49 each. Many of the selections were recorded on the 1863 Walcker Boston Music Hall Organ now in the Methuen Memorial Music Hall. It is an SQ recording and was produced by Andrew Kaz -- Edward J. Sampson, Jr., Vice President, Methuen Memorial Music Hall, Inc., Methuen, din. Massachusetts

Richmond Audio Society

A few audio-minded engineers in Richmond, Virginia have formed the Richmond Audio Society. We plan to have monthly meetings with discussions of topics of interest and occasional guest lecturers. Our first meeting, in November, featured a talk by Harold Beveridge and a demonstration of his electrostatic speakers. Anyone interested in taking part should contact Roger Modjeski, -- Collins Beagle (Virginia) 2215 East Broad Street, Richmond, VA 23223, (804) 782-9736. -3-
Sheffield Produces a Winner
Sheffield's recent direct-to-master-disc recording, "The King James Version" (LAB 3), brings back a respected member of the big band tradition, Harry James, and a respected recording technique -- real stereo. Producers Lincoln Mayorga and Doug Sax abandoned their 32 -channel (multiple mono) recording console and settled on a single AKG C-24 stereo microphone. The results are excellent. Lab-3 has none of the phony ambience and close-miked sound of Lab-2, "I've Got the Music in Me." Instead it captures the sound of the band as heard in the natural acoustics of the recording hall (a church). This natural sound helps make Lab-3 a real winner. Like Lab-1, Lab-3 captures a wider dynamic range than Lab-2, i. e. , a greater peak-to-rms ratio. This ratio, expressed in dB, compares the maximum transient to the corresponding "0" VU recording level, and the highest ratio occurs in "Sweet Georgia Brown," one of my favorite cuts on the album. Incidentally, the peak-to-rms ratio can't be measured with an rms meter (e. g. , AC-VTVM) because such meters are not fast enough and average out any instantaneous transient levels. To get good readings of these electrical peak levels, one needs an instrument capable of responding to signals of a few tens of microseconds duration -- an oscilloscope or specially designed peak reading meter. The extremely high peak-to-average range found on Lab-1 and Lab-3 means two things. First, Sheffield has indeed produced a disc with superb high-level transients, and they've done it without decreasing the average signal-to-noise ratio. In other words, the average cutting level hasn't simply been reduced. Second, if one were to play back both Lab-2 and Lab-3 at the same average level in his listening room, Lab-3 might require about twice as much amplifier power as Lab-2 to prevent clipping. And this danger of clipping applies to all the other stages of the audio chain. By the way, the January 1977 issue of Audio tells the Sheffield story and includes an excellent description of the Harry James recording. If you like the big band sound, you will love "The King James Version. " Bargain-priced copies. Local BAS members will be able to buy a copy for $8 at the January 19th meeting. Out-of-state members can get one by forwarding $8.75 to the Boston Audio Society, P.O. Box 7, Boston, MA 02215. I expect the BAS supply will be exhausted by the end of February, so orders received after February will be returned. -- Alvin Foster (Massachusetts)

The More Compleat Acoustic Suspension
In November, Bob Graham described how he coated the edge suspension of an AR-1 with a silicone rubber solution to improve its air seal. Before treatment, the cone took three seconds to return from a fully depressed position; after coating, it took nearly seven. Since November two knowledgeable readers, Tom Tyson and Roy Allison, have shed light on the effects of this treatment and have sounded a cautionary note to experimenters. Here's what they say: Tom Tyson (North Carolina). Bob Graham's article contains an interesting point concerning the seal of acoustic suspension loudspeakers, specifically, the importance of carefully sealing the enclosure and the speaker itself. That Cizek has taken extra care to design his speakers in this fashion is noteworthy, and this should contribute to low distortion if other design parameters are in line. Top quality acoustic suspension speakers, such as the Allisons and ARs, are indeed acoustically sealed, but not pneumatically sealed. That is, the speaker system is airtight with respect to audio frequencies and can maintain air pressure different from atmospheric pressure long enough to cover one-half cycle of the lowest frequency to be reproduced. To the degree that the pressure can be held for several seconds, the safety margin is very large. But if the speaker were pneumatically sealed, the cone would act as an aneroid barometer.
The "classic" AR-1W is now over twenty-two years old in its earliest form. After years of operation the butyl-impregnated cloth skiver oxidizes and becomes somewhat brittle. Air begins to seep through the cloth, and the acoustic seal suffers, with resultantly higher harmonic distortion. A "fix, " as suggested by Graham, is to coat the skiver with a silicone rubber compound, but an easier and possibly better treatment is to apply an anti-oxidation compound, such as ArmorAll GT-10. This material with the ludicrous name is well known to automotive types for its restorative qualities when applied to rubber, leather or vinyl, and when applied to the AR-1W skiver (at least three treatments), the material becomes more compliant and airtight, as originally intended. Contrary to Graham's remarks, a badly-leaking AR-1W would actually have a lower system resonance, in that a leaking skiver reduces the acoustic resistance on the back of the cone. (Remember, the airtight properties of the system raise the free-air resonance of the AR-1W from 19 Hz to the system resonance of 43 Hz.) Restoring the air seal merely brings the resonance back to the proper frequency. Though it is true that, as Graham suggests, the Q would increase if the "springiness" of the suspension were increased by improving the air seal, reducing mechanical resistance in relation to mass reactance at resonance, the Q would not be raised to some higher-than-normal value for a properly-working AR-1W. Nor would a higher Q be desirable: a decrease in damping with the higher Q yields a rise in output in the region of resonance. And though speakers are damped mechanically, acoustically and magnetically, the bulk of damping in the AR-1W comes from the last. So, in effect, correcting a leaking skiver on the AR-1W doesn't turn the woofer into something magical, but restores the original quality of that remarkably fine loudspeaker. Roy Allison (Massachusetts). Bob Graham's suggestion for improving the air seal in acoustic suspension systems should be followed with great caution. First, a perfect (hermetic) seal is not advisable; in fact, it would be disastrous if achieved. A slow "leak" is necessary to maintain equal air pressure inside and outside the enclosure. If this were not provided, normal changes in atmospheric pressure would force the cone to assume a static position inward or outward of its design center. At the least, the speaker would then operate in a nonlinear fashion. At worst, it could be damaged easily by a low-frequency music signal. A seven-second recovery time indicates the presence of a leak still large enough, obviously, to accommodate even rapid atmospheric pressure changes. But one should not aim for a completely tight seal. Second, a coat of gunk on the cone or edge suspension will certainly change the frequency response, especially at high frequencies. The change may be for the better -- perhaps it was in Bob's case -- and that may be why he found an improvement in the sound of his AR-1W's. In most cases, the response will be degraded. Gunk is cheap. If the speaker's performance could have been improved by another coat of such treatment, it is reasonable to believe that the manufacturer would have applied it himself. How much of a seal is necessary? While returning to its rest position after being pushed in, the cone travels one quarter of a complete cycle. If this recovery time is 3 seconds, the system is "leaking" at the rate of 1/12 Hz. At a frequency greater than ten times this "leak" frequency -- say, at 1 Hz or higher -- the system can for all practical purposes be considered to be sealed. A leak that small can have no significant effect on the system's performance down to 1 Hz and no measurable nor audible effect on the system's Q. It is not possible. If you fully depress the woofer cone of an acoustic suspension system, and it takes 1 1/2 seconds or more to return to its rest position, the seal is perfectly adequate. Don't worry about it, and apply gunk to the cone or suspension only if you like to take bets against very long odds.

Comments on the Modified PAT-5
From Jensens I have a few comments about your review (October 1976 Speaker ) of our modified version of the Dyna PAT-5. First, the preamp does not pass DC. All inputs and the unity-gain stage are still capacitively coupled. Only the output circuit is direct-coupled, and no DC can reach it. The reason we warn against use of this unit with amplifiers having direct-coupled inputs is that the preamp does have a very slight DC offset at the output, which could cause problems with those few amps which are not capacitively coupled at their inputs. Second, the 1.5 dB difference in channel balance you note must be caused by volume pot mistracking. All gain is set with 1% tolerance, metal-film resistors, and the two halves should be very close. Finally, just changing phono transistors and capacitors will not give the same performance, and an LM-301 IC is not a good device for audio amplification. We are not surprised that you hear a slight additional "fuzz" in the sound with the tone controls switched in. That's because the output changes from our circuit back to the original Dyna output circuit. We believe our circuit is better, and the fact that you hear a difference confirms this. It does appear, by the way, that Underground Audio is trying to copy our work, but the IC they describe is nowhere close to the performance of the hybrid we use. -- Frank Van Alstine (Minnesota) From Dynaco Aside from some of the wording in your first paragraph (wow! -- are we really that bad'), there are some specific points worth noting. For some time PAT-5s have been supplied with the Siemens transistors in the phono stage, and, as I recall, we even suggested them to Frank (Van Alstine). However, there have been times when they were not available. We really are not sure all that extra capacitance in the power supply makes any listenable difference but would like to hear from those who exercise the control of making one change at a time and then doing extensive listening. Also, there is an implication in the "just takes the pots out of the [tone control] circuit" statement that the job is not being done completely. We disagree. Though we have always been advocates of using the simplest circuit that does the job, I think it is necessary to establish the importance of each of these changes independently. The impedance of the circuit is so low that the treble control circuitry does not have any loading effect. We short across the entire bass control, rather than separately either side of the slider, because we can see no justification for the added switch complexity. Your comment about now being able to hear when the tone controls (set flat) are switched in, where you didn't hear any change before the modification, is interesting. The question is: was the design better before, or does the change elicit more differences? We question that the preamp will now pass DC. I believe there are still some capacitors at the beginning of the high level board, even in Frank's variations. Removing the output coupling capacitor is not something we think is practical in any commercial design, because of the potential for damage to equipment downstream. And I understand that the output impedance at that stage has been changed again from the two ohms you indicate. We are now using (and have been for some time) the Microsystems ICs and have used those by Signetics. These two brands have been found to have the best and most consistent sonic characteristics. Some other brands we have used apparently account for the variability on this score, though I don't recommend that anyone go to the trouble of changing them unless he has some reason to doubt their sonic accuracy. When tantalum capacitors are installed per Van Alstine, some of our people slightly prefer the Signetics, but they choose the Microsystems normally. You make a justified criticism of the high-pass filter, but I don't believe there is a good one in any preamp, so here it looks as though you are singling us out. Finally, if any of you have a PAT-5 that doesn't sound as good as something else, I'll send you a "case package" of the ICs and transistors, and then let's have your (collective) comments. I find it hard to believe that Dyna comes off as badly competitively as some BAS comments would have me believe. -- Bob Tucker (Pennsylvania)

Periodicals: Good News and Bad
Euro-Disc Gazzette Ed Dell, editor and publisher of The Audio Amateur , is going into competition with Brian Leeming by providing a similar record-buying service. His new bimonthly newsletter, Euro-Disc Gazzette , will offer for sale to subscribers European and British imports the editors judge to be of superior musical and technical quality. Included will be reprints of reviews from The Gramophone and Hi-Fi News & Record Review. All prices will include postage, and all orders received before the deadline announced in the newsletter will be delivered no later than four weeks after that date. Subscriptions are available at $2 a year from: Euro-Disc Gazzette, Attn: Jim Callihan, P.O. Box 337, Peterborough, NH 03458. Leach Amplifier Newsletter Those building the Marshall Leach low-TIM amplifier may want to receive Damon Hill's aperiodic newsletter on the subject. The information in the first issue certainly appears useful. To get on the mailing list, write Hill at 3261 Circle Oak Drive NW, Atlanta, GA 30339. Hill asks for, but does not demand, a 25 to 50 cent donation to cover his costs. "Audio-File" Obit Member William Vincent of Connecticut informs us that Audio-File will not, for the present, be published. Editor Brian Sessions has been seriously ill and therefore unable to do the necessary work. Audio-File will return money advanced for subscriptions when requested. We extend to Mr. Sessions our regards and our hopes for his swift recovery.

In the Literature

The Absolute Sound, Volume 2, Number 8, Summer-Fall 1976 *In the first issue since May, Harry Pearson (editor and publisher) announces that he has quit the staff of Newsday in order to publish TAS on its (quarterly) schedule as he had originally intended. Well, we have heard that sort of thing before. Let's hope that in his new full-time duties he can clean up the magazine's (peculiar) fascination with parentheses [(!)]. (They enclose everything from single adjectives to complete paragraphs.) It is (really) frustrating to read articles punctuated (like this). TAS deserves a footnote (or a parenthetical reference) in a sequel to Edwin Newman's Strictly Speaking. *This is quite a large issue, with over 120 pages. *Components in Review: the Audio Research system, Thaedra preamp, Sonus Blue phono cartridge, and the Koss and Acoustat electrostatic speakers. (p. 355) *Considerations: Stax DA-300 and SAE 2500 amplifiers; Gale, Avid 103, and STR Omega II and Theta III loudspeakers; Grace 707 and Formula 4 tone arms; ADC cartridge; and DB Systems preamp. (p. 383) *Capsules: Denon transformer; Micro-Seiki LC-40, B&O 3000, Micro Acoustics 2002, Shure V-15 IIIG , Fidelity Research Mk. II, and EMT phono cartridges; Quatre, DEF 104, and KLH Model 9 loudspeakers; Luxman CL-35 Mk III, Dayton Wright SPS, Levinson JC-1 ac, Dayton Wright 535, and Epicure Model 4 preamps; Technics SL-120 turntable; Citation 16 and CM Labs 912 amplifiers; and the Zerostat. (p. 403) *Further thoughts on the Rabco ST-7. (p. 414) *Sneak previews on Sound Guard and Dayton Wright SPL Mk II-B preamp. (p. 414) *Saul Marantz on modifying the Model 7 preamp. (p. 424) *Reader advice on modifying the Marantz Model 9. (p. 426) *Test reports on the M&K and Shreve modifications to the Rabco SL-8E, the Crown VFW-2 crossover, and the Heathkit 10-4510 dual-trace scope. (p. 427) *The Weakest Link: Room Acoustics. (p. 439) *An index for issues 1-7 is included on a separate sheet. - 8-

The Gramophone, October 1976 *Reviews of the Monitor Audio MA3 II loudspeaker, of the Shure M24H phono cartridge, of the Strathern BTM4 turntable, and of the Hadcock GH228 Super damped unipivot tone arm and its associated lifting device. Hi-Fi News & Record Review, November 1976 *November sees a report on the Harrogate audio fair and an article on loudspeaker sensitivity, plus part two of the compander construction article begun in October. *The best is Bernard Keefe's attack on modern recording techniques, or, as he puts it, "fizzed-up music." He makes a strong argument for returning to the good old days of two-mike stereo. *Also: A comparative review of the Harrison S-200, Technics SU-8600, Luxman L-80V, and JVC JA -S8 amplifiers; a review of the Nakamichi 600 cassette deck, 610 preamp, and 620 power amp; and a review of the improved KMAL M9BA Mk. III tone arm. High Fidelity, January 1977 *Test reports on the Luxman T-110 tuner, Spectro Acoustics 202 power amp, Supex SD-900/E Super phono cartridge, Nikko 7075 receiver, and Levinson JC-1 DC pre-preamp. (p. 37) *Several articles commemorating the 100th anniversary of the "talking machine." Physics Today, November 1976 *Teaching the Physics of High Fidelity: A three-page letter from four professors at Southern Illinois University, Carbondale, IL, discusses a "physics" course which stresses the mechanical and electrical processes of high fidelity. A "lab manual" is offered for $5. (p. 9) * Physics Today is easily found in any physics library, or can be obtained from almost any physicist, or optical or acoustical engineer. Popular Electronics, January 1977 *Stereo Scene column is on various loudspeakers and phono cartridges. (p. 22) *Test reports on Sansui TU-9900 tuner, Kenwood 600 integrated amp, and JVC JR-S300 receiver. (p. 26) *Chemicals for Electronics Servicing: A useful article on various general purpose lubricants, cleaners, etc. (p. 44) *Build a Low-Distortion Low-Cost Audio Generator: Simple circuit claims 0.02% distortion, uses five 741 op amps, and may also be used as a gyrator. (p. 59) *Multimeters for Electronics, Part I: Focuses on traditional VOM's. (p. 61) *Handy Circuit for Checking Phono Preamps and FM Tuners: Circuit uses two 747 dual op amps to provide pre-emphasis networks. (p. 71) Radio-Electronics, January 1977 *Looking Ahead column notes that Henry Kloss has left Advent. (p. 4) *Equipment report on Heath AS-1344 column speaker kit. (p. 26) *TV Games, Part II: More on what's available. (p. 39) *Analog Voltmeters: By Heath engineer. (p. 46) *How Noise Is Measured in Hi-Fi: Len Feldman explains signal-to-noise measurements. Once again, the photos off the spectrum analyzer are fascinating. (p. 49) *Test reports by Feldman on Sony STR-6800SD receiver, Yamaha B-2 amplifier. (p. 56) Recording Engineer/Producer, October 1976 *A thick issue beginning with a good letter on time delay. (p. 8) *A short discussion of studio monitor loudspeakers. (p. 51) *A quite long, very basic, and rather good discussion of the magnetic tape recording process. (pp. 61-68) *And, of course, ads and equipment to make technologists drool. - 1 0-

Meeting Notes Unsounded

The December meeting was a change of pace from meetings of the recent past. Peter Mitchell presented an audiophile's travelog of Japan. We would have liked to have printed some of Peter's slides in these pages, but that being beyond our budget, Peter has adapted his presentation into the feature article which begins on the next page. And so, no meeting notes. I will record two items from the Open Forum. First, there is a plentiful lack of volunteers for the refreshments team. Without volunteers, no refreshments. Each volunteer does duty only once a year (if we have volunteers), so c'mon. We repeat: no volunteers, no refreshments. Second, the Box 7 mail box has run nearly dry. What with the holidays over, there's no further reason to put off those Speaker articles and contributions you have burning inside you. Get ' them off your minds and into our mail box. It will help if you type your item, but you don t have ' to be a literary giant. If need be we ll clean up your grammar and make you sound real good. -- Ed.

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December BAS Meeting
A Tour of the Japan Audio Fair (Ed. Note: The travelogue referred to on page one is scheduled to appear next month.) The 25th Japan Audio Fair occurred under a large geodesic dome in Tokyo October 22-28. Crowds of tens of thousands of Japanese audiophiles, plus hi-fi writers from around the world, attended the 80 exhibits to see and hear the newest audio products. Of course some of the exhibits were operated by importers showing familiar American and European equipment, and some exhibitors were showing products intended only for domestic Japanese sale with no plans for export to the USA. So the most interesting exhibits were those of the major Japanese manufacturers with international markets, where the visitors could see the new products which will be marketed in the USA during the coming year. Many of these products will be introduced in the USA at the Consumer Electronics Show in Chicago in June. In general the exhibits were substantially larger than those at an American hi-fi show; some were elaborate multi-room displays. For instance the Yamaha exhibit consisted of a large winding display area showing off the entire Yamaha product line, plus a fully enclosed sound room seating 20 or 30 people where live performances of pop music alternated with recordings, plus a "hands-on" exhibit. The latter contained several Yamaha tuners receiving a broadcast of the music occurring in the sound room, with each tuner connected to a Yamaha cassette deck and headphones, permitting the passerby to conquer his fear of the equipment by tuning the tuner, making a recording, playing it back, and then going into the sound room to hear the original sound. Evidently the next major fad in turntables will be "quartz lock" direct drive, involving a quartz-crystal controlled oscillator and servo-control circuits to lock the rotational frequency of the turntable onto the exact 33 1/3 rpm rate. Nearly every major manufacturer at the Japan Audio Fair showed prototypes of such turntables. The audible benefit of this tight control of turntable speed is slight but not entirely negligible, since the servo control can eliminate the slight slowing of rotation that may occur with conventional platter drives due to the friction of the stylus in the groove and the pressure of a Dust Bug. Nearly every manufacturer also showed an increased variety of cassette decks, adding to the already bewildering assortment of models on the market. In general the new cassette decks offer no significant improvement in performance compared to present machines, but they do offer the consumer a greater assortment of convenience features and gadgets. An exception to this generalization is the Aiwa AD-7800, a three-head front-loading cassette deck with two unique features, one modestly useful and the second long overdue. (1) Each of its recording level meters has two needles instead of the usual one -- a green needle indicating conventional "VU" levels and a red needle registering peak signal levels on an extended-range 40 dB scale. The peak-reading function is the more useful one for the serious recordist, of course, but it is entertaining to watch the differing behavior of the "peak" and "rms" pointers. (2) Aiwa has done something which cassette decks makers should have done long ago: provided the user with built-in facilities for optimizing the recording bias to obtain flat frequency response with any cassette. With most cassette machines you have to take the recorder to a service shop and trust the technician to do a careful job of adjusting the bias for flattest high-frequency response with the particular cassette tape that you want to use. The Aiwa AD-7800 makes it easy for you to finetune the bias yourself, as carefully as you want, for each cassette that you put in the machine. The recorder contains the necessary 400 Hz and 8000 Hz test tones, metering circuitry, and bias fine-adjust controls (in addition to the usual front-panel bias and equalization switching for selecting tape oxide type). The AD-7800 may appear in the USA next fall under the Meriton brand name. It retails in Japan for $370, so by the usual rule of thumb its retail price in the USA should be around $550-$600. (In general, mass-produced Japanese hi-fi products have a retail price 50 percent higher in the USA than in Japan. On small-market specialized products such as tone arms and moving-coil cartridges the markup by the importer is higher.) Whither Elcaset. The Elcaset, the large-size 3 3/4 ips cassette, is a new tape medium which some market analysts think will be a total flop. It is advertised as providing open-reel performance - 1 3-

to quote an availability date or a price for the audio/digital adapter, but reasonable estimates are two years and $2000. Of course you wouldn't buy a digital tape recorder just to copy records and most FM broadcasts, since these sounds have already been subjected to the aberrations of conventional tape recording. The real value of a digital recorder is to record live sound. In addition to its professional studio gear, Denon makes an extensive line of consumer audio products (receivers, turntables, phono pickups, etc., most of which are not exported to the USA). Their most interesting new product is the Phono Crosstalk Canceller (PCC), available as an outboard accessory box and also built-into the new Denon amplifiers. The motivation behind PCC is the fact that in the real world few phono cartridges exhibit the stereo separation that they are capable of. Nearly-inevitable alignment errors of a few degrees when a pickup is installed in a tone arm, plus similar alignment errors in the factory assembly of the pickup itself, combine to cause the generating elements in the cartridge to be slightly mis -matched with respect to the 45-degree modulation axes of the record groove. Consequently a left-channel modulation will stimulate a small amount of right-channel crosstalk, and vice-versa; a pickup which is capable of 30 to 40 dB of stereo separation then exhibits only 15 to 20 dB of separation in a typical set-up. So the Denon PCC contains phase-inversion and variable -crossfeed circuits to cancel out the crosstalk signals and restore all the separation that the pickup is inherently capable of. A built-in null test circuit permits the user easily to adjust the cross-feed circuits to optimize the system. Denon has made no change in its famous moving-coil cartridge lineup, but the competition in that field is becoming stiffer. For example Onlife Research showed the Dynavector 20 pickup, designed in the Denon tradition with modest compliance and a fairly heavy cartridge body (10 grams), but with so high an output level (2 mV at 5 cm/sec) that no "head amp" or transformer is needed to bring the signal up to normal phono levels. Curiously, the cartridge is offered in two versions; you may choose either a tapered aluminum cantilever or a straight beryllium cantilever, and the choice affects the high-frequency sound of the pickup. Even more interesting is the Dynavector DV505 tone arm, a separated-pivot design like the lamented Transcriptors. The part of the arm which pivots laterally is quite heavy while the part of the arm which pivots vertically has very low effective mass (with the pivot located about an inch behind the cartridge), yielding good tracking of warped records. The mass of the main arm causes a very low-frequency lateral resonance which is attacked by two means. (1) A spring bob weight is mounted inside the arm, with its mass and spring-constant calculated to resonate precisely out-of-phase with the arm itself, thus cancelling the main resonance and splitting it into two subsidiary resonances. (2) These are then damped magnetically. According to the brochure, "A curved rod attached to the rear of the arm is embedded in a magnetic field supplied by two permanent magnets. Any minute movement of the rod, due to an undamped arm resonance, causes an eddy current to be induced in the rod, which in turn interacts with the magnetic field to return the system to its rest state. This highly effective damping also makes the arm impervious to acoustic feedback." It all sounds quite tempting. Incidentally, Dynavector also makes high-grade tube amplifiers, including a preamp for $1200 and a 50 watts/channel power amp for $900. But as far as I know Dynavector products are not scheduled to be marketed in the USA. Ortofon of Denmark introduced their new top-of-the-line moving-coil cartridge, the MC-20, at the Japan Audio Fair. To step up its signal level Ortofon has finally given up on the transformer and has produced a "head amp", the MCA -76 having an effective sub-sonic filter and a low input noise level (better than -146 dBV, i.e. 60 dB below the standard 0.05 mV moving-coil reference level). Speaking of record-playing equipment, perhaps the ultimate toy for the A/B comparison enthusiast is the Micro/Seiki DDX-1000 turntable with mounting points for three tone arms. Teac is importing it into the USA. Tuning Out the Pilot. Two new Yamaha products seemed especially noteworthy. One is the CT-1000 tuner, a modestly-priced version of the classic CT-7000 supertuner (which costs $1200). The CT-1000 has a quoted signal-to-noise ratio of 80 dB in mono and 75 dB in stereo, retains the ultra-low distortion and excellent automatic fine tuning of the CT-7000, and contains one of those clever design ideas that seem so obvious (after you've heard it) that it is hard to understand why it hasn't been done before. In all ordinary FM tuners the pilot filter, used to suppress the 19 kHz stereo pilot, produces high-frequency phase shift and makes it impractical to maintain flat re- 1 5-

sponse to 15 kHz; typically the response of most tuners starts to roll off at 13 kHz and is several decibels down at 15 kHz. However most current stereo tuners employ a phase-locked-loop (PLL) multiplex stereo decoder circuit which contains an oscillator which is precisely locked onto the broadcast pilot tone in both frequency and phase. So Yamaha has simply taken that PLL oscillator tone, inverted it in phase, and mixed it into the audio signal to cancel out the 19 kHz pilot! No pilot filter is needed, and Yamaha can guarantee the frequency response of the CT-1000 to be flat within 0.5 dB to 15 kHz. (Beyond 18 kHz a filter does cut in to eliminate the 38 kHz stereo subcarrier and other ultrasonic garbage.) The retail price of the CT-1000 tuner in Japan is only $200, so its price in the USA probably will be in the $300-$350 ballpark. Incidentally, 1 understand that Pioneer also plans to bring out a tuner employing a similar method of cancelling the 19 kHz pilot without need of a filter. Yamaha also introduced a successor to their CA-1000 integrated amplifier, dubbed the CA1000 Mark HI. Like its predecessor it can be operated either in conventional push-pull Class B (delivering about 120 watts/channel) or in ultra-low-distortion Class A (rated at about 20 watts/ channel). The amplifier has two features of special interest. One is the inclusion of the same "head amp" for moving-coil low-output cartridges that is supplied in their C-2 preamp. The specified input noise level of the preamp, with shorted input terminals, is an amazingly low -156 dBV (i.e. 70 dB below the standard 0.05 mV rating level). Actually it won't be quite that quiet with a real cartridge attached; for instance with an Ortofon MC-20, whose rated impedance is 2.5 ohms, the theoretical minimum noise limit is -152 dBV, still very low. The other feature that I liked in the CA-1000 is its provision of two input selector switches, one which selects what you will listen to and another (labelled REC OUT) which selects the signal which will be fed to your tape recorder, thus making it very convenient for instance to tape an FM broadcast while listening to records or vice-versa. And the REC OUT control has an OFF position which disconnects the TAPE OUT jacks from the amplifier circuitry, ensuring that the input impedance of the tape recorder (or other device connected in the tape-monitor loop) cannot affect the quality of the signal that you are listening to. Inevitably Pioneer expanded their already mammoth product line. Among the new products shown were an attractive and flexible three-way electronic crossover for bi-amping and tri-amping; a low-profile preamplifier modeled after the Yamaha C-2 (which, of course, was itself modeled after the Mark Levinson preamp); a $300 front-load cassette deck with a built-in digital clock and controls to start the recorder at precisely settable times; and the RT-701, an openreel recorder which addresses my pet gripe about open-reel tape decks. In most open-reel decks the heavy motors are situated near the top of the machine and the electronic circuitry is isolated below the transport mechanism, with the result that the normal tape deck is tall, shallow, topheavy (thus easy to tip over), and impossible to stack with other audio components. Pioneer's RT-701 is constructed as an open-reel version of a front-load cassette deck: the 7-inch reels occupy much of the front-panel area with the meters and controls artfully arrayed between and around the reels. The unit has the same proportions as a large amplifier or receiver 19 inches wide, only 9 inches high, and 14 inches deep, so it stacks neatly with the rest of one's stereo components. It is a three-head three-motor machine with a direct-drive capstan, a variable pitch control for playing off-speed tapes, and a claimed frequency response of 20 to 28,000 Hz at 7 1/2 ips and 20 to 20,000 Hz at 3 3/4 ips! The price in Japan is only $380. Evidently the experience of developing and promoting the CD-4 system of four-channel records convinced the Japan Victor Corporation of the importance of reproducing the "sound of space" in one's living room, for JVC has jumped into binaural sound with both feet (both ears?). The JVC exhibit was dominated by a display promoting JVC's binaural demonstration record and cassette, with about a dozen headphone stations set up so that visitors could sample the delights of binaural reproduction. (The content of JVC's demo disc is similar to that of Stereo Review's.) " Binaural Processing." The sonic shock of the Japan Audio Fair was inside the JVC exhibit. A very ordinary-looking stereo system was set up -- cassette deck, stereo amplifier, two speakers, plus an extra box called a "binaural processor." When the cassette was played I was stunned to hear around me the acoustics of a chapel with a choir singing antiphonal hymns. This was not four-channel sound; I checked, and it was clear that the only speakers in the room were the pair on the table in front of me. But I could clearly identify sounds located to the sides and above, including the reflections of the choral sound off the walls and ceiling of the recorded chapel! It has previously been shown that such a super-stereo effect is possible; it has been reported by Dr. - 1 6-

Manfred IL Schroeder of Bell Labs in New Jersey in his research on the perception of stereophonic sound and auditorium acoustics. But the experience of hearing it is stunning. The quoted price of the binaural processor is only $140 in Japan, so it could appear here for about $200, though JVC has not stated whether it will in fact be marketed in the USA. With such a device to free binaural sound from the prison of headphones, record companies could seriously consider issuing binaural recordings commercially -- which would be a valuable departure from the unnaturally-detailed, multiple-microphone recording practices which are common today. Speaking of four-channel sound, one of the fascinating things about the Japan Audio Fair was the virtual absence of quad. It has been reported that quadriphonic sound had been a much larger success in Japan than in the USA, but it seems unlikely. Among the eighty or more exhibitors I could find only one promoting quad: the elaborate Sansui display which, aside from showing assorted QS gear, seemed to be devoted mainly to demonstrating how well Sansui's speaker designers have succeeded in making their speakers sound like JBLs. Another product category which was conspicuously absent from the Audio Fair was time-delay equipment for re-creating in a living room the spacious acoustics of the concert hall; its absence was unexpected in view of the favorable publicity that time-delay has received in the USA and England. And it is all the more surprising when we recall that Matsushita, the parent company of Technics and Panasonic, makes the analog bucket brigade IC which has been widely accepted in the USA as an effective way to produce audio time delay. The other proven way to produce an audio delay system is via digital signal conversion, and both Denon and Sony have shown themselves to be adept enough with digital circuitry to handle that task. Their response to my inquiries about the absence of time-delay units at the show left me with the impression that the costly four-channel bust has made the major Japanese manufacturers more conservative and less sure of their ability to create a market for a new kind of product. (Note that tentative approach that many are taking toward the Elcaset.) Technics had actually developed a time-delay unit, and demonstrated prototypes at an engineering convention last year, but they decided to shelve it until they become convinced that people are ready to buy time delay. (Or maybe they only want to undertake one gamble at a time, and right now they are trying to get the Elcaset off the ground.) So it will be up to American designers (Audio/Pulse, Sound Concepts, and others) to lead the way with timedelay. This review of the Japan Audio Fair is only a survey of highlights -- and a personal survey at that; another audiophile would doubtless have found different innovations worth noting. But it is clear that we have many pleasures to look forward to as these products begin to appear in our local stores during the coming year. Nor can we, any more, regard the Japanese designers as a race of copycats. If it was ever true that the Japanese manufacturers bought their way into the hi-fi world by making imitative products at budget prices through cheap labor, it is no longer true. The major Japanese manufacturers such as Pioneer, Sony, and Yamaha lead the rest of the world in audio component manufacturing because many of their products are better-designed, bettermade, more rigorously quality-controlled, better-sounding, and simply more pleasurable to use than most of the products made elsewhere. And the evidence of the Japan Audio Fair is that they are working to retain their leadership position in the best way possible: by designing new products which are even better than those we see now. -- Peter W. Mitchell

when analyzing the interaction between direct and reflected radiation. By extending the model, multiple reflections may be taken into account. Just as a room made of mirrors would look like an infinite lattice, a reverberant room of rectangular shape can be modeled as a lattice with rectangular cells. Each cell of the lattice contains a source, which emits its sound at the same time as the real source; however, because the distances from the images in the lattice to the listener are greater than that between the listener and the real source, sound from the images reaches the listener after that from the real source. Techniques for analysis of rooms of arbitrary shape, as well as of rectangular rooms, have been developed. The basic program requests from the user the dimensions of the room, the location of the source, the location of the listener, the absorption coefficients of each of the six inner surfaces of the room, and the time period for which reflections are to be computed. Numerous subroutines permit information of special interest to be extracted. The program operates in one of the two following ways when used with the delay network. Method 1. The hemisphere above the listener is divided into sixteen sectors. The delay time, attenuation, elevation, and azimuth of each reflection is computed, and it is assigned to the sector from which it would emanate in a real hall. A graphic and a printed output appear. The graphic output consists of sixteen impulse response charts, representing the complete set of delayed arrivals at the listener's location during the time period under consideration. The patterns which appear offer an indication of the geometry of the image distribution. A printed output provides, for each sector, the time of arrival of the first reflection from that sector and the integrated energy arriving from that sector during a selected time period. Method 2. Another technique maps the reflections in the forward or rear domain, indicating true elevation and azimuth of each image and its approxi mate arrival time and amplitude. 5. The Programmed Delay Network
The system used to present listeners with delay patterns is a sixteen-channel digital time-delay system, designed to reproduce the salient features of early reflection patterns in halls and other direct/delay configurations of interest. Music recordings used with the system contain reverberant decay, so that this component of reverberation does not need to be simulated by the system. The presence of so many delays automatically results in considerable incoherence, as well, so that only the early reflection pattern needs to be controlled precisely, to produce a wide range of effects. The number of channels was chosen on a simple basis. Ten- and twelve-channel analog simulators have been built by others and described as quite effective. The number sixteen is larger than these numbers, comes readily from the digital designer's mind, and is of convenient size to assemble in a reasonable time, so this was the number of channels first chosen for trial. The basic structure of the system was shaped by the use of random-access-memory

Fig. 1 Block diagram

Fig. 2 Signal path
Memory, and 8192-word by 12-bit array of 96 1024-bit random-access memory ICs. Each of the 8192 word locations in the memory is uniquely specified by a 13-bit, binary-coded Signal Memory Address word received from the control section of the network. After each input storage (Write) operation, there occur sixteen Recall operations, corresponding to the sixteen outputs. Each of sixteen successive Recall words read out of Signal Memory is reconverted to an analog voltage sample by the main D/A converter (Datel DAC-MI) and, during the conversion process, is effectively multiplied by a stored preset gain coefficient recalled from the control section. The sixteen analog samples appearing in sequence at the D/A converter output are routed via the Demultiplexer (RCA CD4067) to sixteen output de-emphasis networks, buffer/filter stages, and program-controlled low-pass filters. Channel selection in the Demultiplexer is controlled by the five-bit, binary-coded Slot Word, which specifies one of sixteen recall operations and one write operation. The output filters simulate the high-frequency absorption effects of long air paths, and their response characteristics are set automatically according to the programmed value of time delay. In practice, the fidelity of the isgnal path is comparable to that of a high quality FM transmission, with a slightly higher level of signal-dependent noise. System performance would be marginal for direct reproduction of music, but it is entirely adequate for use as a simulator of early reflection patterns. It appears that the Haas (precedence) effect and high-frequency rolloff at the output of the delayed channels make the perceived noise and distortion levels of the simulation depend only on the quality of the signal from the front (unprocessed) stereo loudspeakers. 8. Control Section
A crystal-controlled clock signal at 544 kHz is divided by 17 in the Slot Word counter to obtain the audio sampling frequency of 32 kHz. The counter's five-bit output, called the Slot Word, is sent to the output Demultiplexer, and to the Program Memory to recall delay and gain values. At the beginning of each 17-step Write/Recall cycle, the Write Address counter is advanced by one count. The 13-bit, parallel output of this counter is used directly to address the Signal Memory during the next write operation, and, during the next sixteen recall operations, is summed arithmetically with each of sixteen Recall Offset words sent in sequence from Program Memory. If the Write Address counter counts upward with time, then a negative number, or offset, added to the counter's output, will address a location lower in memory or earlier in time. The value of this offset is entered into Program Memory through a keyboard, but it could be derived from any analog-to-digital conversion mechanism. Each of the sixteen Program Memory readout operations also produces a Gain Word, which is sent to the output D/A converter to adjust conversion gain independently for each recall operation. Program values are stored in CMOS 256 x 4-bit read/write memory ICs with battery

power backup. If the need were to arise for standardized simulation programs, pin compatible pre-programmed read only memories (PROMS) could be substituted. 9. Interface
The Interface section controls entry and display of program parameters and selection of stored programs. Five commands control all operation modes of the delay network. Two of these, Program and Output, represent destination/source addresses for two data input/output commands, Delay and Gain. The fifth command, Enter, causes execution of commands. To set output 13 of program 7 to a delay time of 23 milliseconds with gain of 0.47, the entry sequence is: PROG, 7, ENT TAP, 1, 3, ENT DELAY, 2, 3, ENT GAIN, 4, 7, ENT Interrogation of Program Memory to determine stored values of gain and delay is performed in the same sequence, with ENT commands omitted after DELAY and GAIN commands. The network described is the subject of several patent applications.
The Boston Audio Society does not endorse or criticize products, dealers, or services. Opinions expressed herein reflect the view of their author and are for the information of the members. A Publication of the BAS Reviewing the Reviewers: A Comparison in Subjective Listening John J. Puccio The following is a bit of summer diddling: a chart of how the so-called "subjective" reviewers are reviewing the same products. It says not so much about the products as it does about the reviewers. It may make interesting reading. Reviewers considered were J. Gordon Holt of The Stereophile , Harry Pearson of The Absolute Sound, Patrick H. Donleycott, John W. Cooledge, and Frank Richards of The Absolute Sound (listed as Others"), J. Peter Moncrieff of Sound Advice , Issue I, and Edward S. Wodenjak of Sound Advice , Issue II. Reviews include full reviews, short reports, recommendations, capsules, quickies, further thoughts, comparisons and brief comments in passing. Where the same reviewer has published several reviews of the same product, only the last opinion is considered. Furthermore, products were limited only to those reviewed by two or more reviewers. And, in fairness to Sound Advice and to maintain interest in current products, reviews were limited to those published in the last two to three years and to those products still in current production. The comparisons themselves are, of course, subjective too, insofar as they are based on my own personal interpretations of a reviewer's comments. (In this regard, trust me, or this whole exercise loses interest already.) Products are listed in descending 'order according to composite average scores. Now, about the scoring: 5 - an excellent product; highly recommended. 4 - a very good product; recommended. 3 - a fair product; possible, conditional recommendation. 2 - a poor product; not generally recommended. 1 - a really bad product; not recommended at all. So here is how I see the various reviewers rating each product. An asterisk (*) will indicate a product about which there is a considerable difference of opinion: perhaps being a sign of differing testing methods, different listening techniques or different biases among the reviewers; perhaps, too, being an indication of a variability in sample to sample product quality. Stereophile Holt Preamps: Levinson JC-2 ARC SP-3A-1* Soundcraftsmen PE2217 Citation 11 Marantz 3300 Marantz 3600 Dyna PAT-5* Phase Linear 4000 Tuners: Sequerra 1 Copyright 1976 John J. Puccio 5