Analog Miscellany: A Roundup of Not Necessarily Related Equipment [Issue No. 12]

A Roundup of Not Necessarily Related Equipment

Preamplifier: Boulder MS (temporary follow-up); Preamplifier: Citation 25 ; Video Projection Monitor: Harman/Kardon VPM 600; Loudspeaker System: KEF Model 107 ; Record & CD Cleaning Machine: Nitty Gritty Hybrid ; Phono Transducer: Win FET-10 (follow-up)

We have a number of different categories here with only one or two items in each, so we are sparing you our usual educational overviews.

The KEF speaker review is, nonetheless, a bit of an education. We were hoping to get as many speakers together for this issue as we did for the last one, but they did not arrive in time and will now have to stay on deck until we can test them. So, instead of another speaker survey, we bring you this potpourri of analog goodies, including our first video equipment review.

Preamplifier

Boulder MS (temporary follow-up)

Boulder Amplifiers, a division of Silver Lake Research, 4850 Sterling Drive, Boulder, CO 80301. MS11 Phonograph Preamplifier, MS21 Selector Switch, MS32 Output Controller, MSO! Power Supply, $3144.00 the system. Tested samples on loan from manufacturer.

We finally received the MS11 module with the active MC pre-preamp option, but not in time to allow us to test it for a complete review in this issue, which of course would have to include a meaningful comparison against the earlier version with transformer input. Boulder products appear to be scarce-probably because they are in demand among professionals and the company is fairly small-and review samples are slow to materialize but invariably worth the wait. This is beautiful equipment, and the price is merely steep without breaking through the high-end cuckoo barrier.

The immediate reason for this brief follow-up is that we have started to use the balanced outputs on the MS32 to drive the balanced inputs of a pair of Boulder 500 power amps (see Issue No. 10) bridged for mono operation. We have always had a philosophical aversion to the use of the ground as a signal return path; it is a primitive solution which goes back to the stone age of audio but has somehow gained respectability in a slow and haphazard historical process un-resisted even by the high end. We therefore hail the new trend to include the option of balanced-line inter connection in audio equipment above a certain price level (such as the Denon DAP-5500 reviewed in Issue No. 11) and want you to know how much we enjoy using the full Boulder system in this mode.

The ultimate luxury in equipment of this sort is to have nothing bad, or even mildly anxiety-producing, ever happen-no hum, hiss, clicks, pops, crackles or other unmannerly noises, no RFI (unless introduced by the phono source) or other interference of any kind, no devices suddenly going intermittent, no ground loops appearing out of nowhere-and the Boulder components operate with exactly such reassuring un-eventfulness. Some of the credit for all that has to go to the balanced-output-to-balanced input connection because it maximizes common-mode rejection and gives the signal complete independence from the ground reference. That, at least, is the theory. In practice, you cannot switch quickly between the unbalanced and balanced modes, so you have to make up your mind about audible differences from (ugh!) memory. We did, and voted enthusiastically for the extra clean balanced mode. We now have long balanced lines between the MS32 and the 500s, and just a few feet of wire between each 500 and the loud speaker. (Almost any kind of wire will do, freaks, when the leads are that short.) Of course, the bridged mono operation of the 500's may have something to do with our enthusiasm. More about that in the article on reference systems.

Preamplifier

Citation 25

Harman/Kardon Incorporated, a Harman International Company, 240 Crossways Park West, Woodbury, Long Island, NY 11797. Citation 25 Remote Control Preamplifier, $849.00. Tested sample on loan from manufacturer.

Remote control has become a way of life in more viewing/listening rooms than we would ever have imagined. Not having to get up from the couch or armchair is a very small selling point to your Editor, who is a compulsive pacer and ne'er-sit-still. Occasionally it is convenient to be able to control the volume, muting, etc., from a distance, and TV channel browsing by remote control is of course the quintessential expression of late-twentieth-century ennui, but to the serious audiophile who likes to fuss with all the controls and adjustments, front and rear, all the time, the ability to command the basic functions by infrared beam is not all that exciting. In this particular case, what we have is a preamplifier quite obviously addressed to those who put a high priority on remote control, but at the same time it is a great deal more than that.

We do not hesitate to call the Citation 25 the most complete and most versatile control center for a residential audio/video system we have ever laid hands on. Up to nine components may be connected to it, selected for sound and picture via the front panel or remotely, and manipulated in just about every conceivable manner. It would be difficult to put together a home entertainment system, no matter how complex, that could not be plugged into it in its entirety, without any additional junctions, selectors, switches, etc., and controlled as a single centralized network. If that is what you are looking for, we can tell you that the Citation 25 does it all, in spades, and you can stop reading right here. If you are a purist looking for the cleanest possible signal path, read on and decide for yourself.

The basic "architecture" of the preamp is very similar to that of the Citation 21, and all the good things we said about the latter in Issue No. 11 could be repeated here almost verbatim. We say almost, instead of exactly, because the signal routing in a remote-control design is of necessity more convoluted and therefore not quite as "pure" as the best solution obtainable in a directly controlled unit. Thus the 25 cannot possibly be superior to the 21 in signal-path quality; it has to be slightly inferior; but surprisingly the difference is very slight, indicating excellent engineering.

When we inserted the entire preamp, from line-level input to main output, into the tape loop of our reference system and switched from the source to the tape loop at matched levels, the added veiling and diminished openness were quite perceptible, more so than in the case of the 21, but far from disturbing. Remember, there is no more brutal test for transparency than this A vs. A+B comparison.

Another small difference between the 21 and the 25 is in RIAA equalization accuracy. The 21 astonished us with its 0.0 dB error; the 25 has a 0.2 dB saddle in the lower midrange of its preemphasized/equalized response. A very minor quibble, but it makes us wonder whether the same highly touted active/passive equalization circuitry is used in the 25 as in the 21 (we have no schematics). On the other hand, the 25 offers a variable input capacitance trimmer for MM cartridges and a variable load resistance trimmer for MC cartridges, both highly desirable and missing from the 21. The trimmers have four positions each, with values we would have chosen a little differently, but that again is a relatively small matter. So is the fact, this time on the credit side, that there is no polarity inversion from phono input to main output.

Cosmetically, the Citation 25 matches the restrained style of the other models in the line, black with tiny white lettering and tiny green LED's. The less frequently used controls are concealed under a flip-down panel; these are not duplicated on the hand-held remote control.

We want to make sure that by characterizing the exact niche this rather special preamplifier fits into we have not disparaged it in the eyes of the serious audiophile. Let us state for the record, therefore, that if no other preamp were available to us, the Citation 25 would keep us quite happy with its sound quality and of course more than happy with its switching and control facilities. It is definitely a winner in its own specific class, and its price is not excessive.

Video Projection Monitor

Harman/Kardon VPM 600

Harman/Kardon Incorporated, a Harman International Company, 240 Crossways Park West, Woodbury, Long Island, NY 11797. VPM 600 Video Projection Monitor, $5990.00. Tested sample on loan from manufacturer.

Sound without sight looks to us like an obsolescent basis for a home entertainment center. There is no doubt in our mind that domestic multimedia installations-complete with big screens, surround sound, digital processors, and other high-tech goodies-are the wave of the future, and the real estate people had better start talking about media rooms instead of family rooms and finished basements. The future is already here in a small way and in scattered instances; the time is not far away when just plain stereo, without video and signal processing, will be as rare as mono is today.

We do not believe that such a trend is necessarily at the expense of music (the boob tube triumphant over art, etc.); an opera on video/audio laser disc, for example, can be far superior as a total artistic experience to an audio-only CD or LP. Nor do we feel that optional and controllable signal processing is an impure audio influence; for your Bach partita you switch it out of the signal path and listen to your super clean stereo channels straight through. Even in such a case, however, we would not be averse to seeing the soloist in front of us on the big screen for added you are-there-realism. In that spirit, we welcomed the opportunity to review the new and obviously high-quality VPM 600 as our first foray into video territory. Eventually we hope to have video equipment reports in every issue, our chastity in audio matters remaining nonetheless unsoiled.

The VPM 600 is a video monitor without receiver, capable of projecting an image generated by three cathode ray tubes on screens up to 16 by 12 feet in size (20 feet diagonally). Harman/Kardon is the marketing organization behind the video products bearing their logo, not the manufacturer; the VPM 600 is made in Germany by ITT and is the new updated version of the very similar VPM 500, so new in fact that the manuals we received with it had not been changed yet from the VPM 500. The discontinued Kloss projection monitor was also very similar.

The relatively rare breed of front-projection TV's raises the basic issue of image size vs. picture quality. No question about it, something like the Zenith 35-inch direct view set with its single giant tube will give you a more nearly perfect picture than the Harman/Kardon. Even the biggest of the rear-projection sets with three cathode-ray tubes, the Mitsubishi 60-inch model, provides somewhat greater clarity and detail. On the other hand, there is some thing about a really large image, 7 feet or more diagonally, that creates an impression of greater realism than a sharper but much smaller picture. We relate more immediately to life-size people, animals, footballs, chairs, etc. We see more when the scale is that of the real world. For example, on the VPM 600 with a large screen, your Editor's dog-show videotapes revealed much more clearly why certain dogs were winning or losing than on a high-resolution 19-inch set.

Ball games and other sports action are easier to follow on the big screen, regardless of resolution, and lavishly produced color movies with crowd scenes, etc., are simply more enjoyable. Even so, when it comes to an actual buying decision, the trade-offs of front-projection TV must be care fully weighed. We are definitely in favor of it.

Once it is decided to go with front projection, the VPM 600 looks like an outstanding choice, mainly because of its uniquely sophisticated installation and setup features.

Other designs might give you equal or better performance under one specific set of conditions, but no other projection TV known to us permits any screen size between 6 and 20 feet diagonally, and certainly no other set offers comparable precision, ease, flexibility and repeatability in focusing, geometric alignment and color convergence. The controls and test patterns for these adjustments are most impressive; our only regret is that the somewhat cumbersome cover of the unit must be skillfully removed to gain access to them-why not a concealed control panel of some sort? Is the consumer that untrustworthy? A small point; more important to remember is that performance is irrelevant unless it can be optimized under any and all circumstances, and the VPM 600's design assures just that.

In terms of video performance the Harman/Kardon sets no records; nearly all of its competitors are equal to or ahead of it in brightness and resolution, but we do not feel that the user will be even marginally deprived of picture quality as result because his start-up alignment will be so much more precise. Not that the performance figures are in any way unsatisfactory. The video bandwidth is 4.0 MHz, resulting in 320 lines of horizontal resolution. That is good enough to take almost (not quite) full advantage of state-of the-art signal sources such as S-VHS video cassette recorders (the special input socket for these is provided) and laser disc players. The RGB (red, green, blue display) bandwidth is 6.5 MHz, which translates into 520 lines. Brightness (light output) is 300 lumens, about average for front projection TV's. Black level retention (the ability to hold solid blacks) is also average.

Performance figures give no indication of how nice it is to use this set, how well the remote control works (it even provides a quick test and touch-up adjustments for color convergence), and how reliably and repeatably every part of the unit functions. Each time we had a minor problem, it turned out to come from the VCR, not the monitor. All that can be expected to add up to long-term satisfaction.

We would recommend a flat screen to all users of the VPM 600 who can darken the room before viewing. Start up alignment is easier, more precise and more repeatable on a flat screen. Where the ambient light is relatively strong, a curved screen is indicated, but even that works best in a darkened room, and some people will never be happy with the slight optical weirdnesses caused by the curvature. We would also recommend mounting the VPM 600 on the ceiling wherever possible because it is large enough to be a traffic hazard on the floor or even on a table. Sooner or later somebody will kick it or bump into it, and the six-thousand dollar incision in your bank account will begin to ache, not to mention the possibility of having to align everything all over again.

Loudspeaker System

KEF Model 107

KEF Electronics of America, Inc., 14120-K Sullyfield Circle, Chantilly, VA 22021. Reference Series Model 107 floor-standing 3-way loudspeaker system, $4500.00 the pair. Tested samples on loan from distributor.

This is possibly the most difficult review we ever had to write because of the conflict between our awed respect for the engineering of the product and our disappointment in its sound. Let us try to sort out the complexities of this baffling situation.

The English firm of KEF Electronics has been one of the heroes in our audio pantheon for many years; on the subject of loudspeaker technology, they stand for just about everything we believe in and are opposed to everything we dislike. Laurie Fincham, as Technical Director of KEF, was among the earliest advocates of computer-aided loudspeaker design; KEF was the original sponsor of Siegfried Linkwitz in the development of computer-optimized fourth order crossover networks for commercial speaker systems; and KEF was the only speaker company smart enough to entice Richard Small (the Richard Small) to leave academia and join their staff. We are certain that Dr. Small was in some way involved in the design of the Reference Series Model 107, the company's new flagship speaker, and that alone is enough to intimidate us in our attempt at a fair and rational critique.

As if to make things still harder for us, another of our heroes, Don Keele (who signs his outstanding engineering papers as D.B. Keele, Jr. and has been cited by us before), made his debut as an equipment reviewer in the February 1988 issue of Audio with a devastatingly thorough and scholarly test report on the KEF 107, in which he proves that it is an amazingly accurate small- and large-signal transducer and says absolutely nothing negative about the perceived sound of the speaker. We recommend this 8-page "Equipment Profile" to all of our readers who want to see how a real pro goes about testing such a device. Our own measurements revealed nothing to contradict any of his findings-he works for Techron/Crown and used the Techron TEF System 12 analyzer, which is undoubtedly more sophisticated than our not-so-new instrumentation-so we shall treat his published data here as facts (and his favorable subjective observations as opinions).

The Model 107 is a floor-standing 3-way design with a very interesting bass system incorporating two 10" woofers, a separate swiveling "head assembly" housing a 5" midrange driver and a 1" cloth dome tweeter, plus an active line-level equalizer known as KUBE (proprietary alphabet soup), which goes into the tape loop or between the preamp and the power amp. The two woofers exhaust from separate sealed enclosures into a shared ducted cavity, with their magnets linked together by a metal rod for resonance cancellation, a configuration familiar from the Model 104/2.

Front-loading a closed-box woofer with a Helmholtz resonator is not a new idea (John Marovskis, un-credited by Don Keele, has been doing it since the mid-1970's in his Janis subwoofers); it combines some of the advantages of both closed-box and vented-box systems but allows only low frequencies to emerge from the duct, so that the woofer-to midrange crossover frequency has to be much lower than in a more conventional 3-way system, thereby potentially stressing the bottom end of the midrange driver. Neither the type of crossover network nor the crossover frequencies are specified by KEF for the Model 107; logic, combined with our explorations of the sound field by B&K microphone, would suggest a Linkwitz-Riley fourth-order network with one crossover point between, say, 130 Hz and 160 Hz, and the other around 3 kHz. That division (confirmed by Don Keele's estimates) assigns more than four octaves to the little plastic midrange cone with butyl rubber surround, raising some issues to be addressed below. The ferrofluid cooled dome tweeter with its short quasi-horn operates very happily between 3 kHz and 23 kHz.

The frequency response of the speaker is almost spookily flat with the optimal settings of the KUBE. The unequalized response rolls of at 12 dB per octave below 35 Hz (typical closed-box profile) and it shows a very slight elevation of the two octaves from 1 kHz to 4 kHz, but the flattest obtainable equalized response on axis is contained within a 4 dB strip (i.e., +2 dB) from 20 Hz to 20 kHz.

Unbelievable, yes, but verifiable by ear: this baby goes down really low and up really high, with impeccable balance and no spectral signature of any kind, at all levels, soft and loud. The 23 dB of available equalization at infrasonic frequencies necessitates a damn good power amplifier, though; on the other hand, we found the KUBE to be quite forgiving of very high-amplitude inputs, even if its integrated op amps may not reassure the purist. You should read the Keele review for all kinds of data on the speaker's single-frequency distortion, power handling, and so forth, all of them pretty amazing. This is a high-tech loudspeaker system if there ever was one.

In the time domain, the Model 107 is equally impressive. All drivers are in phase, moving forward in response to a positive pulse; square pulse replication is not quite as perfect as we have seen in some 2-way systems, but we have never seen better in a 3-way. Don Keele's energy-time response curve is probably a more revealing test, and it is beautiful, as are his phase and group-delay curves, which we did not find necessary to verify. Tone burst response, not shown in the Keele review but sometimes the easiest way to see various kinds of ringing, looked very good too.

So-this is the perfect electrodynamic loudspeaker, and yet... How should we put it as fairly and temperately as possible? We did not fall in love with the sound, accurate and well-balanced as it was. We heard a certain degree of veiling, or let us call it non-transparency, in comparison with speakers such as our old, discontinued Fourier 8¢, which the KEF beats in so many other ways, and at high levels we even heard some ugliness, especially on piano music. As we kept listening, the pleasure diminished with familiarity instead of growing. We realize that we are beginning to sound here like the self-indulgent subjectivists whom we detest, such is the intellectual/emotional frustration the KEF came to represent to us, but unlike those worthies we shall at least try to rationalize our feelings.

We can think of no more than three possible causes of our disappointment, and the first two are not terribly convincing. There is the so-called conjugate load matching (CLM) network of KEF, which introduces various complex impedances complementing each driver, so that the overall impedance of the speaker system is a purely resistive 4 ohms from 20 Hz (yes!) to 20 kHz. We have never dealt with such a network, which theoretically should be easier on the power amplifier than any other, but who knows what the actual transient interface conditions are? Okay, pretty lame, that one. Next, we have a rather obvious 3 kHz dip in the vertical (but not the horizontal) off-axis response of the 107, shown in the Keele review and confirmed by our own measurements. We believe we have nailed the cause of it, which is certainly not the non-diffractively contoured head assembly but probably the fact that the "naked" midrange driver begins to roll off naturally at 3 kHz, right at the crossover point, instead of providing the overlap necessary for this kind of network. Vertical lobing, however, is not associated with the kind of sonic deficiencies we heard, so that too is a lame explanation. Here is our best shot. Even Don Keele, who liked everything about the sound of the KEF, points out that there is quite a bit of intermodulation distortion, with 250 Hz and 2 kHz mixed 1:1, at levels far below the power-handling limits of the speaker. Both of those frequencies are handled by the midrange driver, which is quite clearly overburdened, as we already implied above. The biggest and most information-rich part of the music all has to be funneled through that little flexible poly propylene cone. KEF should have opted either for a more conventional bass system allowing a higher woofer-to midrange crossover frequency, say 400 Hz, or else for an additional lower-midrange driver to make the Model 107 a 4-way system. The conceptual beauty and lean elegance of the design as it stands may be its hidden weakness, at least in the opinion of one reviewer.

Record & CD Cleaning Machine

Nitty Gritty Hybrid

Nitty Gritty Record Care Products, Inc., 4650 Arrow Highway, Unit F4, Montclair, CA 91763. Model Hybrid 2 record and CD cleaning system, in solid oak cabinet, $599.00. Tested sample on loan from manufacturer.

Keeping phonograph records clean is like brushing teeth, unquestionably necessary but an obsession with some people and merely a routine with others. We have always kept our LP's satisfactorily clean from the first play, with just ordinary care, so that machine cleaning them never made a dramatic difference in listening quality. It is, how ever, the best way-with really filthy records probably the only way-and Nitty Gritty has been the commonsense industry standard ever since the esoteric Keith Monks machines priced themselves out of the market. V.P.L. is the available alternative; we have no opinion on that subject, having had no experience with the latter.

The Nitty Gritty Hybrid intrigued us because it is the first machine to offer both LP and CD cleaning in a single unit. Now, cleaning a CD is rarely necessary; the disc is easier to handle without soiling than an LP, and the very method of playing it is inherently clean; on the other hand, some bozos still think a CD is rugged enough to be used as an ashtray or as a Frisbee, and they clog up the microscopic pits beyond the clairvoyant powers of the Reed-Solomon error-correction code. In such a case a thorough cleaning that avoids circular motion (in the direction of the pits) is indicated, and the Nitty Gritty gadget is just the ticket.

What Nitty Gritty did was to take their trusty .5Fi series design, which is next to the top of the line, and add to it an eccentric capstan adapter to "de-circularize" the cleaning motion. You place the CD on the adapter, apply "Pure CD," which is Nitty Gritty's proprietary CD cleaning fluid, start the motor, and lower the buffing pad glued inside the integral acrylic dust cover onto the pitted side of the CD. It is rather primitive but it works just fine. The CD comes out spanking clean. Of course, you are supposed to remove the strawberry jam or whatever before you put the CD into the machine; the buffing pad is not a garbage disposal unit, which the vacuum cleaner section for records almost is.

The Hybrid 2 is identical to the Model 2.5Fi in its record cleaning aspects, and the job it does is essentially impeccable. The vacuum motor is very powerful and quite quickly removes all traces of the "Pure 2" record cleaning fluid, which one learns after a few tries to inject into the velvet covering of the hemi-cylindrical cleaning slot in the correct quantity, without spills. The system is somewhat crude, not at all Swiss-watch-like; the sounds it makes are not always reassuring; but it works every time, and that is what a good tool is all about. Unlike the top-of-the-line Mini-Pro model, the .5Fi series cleans one side at a time, which is good enough for us. Do not imagine, however, that clicks and pops are removed along with the grit noises.

When you clean a dirty and scratched record with the Nitty Gritty machine, what you get is a beautifully clean and scratched record. (One reason why we are CD enthusiasts.) Phono Transducer Win FET-10 (follow-up)

Win Research Group, Inc., 7320 Hollister Avenue, Goleta, CA 93117. FET-10 Field-Effect Transducer with Source Module, $2250.00. Tested sample on loan from manufacturer.

Having tried our very early sample of the FET-10 in a number of systems with different gains and efficiencies, we are now inclined to regard the hiss level from the fixed out puts of the unit to be higher than we would want to live with permanently. We have been assured by Sao Win that the version about to go into production is vastly superior in this respect. We hope so because the fixed outputs are what audiophiles with preamplifiers are going to use, even though the variable output connection without a preamp is the ideal way to deploy the FET-10.

As for Dr. Win's channel separation table in his letter to the Editor (see page 8), we own a perfect copy of the JVC TRS-1007 MK II test record, obtained directly from JVC in 1981, but we have been unable to duplicate with it the high separation figures claimed in the table. Unless and until this discrepancy is resolved-and there could be any number of reasons for it-we must stick with our original comments on the channel separation specs of the FET-10.

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[adapted from TAC, Issue No. 12]

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Also see:

The Digital Scene: More Theory, More Facts, More Hardware -- Harman/Kardon HD800 ; Onkyo Integra DT-770 ; Philips CD880 ; Philips CD960 (follow-up) ; Philips DAC960 ; Precision Audio D1 Analog ; Yamaha CDX-5000

Further Thoughts on Double-Blind Listening Comparisons at Matched Levels

Various audio and high-fidelity magazines