THE B.A.S. SPEAKER
EDITOR-IN-CHIEF: Michael Riggs COORDINATING EDITOR: Bernard Gregoire 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 THE BOSTON AUDIO SOCIETY P.O. BOX 7 BOSTON, MASSACHUSETTS 02215
VOLUME 5, NUMBER 6 MARCH 1977
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

We have a meal of many courses this month. Fans of British loudspeaker design will enjoy Collins Beagle's account of his search for a good, small loudspeaker and why he chose the KEF Corelli. At the other end of the reproduction chain, our guest speaker for February, Dr. Bruce Meier of Discwasher, introduces a host of interesting new products. Among these are a clip-on tone arm damper and an alternative to Sound Guard. Elsewhere in this issue you'll find first word of Sony's plans to market in the U.S. their PCM audio recording adapter for the Betamax, some impressions of two Sony cassette recorders, and a discouraging word on SAE's Impulse Noise Suppressor. J. J. Thompson reports on the Ariston turntable. Finally two articles close the issue -- a user's report by Collins Beagle on the Audio Research SP-4 and some perspectives on hi-fi specifications from Al Foster. Stay tuned to this station. We have a bundle of good stuff on tap for the next few months, including a preamp input impedance survey, a kit that will allow you to make those impedance measurements yourself, and reviews of a number of low-cost (under $300) receivers, the Audio/ Pulse Model One, the Shure M615AS equalization analyzer and the Dynaco ST-150 power amp in both stock and modified versions.
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. 6 March 1977 OCRed from printed copy - errors possible.

The BAS Speaker

For Sale
*One pair of AR-12 speaker systems; one pair of new AR-7 speaker systems in sealed cartons; one AR-1W speaker system. Call 687-6016. *Grace G-940 (damped) tone arm, $80; latest Supex cartridge, SD 909, $80; Marantz SE -15 electrostatic headphones (including energizer), $65. A. Balgalvis, 193-15B 69th Avenue, Flushing, NY 11365, (212) 454-3205. *Heathkit Modulus system AN-2016, $950 -- digital FM/AM tuner, four-channel preamp and two AA-1506 dual 60 W/ch power amplifiers. Included are optional modules for FM Dolby, CD-4 and SQ. Cost $1250 before assembly. Unit is assembled, aligned and tested. A. Balgalvis, 193-15B 69th Avenue, Flushing, NY 11365, (212) 454-3205. *KLH 9 electrostatic speakers, new condition, $850; ERA turntable, $125; Thorens TD-125 turntable with Grace 707, $265; Son of Ampzilla amp, new, $340; Advent 300 receiver, new, $230; Sansui CD-5 electronic crossover, $25; Electrovoice T-35 tweeter, $15; CTS 15-inch woofers, $25 each; CTS 6-inch midranges, $5 each; Tandberg 6000 tape deck, $225; Phase Linear 400 amp, new $325; Dual 704 with Shure V15-III, $230; Audio Dimensions preamp, $200; Audio Dimensions preamp with Win Labs cartridge, $200; Southwest Tech 215A amp, $60; H speaker system, $450. Gayle Glidewell, 7724 Querida, Dallas, TX 75248, (214) 2394103. *dbx 119, $130; Sony SQD 2020, $150; B&O MMC 6000, $50; Koss 2+2 headphones with case, $45; Realistic DVM, $75; Heath I0-17 3-inch scope, $60; Texas Instruments SR-50 calculator, $25; SR-51A, $45. Everything in good to excellent condition, complete with manuals. All prices include shipping. J. J. Thompson, 281 Warren Avenue, Kenmore, NY 14217. *Quad 33/303, $325; "classic" Sony ST-5000FW; Revox F36 "electric eye" tape recorder (used 30 hours), collector's item. Ross, (519) 945-8486. *Harman/Kardon Citation Twelve, $185 including insurance and shipping via UPS. John Tooley, (302) 684-3443 (home) or (302) 856-5260 (work). *Ampzilla, metered, still in warranty, recently checked out "OK" at Crown clinic, $575; Audio Research SP-3A-1N with all factory mods, Amperex/Telefunken tubes (new), "uniformity checked" at factory, $450 firm; Sony ST-5130 tuner, recently returned from factory check-up and alignment, $195. Ted Macklin, (919) 722-4566. *SAE Mark 17 ten-band stereo equalizer, $225; dbx 117, $100; dbx 119, $100; Sansui cassette deck, $100. All prices open to offer. Mike, (617) 247-0137. *Trevor Lees preamp, professionally wired on new PAS-3X chassis, used for A-B comparisons (4-6 hrs.). Includes Telefunken tubes and Trevor Lees faceplate, asking $275. Brand new Quad 405 dumping amp -- factory sealed carton with warranty, latest production run (11,300 series, asking $315. Please call (408) 625-2433 and ask for Mr. Meyers. *Collector's Item -- Thorens Turntable/Changer CD-43-N, direct-drive, stacks up to 12 records (any size or speed). Will pause up to 13 minutes between records, variable speed control, repeat and reject, manual or automatic. Perfect condition, $150 with base. Also Supex SD-900E, $75. Supex SDT-180 Variable Transformer, $90. Never used, both $150. Vestigal Arm, never connected, $60. (206) 282-0155. *Dahlquist DQ-10's, latest version, mirror-imaged, $625 pr.; Quad FM-3 tuner, $150. Dennis Curley, (617) 658-6568. *Dyna PAS preamp, $60; Dyna PAS preamp with 4 new LUX 12AX7 tubes, $75; 2 Dyna Stereo 70 power amps, $60 each; Sherwood tube stereo tuner, $35; Direct Box (built from plans in Recor ding Engineer/Producer), $10; Biaural microphones (electret condenser, built from plans i Audio), $20; misc. cables and adapters, $10. Stephen Bayle, (617) 547-2836. *Recording Tape (new): Audio Magnetics -- LN reels 1800', $2.85; XHE cassettes -- C90, $2.40, C120, $2.85 (these are excellent C120 cassettes); XHE cartridges -- C90, $2.25; LN cassettes C90, $1.00; LN cartridges -- C45, $1.10, C90, $1.35. Minimum order is 10, can be mixed. If you order a case of the same tape (24 reels, 48 cassettes or cartridges), take 7% off for saving me from repacking. Add shipping: I'll refund the excess. Bob Sellman, 14 Station Ave., Haddon Heights, NJ 08035.

and produced better sound than I had previously heard from them, as the speakers were already five years old when I bought them. (I have since heard of someone else with a pair of KLH speakers whose sonic character began to change after many years. Upon return to the factory, the cloth edges were re-doped, and the speakers once again sounded like new.) So, nothing magical was intended in my letter, only my observation of the importance of utilizing an acoustic suspension woofer as intended in its design. The moral: If you have old AR or KLH speakers with cloth edges, you may restore their original punch by carefully coating them with a diluted mixture of silicone rubber and tolulene. If you have newer speakers with polyurethane or similarly modern skivers, take Roy Allison's sage -- Bob Graham (Massachusetts) advice and leave them alone.

B & W Backtalk

John Puccio is incorrect in stating (in the December issue) that all the B&W speakers use the same tweeter. The one used in the DM-4 and in the DM-2A is, I believe, made by Celestion. The one they put in the DM-6 and in the DM-5 is of their own manufacture and is a fair amount more accurate than the Celestion unit. Also, the DM-6 is much better than the DM-2A. Although they have a similar sound, the DM-6 has better imaging and a better low end and, quite simply, is just a more accurate speaker system. -- David Sherwood (New Jersey) I was somewhat surprised at John Puccio's comments on the B&W loudspeakers in the December Speaker. I also have recently done considerable listening to these speakers, but I've reached some quite different conclusions. My experience is that the DM-6 ($1200/pair) is far superior to the DM-2A ($700/pair) in any characteristic -- clarity, definition, overall smoothness, frequency response, imaging, dispersion, whatever. Indeed, it is really no contest. The naturalness of the DM-6 is uncanny. It's one of the finest speakers I've ever heard. The DM-6 and the DM-2A have no drivers in common. The DM-2A is really an earlier generation. The DM-5 ($300/pair), on the other hand, uses the DM-6 midrange driver as a bass/ midrange unit and also uses the same tweeter as the DM-6. These two speakers therefore sound very much alike through the midrange and high end. The DM-5 is, of course, rather lacking in bass response. But I'd buy a pair of DM-5's before I'd buy DM-2A's, even if the prices were reversed. (A combination of DM-6's and DM-5's would make a very nice four-channel setup.) But anyone who is thinking of spending $1200 for speakers (and has a room to match his bankroll) really should listen to the Snell speaker. This is truly an impressive beast, if you have the room for it. And herein lies a provocative (I think) question. The DM-6 and the Snell are both going to cost the U.S. consumer about $1200 (exclusive of taxes). The Snell is manufactured locally; it costs $1200 locally. The B&W is manufactured in England; it can be bought retail in England (again, exclusive of taxes) for about $600 (at present exchange rates), so half of what you pay locally is going for shipping, import duties, and distributor markup. Question: Is it fair to compare these to each other as $1200 loudspeakers? Or are we comparing a $600 with a $1200 loudspeaker? (The proportions grow even more ridiculous if one makes the comparison in England. Maybe there's some geographic point on earth where it all evens out.) But then I'm told that AR speakers sell well in England, where the reverse situation -- Bob Borden (Massachusetts) obtains. John Puccio says that the B&W DM-2A and DM-6 have the same tweeter. Unless the DM-2A has changed (making it a DM-2B) it uses a Celestion HF 1300 MkII and a Coles 4001G HF array; the DM-6 uses a new B&W dome. And to my ears they don't sound even vaguely similar. The high end of the 6 seems spitty and overemphasizes harmonics, while the 2A seems a little bright. More to the point, this discussion raises the issue of judging speakers in dealer showrooms.

In that situation there are so many unfamiliar variables that making a meaningful assessment is close to impossible. To add fuel to the fire, most dealers (including those who should know better) give hopelessly inadequate demonstrations: no attempt at level matching, correct room placement, or use of decent ancillary equipment. Even when dealers pretend to match levels one is often worse off because he/she is operating under the delusion that levels are matched, when, in truth, nobody really knows. Your December amp review points out this problem rather forcefully by demonstrating the erroneous conclusions one can reach when levels are different. The best suggestion I have is to listen to equipment in a variety of surroundings and to choose on the basis of those qualities which appear consistently. Readers of the Speaker can offer assistance by sharing their comments. -- Thomas Martin (Rhode Island)
UDXL/II Rising; Avilyn Declining?
In late 1975 we found that the TDK type SA (Avilyn) cassette provided a significant performance advantage over the best CrO2 tapes and so was the first ferric-based tape to be better overall than chrome. It had 3 to 4 dB better headroom at low and middle frequencies and concomitantly lower distortion of bass and midrange material at normal recording levels (-10 to 0 VU). Other people also discovered this advantage of course, and during 1976 TDK captured from Maxell the leadership position in premium cassette sales. But late in 1976 Maxell made a comeback by introducing UDXL/II cassettes having the same excellent headroom as SA and claiming a better oxide binder. The significance of the latter is that some batches of SA exhibited substantial oxide shedding, dropouts and print-through. So Maxell UDXL/II has in recent months become the premium cassette of choice. It seemed reasonable to suppose that UDXL/II and SA would remain closely competitive, particularly in view of TDK's recent advertisements of a new production run of SA claimed to be freer of dropouts. (The improved SA is signified by a grid pattern engraved in the plastic cassette shell.) But in the February 1977 issue of Hi-Fi News and Record Review (England), Angus McKenzie reports that TDK has actually lowered the performance of the new SA. The reported reason is that though SA and UDXL/II are chrome-compatible in bias and EQ, they are 3 dB more sensitive than CrO 2 and so require a readjustment of the recorder's "rec-cal" controls for correct Dolby tracking. In many Japanese cassette machines, of course, the rec-cal controls are not user-adjustable, being hidden within the machine. So TDK reportedly has reduced the sensitivity of SA to eliminate the need for readjustment of machines set up for CrO 2. But in so doing they have thrown away the only advantage SA had over chrome! So if McKenzie's report is correct, we are left with the consistently superb Maxell UDXL/II as sole contender for first place, with the better brands of CrO 2 occupying a close second place (and still an attractive alternative as they cost significantly less than Maxell). -- Peter Mitchell (Massachusetts)

Yamaha vs. Advent

I spent about one-half hour at a local dealer's salon comparing the preamp section of the Advent receiver to the preamp section of the Yamaha CA-800. They did not sound similar, and the various differences were not what I expected from reading preamp reports in the Speaker. The Advent had virtually no sibilance on "Sweet Baby James, " from James Taylor's album of the same name. The Yamaha had quite a bit. On Maynard Ferguson's "Give It One, " from MF Horn 2 , the Yamaha had more zzzzz on trumpets, but also noticeably more ambience, particularly on the alto sax solo. The Advent sounded smoother and somewhat less "live." On the basis of the Ferguson, I would have called the Yamaha "excellent, " assuming the trumpet zzzzz to be actually on the disc, and the Advent "good. " But on the Taylor I would have said the Advent was "good" or "excellent," and the Yamaha "edgy." Yamaha's blurb shows a pronounced rise in THD at low input levels to the phono preamp. Perhaps this factor is responsible for the anomalies I heard, and the Holman square wave, white noise and cartridge interaction tests don't define all the obvious audible differences. Associated equipment was the Audio-Technica 11, BIC turntable (I think), the Advent power amp and double Advents. Comments? -- Crawford Best (Louisiana)
The SAE Pop Suppressor: Not What We've Been Waiting For
In the last few weeks I have tried out some new equipment, including the SAE impulse noise suppressor. I obtained a sample from the first shipment of these, with a serial number around 1200. I connected it to my system and played a very static-laden RCA record through it, first using the "invert" mode for calibration, then the "normal" mode for normal operation. The total effect was remarkable. Not a single tick or pop was removed. Only musical peaks were affected, with what sounded like sandpaper being spliced in in place of the transient information on the record. This was true at any setting of the external controls on the unit and for any reasonable signal level in or out of the box, although the degree of garbage contributed by the SAE device could be varied with the primary adjustment lever on the front. Because it seemed to go about its task in a fundamentally lame way, I took the unit back for a replacement. The replacement sample behaved identically. It appears to freeze the signal level for several milliseconds whenever it thinks it sees a click, but you could skip the technical analysis and just listen to any harpsichord recording through the device. Considering the massive advertising campaign it is being given, and the relatively affordable price, it may well poison the reputation of SAE for a long time to come (assuming that the two samples I had were representative). Given that the worst-case behavior of the unit was astoundingly bad, I should hasten to point out that I found no musical material of any nature with which the unit made any discernible i mprovement in the sound without also causing very disturbing side effects. -- David Satz (Massachusetts) According to SAE's advertisements, this new $200 product eliminates "clicks and pops caused by scratches, static and imperfections" on records, "with no adverse effect on the quality of the recorded material." There should be a large market for such an accessory. My recent experience with two of these units, however, was disappointing, particularly in view of the advertising build-up. As I recall the description in the owner's manual, the circuitry detects phase and transient signals characteristic of imperfections such as scratches, momentarily interrupts the signal to eliminate the scratch sound, and, by detecting the musical signals immediately preceding and following the offending signal, recreates the musical portion of the signal eliminated in the pro-

cess. The unit includes a front panel control to adjust the threshold of the detecting circuits. I leave it to members more expert than I to explain the electronic theory underlying the concept. The dealer demonstrated the unit by playing a record with a single, and clearly visible, scratch engraved on the surface with a key. I understand that SAE has been using the same demonstration in persuading their dealers to carry the product. The demonstration is convincing, and I purchased a unit and installed it in my system, as recommended, through the tape monitor circuits. Two fundamental problems became apparent almost immediately and continued over several days of auditioning with various sensitivity settings. First, though the system effectively removes widely spaced scratches, when the record presents the system with the multiple, fairly closely spaced scratches typical of older records, the unit's electronics apparently are unable to recover quickly enough between scratches. Under those circumstances, closely sequenced scratches are reproduced as mild thumps, creating a curious, non-rhythmical accompaniment to the music. Second, when the sensitivity is set high enough to eliminate scratch sounds, the system distorts amplitude peaks to the point of making the recording unlistenable. The circuitry apparently senses the peaks as scratches and tries to eliminate them. Suspecting (hoping) that my unit was defective, I returned it to the dealer for another. new unit exhibited the same problems and was returned to the dealer for a refund. The
I believe that both units were from SAE's early production, and perhaps SAE will resolve the problems in later production samples. I suspect, however, that elimination of the defects will require at least some changes in the electronic design. I would caution prospective purchasers to await a refined product from SAE or from other manufacturers, such as Phase Linear, reputed to be developing systems with a similar purpose. Given my experience with the SAE units, any such product should be purchased under a clear understanding with the dealer that the unit, if unsatisfactory, may be returned for refund. -- Ward Stevenson (Connecticut)

Ariston RD-11S Turntable

The first impression one has of this turntable is that it looks very much like the legendary Linn Sondek LP 12. According to Hi-Fi News this is because Mr. Hamish Robertson was involved in the design of both units. The Ariston is very similar to the Linn in operation and features. The one big difference is that the Ariston offers both 33 rpm and 45 rpm speeds. The RD-11S is very well constructed. The two-piece platter appears to be aluminum and, according to their literature, is precision ground and balanced and weighs 9 1/2 pounds. The unit does not have the usual rubber or composition mat, but rather, two rubber rings inserted in grooves in the platter, so as to support 7-inch or 12-inch records near their edges. The platter and arm are mounted on a subassembly suspended on springs below the main chassis, as in the Linn Sondek. This arrangement seems to give excellent isolation to feedback in my system. The motor is a 24-pole hysteresis motor mounted to the main chassis with rubber dampers to further suppress vibration. The pulley assembly is driven through a slip clutch. This allows the platter to be stopped without having the belt slip, thus preventing damage to the belt. Speeds are changed by removing the outer portion of the platter and moving the drive belt from one pulley to the other, as on the AR turntable. The speeds on my unit appear to be exact. The main bearing is a ball bearing setting on a teflon plate, upon which the main shaft rests. The shaft and bearing assembly appear well machined and are well fitted. There is no sign of play in the bearing assembly of my unit. The manufacturer states that wow and flutter are 0.03% and rumble is -74 dB weighted, although which weighting is not specified.

time I had found a speaker I liked whose price ($185 each) fell between those of two personal favorites for their prices, the large Advents and the Magnepans, so I decided to compare the Corelli's to them. The Advents, in comparison, sounded muffled and veiled, not open in the high end and otherwise inferior. The comparison with the Magnepans was more complex and less conclusive. The Corelli's seemed to have a more neutral tonal balance throughout the frequency range. The Magnepan's hot spot in the lower treble area really stood out by comparison (even though recent Maggies have less of this problem than earlier ones). The Magnepan's rolloff in the extreme highs was evident, giving the Maggies a mute, muffled sound compared to the Corelli's openness. I assume that tonal balance irregularities also account for the fact that female singers sounded almost nasal on the Maggies, while on the Corelli's they seemed more natural and defined. The Magnepans did seem more detailed and perhaps more open in the midrange. Surprisingly to me, there was a greater sense of depth with the Corelli's. Finally, the Corelli's bass response seemed more natural and better defined. My overall conclusion is that the Corelli's tonal balance is its main advantage over the Maggies, though the Maggies are probably capable of providing a more spacious sound and of handling high volumes with less strain. As you perhaps can guess, I was very impressed with the Corelli's, and, after trying them at home for a while, I purchased a pair to serve as a reserve and portable speaker. I was perplexed that KEF seemed to be competing with itself. There was the "Reference Series" of speakers, the 103's, 104's, and, I assume, the 105's. Then there was the "C Series," of which the Corelli is the bottom of the line (the others being the Calinda and the Cantata). And to my ears the Corelli was certainly superior to the 103 and to a lesser degree to the 104. By implication the C Series must be a group of superior performance speakers which should "do in" the Reference Series in the marketplace. Why was KEF doing this? I contacted the KEF rep and was informed that the two series were designed for different markets. The Reference Series is for those who want high volume levels. The C Series is for those who need less volume and want (by implication in the conversation) superior definition and basic performance. The main apparent design difference between at least the 103 and 104 versus the Corelli and the Calinda is in the nature of the B200 midrange/woofer used. The 103 and 104 use the B200/SP1039, which has a large magnet and voice coil (the larger coil permitting higher power levels). The Corelli and Calinda use the B200/SP1022, which has the same large magnet but a smaller voice coil (this is the same driver used by I M Fried in the H's woofer). This seems to result in a more accurate driver with superior definition. (The B200 sold as a separate driver for speaker kit projects is the B200/SP1014, which has a small voice coil and a small magnet.) Whatever else is different, I certainly prefer the C Series. All of the above statements are based on general impressions of all the speakers at the Music Center, Charlottesville, Virginia (a very cordial store whose staff was very obliging in letting me make lengthy comparisons between their products on my own). After I had lived with the Corelli's for a few weeks, I did discover certain limitations in their performance (as I am sure I would have if I had lived with the others). As the KEF representative suggested, the Corelli's are limited in the volumes they can generate; they sound strained if driven above about 90-95 dB, especially with complex orchestral passages. And they generate a more restricted sound field than speakers such as the Dayton Wrights. But they do have extraordinary bass response for their size, being one of the best mid and upper bass speakers with which I am familiar (this is the characteristic that most impresses people who listen to them). As is to be expected, the speakers are sensitive to placement. All of my descriptions have been of the speakers away from the floor and walls. If placed on the floor, the bass becomes bloated, making the midrange seem restricted. If put on book shelves the sound becomes less open and more two-dimensional. They do seem to have a compatibility problem with tube electronics. I took them over to the home of a friend, who has a modified Dyna PAS preamp and a modified Dyna Stereo 70 amp, to compare them to FMI 80's. Though the Corelli's definitely had superior response in the bass region and extreme highs, strange things happened in the midrange and lower treble. A saxophone which had been a full-bodied presence with the 80's became a shadow on the Corelli's. But more surprisingly, the Corelli's took on a silvery quality especially noticeable with female voices. If anything I would have expected the Corelli's to sound dull with tubes. We found the results perplexing. I have tried the Corelli's with various solid state electronics -- Dayton Wright SPL preamp and SAE 2500 amp, Crown IC150A preamp and DC300A amp, Yamaha CA-800 integrated - 1 0-

nivorous" fungi on vinyl. The original Discwasher fluid was intended to reduce such growth, as described here July 1975. Another product, aimed at a related problem and again at the high-line audiophile, is the soon to be released Pro-Disc Environment. This product is outwardly similar to the Ball Brothers Sound Guard, about which Meier has many reservations. Meier agreed with comments in The Speaker of August/September 1976, in which the thickness of the Sound Guard coating was discussed. His product is claimed to be thinner (only one Angstrom, or less than half the thickness of Sound Guard) in addition to possessing a significantly different surface chemistry. The first problem with the Ball Brothers product is its method of application, which Meier compared with pouring paint on a floor and returning hours later to spread it around, hoping for an even coating. The Pro-Disc formulation is not simply an aerosol spray but requires use of the "Environment. " This is a flat rectangular chamber which holds the disc to be treated while a fog is introduced by metered sprays into the four corners of the plastic box. The spray is never directed immediately onto the record. Nozzles to produce a well-dispersed mist required extensive development, as did the chemical formulation. The chemical is designed not only to form a single "mono-molecular-layer" on the record surface (a coating only one molecular diameter thick), but also to produce a thin, soft, adaptive layer of small molecules which will do the intended job -- and all of this without using any toxic material or ozone depleting propellent. Meier claimed in no uncertain terms that the components of Sound Guard did not meet these requirements, particularly with respect to atmospheric contamination. Meier was specific in his chemical terms (claiming that any molecule containing fluorine and chlorine and no hydrogen would be a villain) and claimed that the Freon 112/113 used in Sound Guard was under indictment in Washington. Finding a chemistry for Pro-Disc which does not lead to these problems has caused great delay in releasing the final product. Other problems with the competitor include the method by which the film binds itself to the surface of the disc. In Sound Guard, a vinyl chloride component does the binding, but only after temporarily softening the surface of the disc and "melting" into place after a 15-minute delay recommended by Ball Brothers. Pro-Disc will not possess this flaw and will bind directly to the vinyl. As to the function the coating is to perform, Meier again found room for disagreement. Although both materials do lower the friction between the stylus and the vinyl, this is not important at low (audiophile) tracking forces. More important is (1) the sealing of the surface against contamination, again thinking of those fungi, which grow on organic residue from fingers and from room air; and (2) overcoming a subtle thermal effect. The roughly 16 tons of pressure per square inch beneath the stylus causes tremendous local hearing in the record surface for a distance of 1 to 4 thousandths of an inch below the stylus. The heat dispersing qualities of the Pro-Disc coating reduce this thermal shock, or "trauma," by a factor of four, thus reducing the minimum time between disc playings and cutting down on this form of "wear." Note that friction at the disc is not the problem, and adding lubrication between the stylus and the vinyl in no way reduces heating caused by pressure. The validity of data to the contrary, as printed by Ball Brothers was strongly disputed. The Pro-Disc coating is claimed to be permanent and non-removable either by wear or by chemicals. To prevent accidental re-application, the system "marks" the disc to indicate that the chamber and the chemical have been used. Toxicity data are now being taken prior to public release, and hopefully no further problems with the formula will be found. The cost of the system is to be $24, and replacement sprays (to coat 80 sides) will be $6. Asked about the feasibility of application at the pressing plant, Dr. Meier responded that manufacturers are generally too cheap and that he has no intentions of marketing this product other than to audiophiles. Even his own Cleveland Orchestra direct-to-disc record (see below) will not be treated. Meier also noted that DGG discs, which are fogged with silicone, are not compatible with Pro-Disc. It seemed that the. formula balls up on the surface rather than dispersing properly. Note this if you buy the unit. Throughout his description of the product Meier referred to laboratory data, holograms and electron microscope photographs which he had taken in developing Pro-Disc. Although no data - 1 7-

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Damping at the Shell The final highlight of the evening was the introduction of a really practical add-on tone arm damping accessory, the Disctracker. The device consists of an air piston damper (a dashpot) which is mounted atop the headshell using the cartridge mounting screws. The dashpot consists of a 0.2 inch diameter carbon block which rides within a pyrex cylinder. The sealed base of this cylinder is rounded and, through a cloth pad, contacts the disc surface to the inside of the stylus contact point. The assembly thus resembles an outrigger, with the stylus tip and the damper riding rogether over the disc. A small hole in the carbon piston allows a controlled rate of air leakage from the sealed, bottom portion of the cylinder to the upper, semi-sealed portion. This "dashpot" can move with little resistance at low rates, but if the cylinder is rapidly pushed upward, the resistance to motion is very high. This "velocity dependent" resistance to motion is exactly what is required of a damping mechanism. The degree of damping (the value of "" in the Phoenix article) is determined by the size of the hole. The value for the Disctracker will be fixed at a value chosen to optimize normal lightweight cartridges in normal, low-mass arms. (The value was specified as "1500 dynes-force" at an unspecified velocity, while natural stylus damping was listed as about 250 dynes.) In operation over a warp, the function of the damper is to prevent the stylus from being pushed out of contact with the disc and to eliminate infrasonic output from the cartridge. At the beginning of a warp, in an undamped arm/cartridge combination, the highly compliant (i.e. , easily moved) stylus will be forced towards the body of the cartridge (thus producing a massive output signal), and the arm will, after a time lag, be forced out of contact with the disc. With the damper, however, the dashpot will be stiff at the warp frequencies and force the entire arm to rise with the warp before the stylus has been pushed very far into the cartridge body. The undesired audio output will therefore be low and the arm rather than the stylus will be tracking the record surface. This is exactly what is desired for frequencies below 20 Hz. Further technical discussion is left to a forthcoming tutorial by Meier, to be sent on bingo-card request from the glossies, and to the original Phoenix article. We do note, however, that the device weighs about 1 gram, all of which is right at the end of the arm. But because the infrasonic output is overdamped, the rise at "resonance" is nil and the exact placement of the resonant frequency (if out of the audio range) is relatively unimportant. (See Phoenix's curves for = ~ 1. Meier will be supplying to the BAS a series of laboratory resonance curves both for arms equipped with his device and for a number of high quality arms and cartridges without damping. These will be published when available.) A demonstration with a badly warped disc illustrated well the proper action of the device. With the dashpot attached there was no audible effect from tracking the warp, and visible woofer motion was small. With the Disctracker disabled the arm fully left the groove and the woofer was violently pulsed at the warp. Although the role of damping is most easily described in terms of improved trackability over a warp, the more important effect is cleaner sound in deep-bass passages. Meier claimed to have measured a decrease in low frequency distortion by a factor of 1/2 with the device attached, which is (based on BAS work) fully believable for damped versus undamped tone arms. When the Disctracker is attached to an arm the stylus tracking force should be increased by 0.5 gram with no change in the anti-scating. Life of the cloth pad is at least 1000 hours, and a replacement treatment is included with the original purchase price. The device has even improved the performance of a Dual arm with a decoupling resonator (when used with the heavy Supex cartridge), which illustrates, first, that this arm is not ideally damped (at least for high mass cartridges and, second, that two damping systems may be better than one. The Disctracker also solves some longitudinal resonance problems in extremely weak or thin arms and seems to stabilize the tracking of some cartridges over "horns" left on the disc surface during cutting of the master. It seems that cartridges which use a very short nude diamond can, when they collect gunk off the disc surface, snag on these rough cutting ridges and cause unexpected mistracking. The Disctracker helps stabilize the arm, thus minimizing these problems. Although Meier did not severely attack the Phoenix/Graham system, he did feel that arm damping should be applied as near the stylus as possible, rather than at the end of the arm. Most - 1 9-

likely the major problem with the BAS system is not with its design, but rather with the need for a liquid lubricant in an open container, plus the fact that the device must be made by hand and cannot be purchased. Mathematically, the criticism seems unjustified unless the resonance problem is down the length of the arm rather than in the stylus/arm system. One possible criticism of the Meier product is that, for small defects in the disc (dimples and bumps), the tracker rides over a different portion of the disc than the stylus and cannot respond with perfect accuracy, at least not for both up and down portions of the bump. In light of its small price (less than $30), the ease of mounting on almost any arm, and the probable improvement in bass response over the good surface of a disc, the Disctracker is fully worthy of examination by the BAS when samples become available. Meier closed discussion of the Disctracker with the comment that an international-standard headshell must be designed, and that such a shell with an integral Disctracker is a natural product and will be in the offing at the proper time. Nearly forgotten through the evening was the array of Audioport equipment, which was used for the demonstrations. The system included a pair of Lentek Monitors (KEF woofer and other drivers), STAX DA 80 amplifiers, STAX SRA-12S preamplifier and driver for STAX Earspeakers, the less expensive SRD-7 Earspeakers with energizer, a Luxman turntable equipped with the STAX UA-7 arm and a new "Entre" moving-coil cartridge imported from Japan and used with the Denon transformer. The Entre, at 5.8 grams, is claimed to be the lightest moving coil cartridge on the market and sells for $200. A description will soon be available from the Discwasher Group. A $50-60 head amplifier is also in the works, but no time was specified. Final comments included a new recipe for use of the Zerostat: squeeze in and out at three locations on the disc, then squeeze in at the center and remove the Zerostat from the record before releasing the trigger. Black magic, yes, but this will de-static at least 30,000 sides before the crystal wears out. Neither Meier nor the members in attendance were worn out by the end of the meeting, and another three hours would have been delightful. With his barrage of small but important products, Dr. Meier both entertained and educated his audience, and his presentation was warmly received. - Harry Zwicker

close. Several friends have come over to listen to this comparison, and some (even experienced listeners) have had trouble telling them apart. Those who did detect a difference fairly uniformly felt that the SP-4 was a bit better defined, with perhaps more detail and airiness. Of those who heard this comparison, four of us had heard the original SP-4, and we all agreed that the two SP-4's did differ. This raises questions about the unit-to-unit consistency of production SP-4's. I do not believe that the original SP-4 was measurably faulty, or it would have exhibited greater difficulties. The dealer has been using it as a demonstrator, apparently without problems. One of my friends who listened to this second comparison brought over his stock Lees preamp with both standard Telefunken tubes and special production run Telefunken tubes (friends of his had suggested they were superior to standard tubes). We first hooked up his Trevor Lees with the special tubes to compare it to the SP-4. The Lees had a fat, slightly amorphous sound. The SP-4 had greater depth, much sharper focus, better definition, and was generally cleaner throughout. There was no sense of air about the musical sources with the Lees, as there was with the SP-4. The Lees was fatter in the bass region, with the SP-4 having superior bass definition. My friend's reaction was somewhat different, as he was used to the Lees. He did think the SP-4 had better definition and was cleaner and airier, but he would use the words "full" and "fuller" where I have used "fat" and "fatter." Then he replaced the special Telefunken tubes with the standard ones, and the performance of the Lees improved. The two preamps were much closer, with less pronounced differences in depth and focus, but the Lees was still a bit fat in the bass region, and the SP-4 was still better defined and airier. Again, my friend would find the Lees fuller in general and smoother in the midrange, but he did consider the SP-4 to be better defined and airier. After all I had heard about the Trevor Lees preamp, I was disappointed in its performance. Perhaps the above performance reflects more the ability of my friend to build the unit than the basic performance of the design itself. After all of these comparisons, I feel that the SP-4 is not worth the $895 Audio Research is asking for it. But at least in the case of the second SP-4, because of its very good performance, superb construction and flexibility, I would pay the original price of $695 for it. The SP-4 is not the ultimate, state-of-the-art device described by Audio Research, but it is a very good preamp. Perhaps the biggest effect locally of this series of comparisons has been to increase our appreciation of the job Tom Holman has done in designing the preamp section of the Advent 300. It appears to be a state-of-the-art contender at a very modest price. Postscript : The above sort of subjective review reflects a different point of view than is usually seen in these pages, so I would like to present a statement for a philosophy which I and many others in the audiophile community hold. I would like to suggest that in comparing preamps matters are not as simple as Al Foster's work would suggest (see pp. 1-9 at the end of the June 1976 issue of the Speaker). Though his tests and the data he has supplied provide interesting and useful information on a gross level, I believe there are too many performance parameters and trade-offs involved to make simple divisions into "excellent, good, and edgy" categories. Contrary to what Foster seems to suggest, not all desirable performance characteristics (i.e. , high definition and detailing, openness and airiness, depth, smoothness, etc.) go hand in hand in the same device. In the above comparison the db had excellent definition and detailing but was somewhat two-dimensional and edgy. By reputation, though the Levinson JC-2 is excellent in most respects, it is even more two-dimensional than the db. My friend's modified Trevor Lees seemed the most three-dimensional and least veiled and edgy of the group compared, yet it ranked poorly in terms of definition. Similarly, by reputation the ARC SP-3a-1 has a most three-dimensional midrange, despite its other shortcomings. The first SP-4 had conflicting qualities, with a superbly defined and detailed upper frequency range but a soft midrange. So preamps can differ in terms of performance characteristics, depending on the part of the frequency range to which one is listening. Except for the standard Trevor Lees unit, I would consider all the preamps I compared to be very good units which would probably fall into Al Foster's "excellent" category, yet they all differed. In fact, neither I nor any of my friends (as far as I know) has ever heard two preamps which sounded exactly alike, and we have heard quite a few. Comparing preamps can be further complicated by the differences between the people doing the evaluating, independently of the true sonic differences and similarities between the preamps. First, people's hearing differs. For example, I have a more extended upper frequency hearing -3 a

range than most of my friends, yet I have relatively poor deep bass hearing. This will affect my evaluation of the performance of components. Perhaps relatedly, people also differ in what areas of performance they react to most strongly. Again for example, I react more quickly to mid and upper bass fatness and upper frequency problems than most of my friends, while they react more quickly to midrange problems or edginess. (These differences may also be influenced by the sonic characteristics of the system one lives with.) The above differences in perception combine to affect what aspects of performance one reacts to and the degree to which one reacts to them. So two people listening to two preamps may differ in their responses. One may consider the two units to be about identical while the other considers them to be different, because one person's hearing pattern stresses the area where the preamps differ while the other's de-emphasizes it. Both people have drawn valid subjective conclusions. But even if two people hear the same differences with similar intensity, they still may differ in aesthetics, in the trade-offs they are willing to accept. One person may value high definition over the absence of edginess, while another person might have the opposite inclination. I prefer the SP-4 to the Levinson JC-2, because I value more highly the SP-4's three-dimensionality than the Levinson's bass response. I am sure others would make the opposite choice. So even if we agree on what we hear, we may disagree about the relative merits of the units. Eventually tests which deal with all these factors may be developed -- tests which correlate sufficiently with subjective listening experiences to be decisive -- but until that time the ear has to be the final arbitrator of performance in audio products.
A Publication of The B.A.S. Listening With Your Eyes: Hi-Fi Specifications Alvin Foster It is by now a commonplace to divide audiophiles into two broad categories: those whose primary interest is music and who have little, if any, interest in audio equipment, and those whose interest in such equipment is as intense as their interest in music. What is not generally observed is that members of the former group are usually far more content as audiophiles than are members of the latter. Consider the following contrast between two extreme types: the NonTechnical and the Techno-Freak. The Non-Technical This person is the happier of the two. Often he owns a record player or tape recorder which may be decidedly worse than average. The Non-Technical does not worry about this because the idea that better sound is possible or desirable does not concern him. The Non-Technical has accepted the fact that no assemblage of hi-fi gear recreates a musical experience indistinguishable from the source. He doesn't worry about specifications which might tell him how far he may be from the original. He maintains that the musical experience is personal and private. Why let a fact sheet come between him and Beethoven, anyway? The Techno-Freak This person is more concerned with the specification sheet than with what he hears. He is easily spotted by eager hi-fi salesmen out to make their quotas. The Techno-Freak rarely asks for equipment to be demonstrated: specifications are what is important. This is just fine with the salesman. He doesn't have to go through the tedious tasks of patching line cords or matching playback levels. He simply presents the "fact" sheet, stands back and waits for the fish to take the bait. The salesman is happy with his money, but the Techno-Freak's delight is usually shortlived. Soon after he installs his new gear, he begins to wonder if he purchased wisely. The "letdown blues" set in. The Techno-Freak has accepted the uncomfortable notion that sound is something like a photograph. The picture cannot carry the original scene to the viewer; some features will be de-emphasized, while others will be highlighted. These distortions in the playback of his "musical scene" spoil the listening experience for him. To minimize his anxiety, the Techno-Freak pours over specification sheets. The anxiety returns however, when he notices little, if any, sonic differences between his new "super-spec" unit and his old Zenith. The Techno-Freak's "let-down blues" stem in part from the fact that most hi-fi specification sheets are misleading. Such sheets Iist numerous measurements which often do not correlate with what one actually hears. Hi-Fi Specifications High-fidelity manufacturers have long been involved in the battle of specifications. The amount of data presented to the consumer is often overwhelming and requires the use of expensive, specialized instruments to verify. The arduous testing procedures necessary to arrive at the figures are often long and time consuming. Despite all these technical fireworks, one fact remains: most specifications are of no use in selecting hi-fi equipment. To see why this is so Copyright 1977 Alvin Foster b

we must first look at a basic unit of hi-fi specifications -- the decibel. The Decibel The decibel (dB) has been defined as the smallest change in volume (sound level) the average human ear can detect. Some authorities have gone so far as to claim that only a trained ear can discern a one decibel change. The ability to hear level changes decreases rapidly at low volumes. One can easily hear a level change of 10 dB when listening to music at a comfortable playback level of 75 dB. However, if the music is being produced at 40 dB (background noise level for most homes) and is then lowered to 30 dB, the difference may not be perceptible. Distortion Only two characteristics of distortion are meaningful: type and amplitude. The type, or nature, of the distortion indicates what harmonics or intermodulation products are added to or removed from the program source. This particular delineation of distortion rarely appears on manufacturers' specification sheets. But knowing the nature of the distortion is important because laboratory tests have confirmed that some distortions are inaudible primarily because they are easily masked by the harmonic structure of the music. The second characteristic of distortion is amplitude. The amplitude of the distortion tells us how high the level of the distortion products is relative to the level of fundamental tone. For example, if the fundamental of a horn is 200 Hz it is important to know how much the amplifier is likely to add to the horn's second harmonic, 400 Hz. If the amplifier adds too much to the second harmonic the tone character of the horn will be decidedly altered. Audibility of Distortion The habit of buying specification sheets rather than trusting one's ears has forced its own distortion into the hi-fi market. It has pushed the hi-fi manufacturers into promoting generally meaningless facts and figures in order to peddle their wares. To build amplifiers with ultra-low distortion, manufacturers must spend money your money. THD (total harmonic distortion) figures on the order of.001% (100 dB below audibility) are now obtainable in amplifiers. Is this really necessary when studies published in Stereo Review and in Hitachi's Research Laboratory Journal and other studies (my own included) indicate that harmonic distortion in musical material must be as high as 2-5% before audibility? Couple this with the fact that the lowest IM (intermodulation) distortion I have ever measured on a record at a realistic playback level is 1%. Disc manufacturers in general try not to exceed the industry norm, which, according to the Audio En cyclopedia , is that intermodulation distortion which at 3.5 cm/sec for each channel will not be more than 3.5-4.0% for a groove diameter of 11 inches. As the diameter decreases toward the end of the record, the distortion will rise to about 5-6%. Records are the most popular and least expensive playback medium in the hi-fi community. They also yield the worst distortion figures in the reproduction chain. In the disc playback system the greatest distortion factor is tracing distortion, which is created by the improper angling of the stylus to the surface of the disc. The Techno-Freak believes that the reproduction chain should be distortionless, i.e., less than.001% (-100 dB). Fortunately, even for the TechnoFreaks, this extremely difficult requirement does not have to be satisfied. The background noise level in most homes is the equivalent of about 1% distortion; a typical tape recorder generates the noise equivalent of about.05% distortion. Background noise does an excellent job of masking distortion. (Masking occurs when a sound is so dominated by another as to be inaudible.) Distortion may be inaudible for other reasons: it often blends or mixes well with musical overtones and few musical instruments produce a pure tone output of only one frequency. Most musical sounds are made up of a complex arrangement of sinewaves, or tones, which give an instrument its unique character. Distortion is much more difficult to detect in complex tones than in simple ones. The "Ideal" System The specifications of an ideal system are not easy to state. b -2Most of the listener's tastes and