In this sequel to our comparative survey of 22 preamplifiers, we review two updated models plus three entirely new ones, reconsider all those that accept moving-coil cartridges, report on four preamp accessories, fine-tune all of our preferences, and come close to giving up on a sonically correlatable lab test.

Before we get into the meat of this follow up report, we'd like to clarify something about our basic attitude that appears to have been misunderstood, or at least incompletely under stood, by some of our subscribers.

When we describe the sound of a preamp in purely subjective terms, such as "hard" or "open" or "lacking depth," without being able to offer any specific laboratory data in support, we do so with a certain degree of frustration and even embarrassment. To us it's an unavoidable evil, not something to groove on. Yet we have the feeling that this is the part that some audio freaks like best, that they would move on to another hobby if, say, "hardness" could be measured on Mohs' scale as in a mineral.

And they probably find us insufficiently expansive in our subjective observations; we don't dwell long enough on the "depth" or the "grain," like a pornographer on the heroine's anatomy.

The truth is that we'd like to get even further away from that kind of description;

we'd much rather say, "Look, guys, it just doesn't sound right and everyone on our staff agrees," and then go back to the laboratory to keep digging for the reason why. What's more, we're not too comfortable about rating one not-quite-right sonic performer a little higher than another. That's really subjective. So if your Nirvana is a place where all day long they say things like "You're wrong, man; the C-2 is even grainier than the PAT-5," then The Audio Critic may not be your Buddha. We aren't the least bit pleased that the ear has the last word.

We just accept it.

The reason why we're bringing up all this in the middle of our preamp survey is that we're

at our wit's end trying to find a correspondence between the measurable and audible characteristics of preamps, whereas we find excellent laboratory support for the differences we hear among speakers or even power amps. (See our power amplifier report in this issue.) Is it be cause preamps are more nearly perfect than other components? But then why do a few of them sound so much better and a few of them so much worse than all the rest? We're absolutely certain that, since the ear is a sensor of a certain resolving power, measuring instruments of even higher resolution can give us even more precise answers, if only we knew how to ask them the right questions. Until then, it's your golden ear against my golden ear, fella, and frankly that's not good enough for us.

Who's got the test? We made a point of quizzing some of the most highly regarded preamp gurus and circuit designers about the electronic reasons for a preamp's sound in general and correlatable lab tests in particular. They included Mark Levinson and Tom Colangelo of MLAS, Tom Holman of Advent (now on his own), Dave Spiegel of AGI, Dave Hadaway of D B Systems, John Curl (independent consultant), Carl Marchisotto of Dahlquist, Mark Deneen of Paragon, Andy Rappaport of A. S. Rappaport Co., Stew Hegeman of Hegeman Labs, Ike Eisenson of Audio Dimensons. Each of them has very strong opinions about correct and incorrect circuitry, but not one of them is willing to name a laboratory test, or even a series of tests, that will unequivocally separate the best-sounding preamp. That leaves us in a rather lonely quandary trying to follow through on the issues we raised in Part I (pages 7, 8 and 9), so we'll have to be somewhat circumspect as we report what we have, and haven't, found out since.

The Holman square-wave test has been pretty conclusively laid to rest by Dr. D. Preis of Harvard (Journal of the Audio Engineering Society, January/February 1977, pp. 9-12), and we note that Tom Holman himself is obviously soft-pedaling the subject in his most recent article (Audio, February 1977). We furthermore suspect that the Otala 'sine square" test, which isn't mentioned by Dr. Preis, also suffers from the limitation pointed out by him, namely that impulse testing that drives a circuit into transient overload doesn't provide useful information about the performance of the circuit under normal operating conditions. We certainly haven't been able to make the Otala test work for us. As for the Hetrich gated asymmetry test and the proposed Rappaport square-sine-square test, we're still working on their implementation. (We'll keep testing preamps one by one, of course, even if there won't be another broad survey for quite a while.)

Real depth vs. phony depth.

We do feel fairly confident, however, about one correlation between measurement and sound that we've had a chance to look into since the publication of Part I. We believe that harmonic distortion in the preamp can create an impression of greater spatial depth in the reproduction than was actually captured by the microphones and engraved in the record groove.

An early, unfinished prototype that passed through our laboratory provided the best example. This preamp exhibited second and third harmonic distortion in the top octave (10 kHz to 20 kHz) of the order of 0.1% to 0.25%, depending on the frequency, at rated output (meaning nowhere near clipping). Its sound had stupendous depth, along with just a suggestion of fuzziness ('hair on the highs) that eventually proved to be slightly fatiguing.

Weeks later we heard a cleaned-up version of the same circuit, with much lower harmonic distortion, beautifully focused highs-and considerably reduced depth, not very different from what we could hear through other good preamps.

Several more preamps we have measured recently fall into the same pattern. The CM 300, for example, has easily measurable low order harmonic distortion (although well within the conservative 0.05% spec), and its sound has great depth as well as-wouldn't you know it-a slightly edgy quality.

On the other hand, certain preamps with ultralow harmonic distortion and ''grainless" highs, such as the Mark Levinson JC-2 and the D B, are frequently accused of deficient depth perspective, even when they undeniably repro duce depth in recordings that were micro phoned with special attention to the front-to- back dimension (e.g., the English "Siegfried" on EMI). So the question is, how much depth information is there in the groove itself and how much depth illusion is added by the play back electronics? (Yes, we know; we too faulted the JC-2 for spatial compression-but hold your horses, there's more.) The question has two sides, as usual. It has been argued that extremely low harmonic distortion is achievable only with circuit design techniques that increase the chance of TIM, which in turn creates a time smear that obscures depth information. Hence a little harmonic distortion and good depth imaging go hand in hand. Andy Rappaport is an exponent of this point of view. (His preamp has low, but not vanishingly low, high-frequency distortion and outstanding front-to-back definition.

He claims to have judiciously fine-tuned the trade-off.) The other argument denies that all circuit designs without exception involve such a trade-off and implicates harmonic distortion as a source of false ambience information, since the majority of commercial recordings are lacking in genuine ambience. Mark Levinson takes this position and points out an interesting phenomenon that has been observed by a number of audio experimenters. In an optimally biased amplification circuit, turning the bias down to the point where nonlinearity sets in and harmonic distortion begins to rise creates an impression of greater depth in the reproduction. Turning the bias up again creates the impression that the depth perspective has been

"ruined," until one realizes that the restored linearity makes the sound less fatiguing, more nearly '"'right"-in other words, accurate. All this without circuit changes.

We're strongly inclined to accept Mark Levinson's argument, and the clincher is pro vided by his latest product. The new, revised JC-2 (the one with Lemo connectors and a new power supply) combines what sounds to us like accurate reproduction of ambience information along with even purer, more luminous highs than before. Apparently the subtle spatial compression in the older version was a power supply problem, since the latest circuit modules in the signal path incorporate only minor clean up changes-and certainly not an extra sprinkling of THD.

We'll rest our case on this subject, until further evidence accumulates.

One other measurable characteristic that we believe correlates with listening quality is band width limiting, provided it's sufficiently severe.

A preamp that completely lops off the corners of square waves will sound like what it is electrically: a transient filler. The Bravura, re viewed for the first time below, is a perfect example.

The moving-coil tests.

To complete our preamplifier survey, we retested each preamp that accepts a moving coil cartridge, whether through its 'mag phono" input by virtue of sufficient gain or through its own moving-coil electronics (pre preamp or head amp, built in or accessory).

The cartridge used for these tests was the EMT Model XSD 15, the best-sounding MC cartridge known to us; indeed, probably the best-sounding cartridge of any type. Both the inner detail and the dynamic range revealed by the EMT are extraordinary; however, it seems to be less forgiving of not-quite-superb electronics than most others, which of course made it particularly suitable for our tests. The Denon DL-103 and DL-103S were used as backup cartridges;

these are also outstanding units of course, but the EMT is our favorite.

It could be argued that, since all of the above MC cartridges have relatively high out put, we weren't testing some of the pre-preamps and head amps to the limit of their gain and noise characteristics; also that input overload might have raised its ugly head in some in stances. Our answer is that (1) we were trying to zero in on subtle differences in sound quality and therefore had to use the best-sounding cartridges known to us, and (2) all of the more sophisticated MC circuits tested had some kind of provision for adjusting their gain to suit the cartridge, so there's every reason to believe that their relative ranking would have been the same with a low-output test cartridge.

(Incidentally, let no one assume that we have turned our back on the remarkable Grado Signature magnetic cartridge, which has under gone something of an evolution since our previous comments. We plan to report on the "final" version as soon as Joe Grado stops messing with it.) The tone arm we used with these cartridges was the Dynavector DV-505, a highly unorthodox, elaborate and costly pivoted arm, slated for review by The Audio Critic in the very near future. It has some flaws, but we were able to make it perform extremely well for us; furthermore, the adjustments that must accompany cartridge changes are unusually quick and precise with this arm.

In fact, the especially stringent demands we made on our cartridge/arm combination for these tests changed our perspective to some degree on the subject of tracking error. In the tone arm article in our first issue we glossed over the audible effects of tracking error, while deploring it as a symptom of mathematical know-nothingism. We're now of the opinion that both lateral and vertical tracking error must be minimized to the inherent limits of pivoted-arm geometry when setting up a critical listening test. (See also the letter from Mitchell Cotter we have published here, which touches on this subject in its exegesis of the moving-coil cartridge.) In all other respects, our methods, testing philosophy, source material, pet peeves and platinum ears were the same in these tests as in the mag phono comparisons covered previously. To refresh your memory, refer back to Part I of this survey in our first issue; we won't repeat ourselves here. In fact, the follow-up reports below on eight previously tested items may not be sufficiently informative without reference to the original reviews; these we have marked with an asterisk (*). Among the new units reviewed, the Mark Levinson and the Rappaport are only partially new, evolutionary models that also require reference to the original reviews for complete understanding.

With that caveat, we can begin.

AGI Model 511* For manufacturer, price and other particulars, see original review in Part I.

We have upgraded our estimate of this preamp since listening to it with the EMT cart ridge, for which it has adequate gain. The peculiarities of front-to-back imaging we had noticed with the Grado Signature cartridge seemed to be less evident with the EMT, and we were impressed by the smoothness and openness of the sound, especially in com parison with other preamps we had previously put in more or less the same class. The EMT has a way of making marginally good preamps sound '"'electronic," but the AGI passed the test very nicely. (That still doesn't make it a Mark-Levinson-buster, as some have suggested.) Considering its ability to deal with both magnetic and high-output MC cartridges, the AGI looks to us like an outstanding value at $400.

Audio Research SP-4

For manufacturer, prices and other particulars, see original review in Part I.

The plug-in head amp announced for this unit was not available in time for these tests.

Instead, we received word of a $200 increase in price-without head amp. That makes the SP-4, at $895, one of the most expensive mag-phono-only preamps on the market. It will, however, play the EMT moving-coil cartridge without running out of gain, and we did retest it that way.

Since our original report, the SP-4 has considerably declined in our esteem. For one thing, the slight hardness and sibilance we pointed out has a way of growing on you- negatively. By now we think of the SP-4 as positively zippy. (Of course, the EMT is a very sensitive zip detector.) Then we were disappointed to discover that the "matching" Audio Research D-100 amplifier doesn't make the SP-4 sound better; it makes it sound zip pier than the Quatre does, despite the D-100's somewhat bandwidth-limited response (see our power amp survey in this issue). On top of that, a number of very keen-eared people have assured us that we have an exceptionally good sample of the SP-4, the best one they had heard. It appears that most of them in the field sound worse.

The clincher, though, came when we connected the Hegeman HIP Input Probe (see review below) between the cartridge and the mag phono input of the SP-4. With the probe set for unity gain, the sound became sweeter and the bass considerably better. That seems to indicate that the first stage of the SP-4 circuit leaves something to be desired, since the Hegeman unit is of no use where every thing is perfect to begin with.

Incidentally, we haven't heard a peep out of Audio Research since we challenged them to deny that the Analog Modules are nothing more than IC's. We can't help but interpret their silence as an admission. Our suggestion is that they consult someone like Mark Levin son or Andy Rappaport about good discrete transistor circuitry.

Bravura Nexus Engineering, 9116 Orlando Place Northeast, Albuquerque, NM 87111. Distributed by Audio Arts, 4208 Brunswick Avenue North, Minneapolis, MN 55422. Bravura Stereo Preamplifier, 3500. One-year warranty; customer pays all freight. Tested #BI110, on loan by courtesy of Audio Den Ltd., Stony Brook, NY.

Before we tested the Bravura, we were warned by its partisans and promoters that the only way to evaluate it was with the Shure V-15 III G cartridge and the Fulton J speaker.

Furthermore, the instructions direly warn that the use of any cartridge with a DC resistance of more than 2600 ohms, or any pre-preamplifier that is AC-coupled, will void the warranty.

"Best operation," according to the makers, is with a cartridge having a DC resistance of 1400 ohms.

This led us to speculate about a preamplifier that must only be used for listening to Tibetan music while sitting on yakback. We've heard all about compatibilities and incompatibilities in audio components, but in the case of the Bravura we seem to be dealing with quarantines and allergies.

In the firm belief that, if the Bravura was any good at all, it would sound fairly decent in our reference system, we inserted it into the setup used for Part I of this survey. It didn't sound fairly decent.

The best way to form an idea of the sound of the Bravura is to think of it as a transient filter. It makes everything sound nice and smooth, without a trace of harshness, but the transient detail that makes music come alive is simply missing. For example, in flamenco guitar music the strings sound dead because the starting transient of each pluck is obliterated. As a matter of fact, any kind of music sounds disturbingly lackluster through the Bravura. No transients, no sparkle, no life.

Our laboratory investigations revealed a real mess inside the little black box. For example, the phono input overload is around 12.5 mV. Ever heard of such a thing? But that's not all. When you try to find out what's wrong with the phono stage, it turns out that nothing is wrong. It's the high-level stage that's overloading, beginning at about 300 mV in put. Since that's the approximate output of the phono stage with 12.5 mV input, there's the explanation-but not the rationale. Actually, the phono amplifier by itself sounds quite decent, but you have to tap it electrically to be able to listen to it, since the tape output is placed past the high-level stage. (Ha-ha, fooled you.) It's in the balance control network, though, that the Bravura goes bananas. With the balance controls (there are two of them, for left and right channel levels) turned all the way down, there's a 50% overshoot on square waves. With the balance controls turned all the way up, the square waves are severely (and we mean severely) lopped off. To us, this circuit looks like an afterthought, as if the designer hadn't liked the sonic results up to that point and decided that it was too late to go back to the beginning, but something had to be done before the output. The instructions recommend that we use the blunted-square-wave range of the balance controls (" 9 o'clock is excellent"). The mind boggles.

We really don't know what to make of the Bravura. If you're into the Fulton J scene, you probably know all about it, since it's distributed by Audio Arts, one of whose owners is named Fulton. In that case you don't need to ask our advice. If you do, don't ask.

CM 300 Audio International, Inc., 3 Cole Place, Danbury, CT

06810. CM 300 Stereo Control Center, $549. Tested #1008, on loan from manufacturer.

Like the CM 912a power amplifier re viewed elsewhere in this issue, the CM 300 is made by the successor of the former C/M Laboratories; in fact, its chassis is styled to match that of the companion power amp, big handles and all, making it a little inflated in size considering its innards.

As in the case of the CM 912a, the CM 300 was in our possession for a very limited time only, but long enough for us to establish definitively that it's neither the best-sounding preamp in our survey nor even the best per dollar. But it's good; you could even argue very good.

One nice feature of the CM 300 is that the gain of the phono stage is adjustable; it can be matched for optimum S/N and overload (within its capabilities) to almost any cartridge, including MC types with medium to high output. The sound is very spacious, well focused and just the least bit edgy (or call it fizzy); we have already noted in our general discussion of depth perspective the correlation between this kind of sound and the amount of harmonic distortion measurable in the CM 300 (0.03% to 0.04% at the higher frequencies). In addition, the square wave response of the CM 300 shows an asymmetry (normal on positive part of cycle, quite rounded on negative); ac cording to the Audio International engineering department this is inaudible and would need an extra stage to eliminate, with more noise to pay as the penalty. Okay, but what about pre amps that have beautiful square wave response and low noise? We're being somewhat critical of the CM 300 just because we feel that it could be even better, and to the best of our knowledge the design is still in a state of flux, since the unit has so far been produced only in small quantities.

Who knows, maybe its makers will diddle with it until it's a real winner.

DB Systems DB-1/DB-2/DB-4

For manufacturer, prices and other particulars, see original review in Part I. Add-on unit reviewed here: DB-4 Pre-preamp, $150. Tested #4130721, owned by The Audio Critic. Backup sample #4051226, on loan from manufacturer.

Retesting the D B preamp with a moving coil cartridge through its add-on pre-preamp has left our opinion of it virtually unchanged.

The DB-4 doesn't seem to alter the basic sound of the DB-1; only the noise level goes up a little bit.

We still believe that the D B sounds some what more aggressive and "'electronic" than, for example, the Mark Levinson JC-2; the latest, revised version of the latter makes the difference even more obvious. Our promised investigation of the DB's apparent lack of low bass impact hasn't yielded any conclusive result, but that was never our principal reservation about this unit. Its failure to sound utterly unstressed and natural (but only in com parison with a very few others) is the only damper on our unqualified enthusiasm.

Dave Hadaway has sent us an interesting preamp bypass test box, with which it can be demonstrated that the insertion of the D B into a signal path does rot result in any audible change in sound quality. Very impressive; but we aren't convinced that the buffer chip that remains in the test circuit in all modes inter faces with the preamp in exactly the same way as a phono cartridge. Nor that it doesn't mask key information in the bypass mode. But the test is certainly a powerful argument in sup port of the D B's accuracy. We're virtually certain that, deep down, Dave Hadaway believes that it's the program sources that are "aggressive" and that other preamps may have a prettifying effect on them.

Luckily, the argument need not be urgently resolved, since the DB-1/DB-2/DB-4 combination is the only preamp system today selling for $575 that can process any phono signal, from the lowest to the highest level, with this degree of quality.

GAS Thaedra For manufacturer, price and other particulars, see original review in Part I.

We said in our original review of Thaedra that testing it with a moving-coil cartridge would be a whole new ball game, since the "servo-loop" head amp feeds directly into the high-level stage instead of being in tandem with the mag-phono preamp. We were wrong. The Bongiorno sound came through just the same.

It's a very good sound, mind you. Round, smooth, grainless and just plain nice, without any obvious loss of detail. Just what the high end customer likes to hear when he walks into an audio salon. But it still isn't an accurate sound. It wraps stark transients in whipped cream, as we said; or maybe in zabaglione. . . ? When A-B-ed against the new, revised Mark Levinson JC-2, the Thaedra doesn't even put up a good fight. The JC-2 sounds significantly more open, transparent and real, much more in palpable contact with the music.

Incidentally, the Stax SR-X Mark 3 electrostatic headphones spell out the difference even more vividly than speakers, but did you ever try to make an anthropoid ape put on a pair and really listen?

Hegeman HIP Input Probe

Hegeman Laboratories, Inc., 555 Prospect Street, East Orange, NJ 07017. Model HIP Input Probe, $135 with battery pack, $160 with AC power supply. Two-year warranty. Tested #70, on loan from manufacturer.

What is it? It's a little box that goes under, or next to, your turntable, with the shortest possible leads from your tone arm plugged into it 18 and its output connected through any length of cable to the mag phono input of your preamp.

What does it do? In some cases absolutely nothing. In other cases it improves the sound considerably. You won't know till you've tried it.

How does it do that? By means of a circuit that has unity gain, virtually zero input capacitance, extremely flat and wideband response, and very low output impedance. If the first stage of your preamp has some faults, this may be exactly the kind of interface between it and the phono cartridge to make those faults inoperative and irrelevant. (It will also give you a gain of 12 dB at the flick of a switch, which makes it a kind of low-gain-but not particularly low-noise-pre-preamp.) What else? It's powered through an umbilical cord from a separate little power supply box. It will also accept a tape head input.

And it was engineered by the legendary A.

Stewart Hegeman, who was designing accurate speakers and audio electronics back in the days when most people's idea of good sound was a Stromberg Carlson.

We tried the Hegeman probe with a number of preamps and obtained varying results.

For example, it didn't do a thing for the Rappaport PRE-I; if anything, it introduced a slight amount of veiling. On the other hand, it improved the Audio Research SP-4 (which isn't exactly a piece of garbage) quite spectacularly; the highs became much sweeter and the low bass suddenly emerged, with impact and detail. And our jaw dropped.

What this unit will do for your run-of-the mill stereo receiver or integrated amplifier, we have no idea. Its price makes it an afford able upgrade for that type of installation, even if sonically it cuts across the high-end scene as well.

We left the best for last. A complete Hegeman preamp, with an input stage very similar to the HIP, is in the works. We've heard the prototype, and it's more than just good.

It promises to be a state-of-the-art contender.

Mind you, we didn't say challenger, let alone winner. We don't know. But it will have to be carefully A-B-ed against the best. And it won't even be terribly expensive. Stew Hegeman still seems to have the touch.

Mark Levinson JC-2 (new)

Mark Levinson Audio Systems Ltd., 55 Circular Avenue, Hamden, CT 06514. JC-2 Preamplifier, with plug-in System A3 for magnetic cartridges and System D5 or D6 for moving-coil cartridges, $1475 complete. Five-year warranty; customer pays all freight. Tested #2221, owned by The Audio Critic.

In an editorial postscript to our original review of the JC-2 in Part I of this survey, we twitted Mark Levinson for what looked like an extravagant and impractical new version, the news of which had just reached us. Well, a number of weeks later the revised JC-2 reached us, and now we're singing a different tune.

This is simply the finest preamplifier heard so far by our staff. Will you ever forgive us, Mark, for our peevish indiscretion? Here are the changes in the JC-2: New power supply (PLS-150), totally different from the old one. New power supply filter module.

Lemo connectors, instead of the standard RCA-type phono jacks (more about that in a moment). Reworked amplifier modules, with even higher slew rates (Andy Rappaport, please note) than before. New (and more versatile) plug-in cards for mag phono and MC. And a second phono input instead of the previous "remote" input. All this begins with serial number 2148.

The Lemo connectors are incompatible with the standard RCA connectors of the audio industry. We spent in the neighbor hood of $100 for adapters, just to connect up the most important units in our system.

And we still don't have enough of them.

And yet-we just love the Lemo. It's a little jewel, made with watch-like precision in Switzerland. If you're familiar with BNC connectors (the kind used in signal generators, oscilloscopes, etc.), imagine a highly miniaturized, gold-plated version of it and you have an approximate idea of the Lemo. It makes the ground connection first and breaks it last, so you won't get horrible pops. It can't be pulled out by tugging on the cable, only by grasping it firmly with your fingers. So it really stays put. We could go on and on. If somebody high up said, "One, two, three-go!" and the entire industry switched to Lemo connectors overnight, it would indeed be paradise. That it isn't going to happen doesn't seem to bother Mark Levinson. He and his engineers are very much into the diode effects and other horrors of bad electrical contacts, and they really hate standard phono plugs and jacks. In fact, they feel you ought to remove the phono jacks on all your components and install Lemo female connectors instead. They'll tell you how to do it, too, if you consult them. Religion knows no obstacles.

We were especially amused by the instructions that accompany the phono cable adapter block. This $21 Lemo adapter goes between the tone arm cables and the phono input. The instructions tell you to chop off the plugs on your tone arm leads and solder the latter directly into the block. That of course marries your tone arm monogamously to the new JC-2. In his devotion to sonic purity, Mark Levinson is asking you to put a chastity belt on your system to which only he has the key. But we outfoxed him. Instead of mutilating our $500 tone arm, we soldered very short leads ending in female RCA connectors to the adapter block. Who says you can't have a little fun on the outside, even in the best of marriages? Okay, let's talk about the sound. In the unanimous opinion of our staff, it's in a class by itself. The occasional compression or miniaturization of the sound stage for which we faulted the earlier JC-2 is gone. According to Mark Levinson, it had to do with the power supply, not the amplifier modules. The depth perspective still isn't in, say, the Paragon category, but in our judgment the ambience information that's actually in the record groove is correctly extracted. (See also our discussion of depth, above.) And the overall transparency, openness, inner detail and sheer purity of the sound, throughout the frequency range but most notably on the upper end, cannot be called anything but unique. No other preamp in our experience gives you the same degree of feeling that you can touch the singer or the instrumentalist. Switching to any other preamp seems to create the impression of more electronics and less reality. And that goes for both the mag phono and the moving-coil modules.

Of course, if you feed garbage in, you'll get garbage out. This is no prettifier of inferior program sources.

The obvious question that arises, then, is why this new preamp is called the JC-2. Why

not the JC-2a, for example? Mark Levinson's answer is that any owner of the earlier JC-2 can have his unit converted, in steps or in toto, until it either approaches or is indistinguishable from the new model. It all depends on how much you want to spend-whether you want the Lemo connectors, the second phono input, etc. For example, $65 will get you a new power supply filter module for your old JC-2, which is probably the biggest single change you can make to take it closer to the new version. We tried it and heard an improvement, but not quite like the whole new unit. Mind you, we aren't endorsing this marketing philosophy, just reporting it.

But until we hear something better, the new JC-2 is our reference preamplifier.

MAS 1

Mel Schilling Enterprises, Division of Music and Sound of CA, Inc., 7205 Pomelo Drive, Canoga Park, CA 91307. MAS | Stereo Moving Coil Preamplifier, 3229. Five-year warranty; not clear who pays freight. Tested unnumbered sample, owned by The Audio Critic.

This is an individually available, self powered pre-preamp, offered as the last word in MC amplification. We find it to be some thing less than that.

On the laboratory test bench, the MAS 1 is just about perfect. We couldn't find even one little thing wrong with it; it simply won't mis behave with any input of any waveform.

The sound of the MAS 1 is another matter.

It's a little hard and strident, just enough to cause subtle discomfort on extended listening.

It also introduces a slight amount of veiling or opacity as compared to a bypassed connection.

If we knew why this unit doesn't sound absolutely superb, we'd be a long way toward a sonically valid laboratory test of low-level amplifier circuits.

Paragon Model 12

For manufacturer, price and other particulars, see original review in Part I.

Since the Paragon has a lot of gain, it readily accepts a high-output MC cartridge like the EMT. Retesting it that way has only increased our respect for it; unlike the Audio Research SP-4, for example, the Paragon wears well and grows on you. Not that we have significantly changed our assessment of either its unique virtues or its characteristic short comings; however, we have more or less come to accept it as one legitimate approach to state-of-the-art, though not the one we would have taken.

The lack of a really tight, controlled bass and lower midrange remains our number one quibble, but it turns out that Mark Deneen wants it that way. He told us he could easily tighten up the bass of the Paragon but that, to him, it doesn't sound "real" that way. There, in a nutshell, you have the philosophy of for matted sound, designed to a subjective aesthetic standard. That's why we're so desperately searching for an objective criterion of accuracy.

All this has become less of a judgmental agony for us since the arrival of the revised Mark Levinson JC-2. Until then, we felt there was a possibility that we just might have been wrong and the Paragon-ueber-alles faction right. Next to the new JC-2, however, the Paragon definitely sounds a little "electronic." No doubt about it.

But don't forget that the last word hasn't been heard yet from Mark Deneen. As we mentioned, he is working on the tube preamp to end all tube preamps, which will sell in the four-figure range. In the end, it may well turn out to be the Battle of the Marks.

Rappaport PRE-1A with MC-1

A. S. Rappaport Co., Inc., Box 52, 146 Bedford Road, Armonk, NY 10504. Model PRE-1A Stereo Preamplifier, 8315, with PS-1 Power Supply, $200, and MC-1 Moving Coil Phono Stage, $300. Three-year warranty; manufacturer pays two-way freight. Tested #1003-01 /#2007/ #3013, owned by The Audio Critic.

The remarkable Rappaport, which was our reference preamp until the arrival of the new Mark Levinson JC-2 and still is our backup unit, has undergone a surprising but not illogical evolution in complexity and price.

The original mag-phono-only version, the self-powered PRE-1, was introduced to a few dealers at the mind-blowing retail price of $475.

Before anyone had bought even a single unit from these dealers, the price went up to $495 and then almost immediately to $575, at which price (still a bargain) the first few were sold.

There was a minor hum problem with these early samples, cured in current production models; then, partly to eliminate the slightest trace of hum and partly in anticipation of a new head amp, the power supply was taken out and redesigned as a separate chassis, the PS-1.

Minus the power supply but otherwise identical, the preamp became the PRE-1A, to be followed shortly by the MC-1 head amp (separately RIAA equalized), which also plugs into the PS-1.

So now you can choose either the PRE-1 at $575, or the PRE-1A/PS-1 combination at $715 (no bargain since now the PRE-1 doesn't hum either), or the MC-1/PS-1 combination at $500 (terrific, but you need a volume-controlled system to plug it into), or the whole shebang on three chassis (PRE-1A/PS-1/MC-1) at $1015, which ain't hay.

The most important thing to report here is that the MC-1 through the "aux" input of the PRE-1A sounds even better than the PRE-1 (or PRE-1A) alone through mag phono, not only because of the general superiority of MC cartridges but also because of some minor refinements in circuit design. The MC-1 has a tremendously dynamic, juicy sound with great front-to-back perspective and deep, deep bass.

Rock freaks will flip over it and classical buffs respect it, but we lean strongly toward the new JC-2.

Interestingly, the two preamps sound quite different; the Rappaport being darker and richer in sound; the Mark Levinson more re fined, luminous, etched, and somehow more real. Some will disagree, we know, but that's the way we hear it. Of course, when two reproducers of the same program source sound different, at least one of them has got to be wrong.

Most likely, both are slightly wrong, and all we can try to decide is which one is more nearly accurate. Until, one day, we'll know how to do it in the lab-but then every manufacturer will catch up within a year and we can start picking even smaller nits all over again . . .

We must add that our sample of the MC-1 measured well within specs, while of course exhibiting the low slew rate (approximately I V/uS) which is the Rappaport hallmark.

And that, aside from the revised JC-2, we don't really know of anything we'd rather listen to, even at $1015, than this preamp.

But it all goes to show that SOTA is a sometime thing.

Stax SRA-12S

For manufacturer, price and other particulars, see original review in Part I.

The preamp part of the Stax has enough gain, with the so-called inter-stage amplifier switched in, to accept MC cartridges like the EMT or the Denon, but retesting it that way didn't change our rather negative opinion of it one iota.

On the other hand, we became very fond of the main amplifier stage, which can be used separately with the fabulous Stax electro static headphones to listen to any source, including better preamps.

Stax should know better. If their picture window weren't so clean, people couldn't see how messy their living room is.

Supex SDT/180

Sumiko, PO Box 5046, Berkeley, CA 94705. Supex SDT/180 Step-up Transformer, $150. One-year warranty; customer pays all freight. Tested sample owned by The Audio Critic.

A step-up transformer is the simplest add-on component to provide your preamp with MC capability-and it need not be a compromise, as the example of the Verion proves (see below). But not as this example proves.

The Supex SDT/180 is labeled "Excellent High Quality" (sic), which gives you an idea of its sophistication. The measurements tell the rest: almost 3 dB down at 50 Hz, 5 dB down at 30 Hz, 7.5 dB down at 20 Hz. You call that bass? What's more, at 10 mV out, the THD at 30 Hz is 1.13%, nearly all of which is third harmonic. Even at 100 Hz, there's too much third harmonic (about 0.5%). And at 2 mV out, these figures aren't even halved.

The high-frequency characteristics of the SDT/180 happen to be quite good, but just imagine what the whole thing sounds like with that kind of bottom end.

Yes. That's what it sounds like.

Trevor Lees Mr. Audio, PO Box 4489, Berkeley, CA 94704, or 4 Admiral Drive (#431), Emeryville, CA 94608. Trevor Lees Preamplifier kit, $175; faceplate, 325; Dynaco PAS-3X kit, discounted at approx. $120. This modification voids Dynaco warranty.

Editor's Note: This is not a review or test report, but merely a brief commentary to follow through on our previously announced intention to include the Trevor Lees preamp in our survey.

Meanwhile this product has, in our opinion, revealed some serious credibility problems, and we feel that treating it as a bona fide competitor of other preamplifiers reviewed here might constitute a risk to our own credibility.

The circuit of the Trevor Lees tube pre amplifier is an exact duplicate of the phono stage of the Paragon, up to the latter's tape output. That means tube for tube, resistor for resistor, capacitor for capacitor. The values are mostly identical; in a few instances they differ by a negligible amount. The only circuit component of appreciably different value we were able to discern is a grid resistor that affects gain only.

If you hung a volume control across the tape output of your Paragon and fed the signal from it directly into your power amplifier, you'd be the proud owner of a Trevor Lees pre amplifier with a better power supply-and better built, of course, since the Paragon isn't made from a Dynaco kit.

Now we have absolutely no intention of reviewing the performance of half a Paragon, any more than that of half a Thaedra or half a D B or half an AGI, even if someone had the gall to come out with one in cheap kit form, since the circuits are there for anyone to copy. (Maybe that's why Mark Levinson, Andy Rappaport and others have their circuit modules potted in epoxy resin. It's hard to do that with tubes, though.) You can, of course, bypass the high-level stage of almost any pre amp by using the tape output and thus eliminate the contribution of that stage to the total distortion. You don't need an audio reviewer for that.

As for the expertise of those who originally hailed the Trevor Lees preamp as something totally new, different and wonderful, you can also form your own opinion.

Verion MK1

Verion Audio Inc., 75 Haven Avenue, Mount Vernon, NY 10553. Stereo Pickup Transformer MK 1, $250. Five year warranty. Tested #1S329497, owned by The Audio Critic.

Since a step-up transformer is unquestionably the quietest means of elevating the output of a moving-coil cartridge to the point where an ordinary phono stage can take over, the only question is whether it can have the frequency response and waveform fidelity of the best low-level amplifier stages. We had never seen a transformer that did, until we came across the Verion.

This little 6-inch metal brick is something of a tour de force, since if you simply treat it as a "black box" (actually it's blue) with an input and an output, it's hard to tell in the laboratory whether or not it's an amplifier.

Low-frequency square waves are amazing, the high-frequency response extends several octaves above the audio range, and distortion of all types is extremely low.

We were sufficiently intrigued by the Verion to address some wide-eyed questions to its designer, Mitch Cotter, whose reply is reproduced here, making further technical comments unnecessary.

There remains the sonic performance of the Yerion to be discussed. It must be remembered that a chain is only as strong as its weakest link, so the sound you'll hear from the Verion can't possibly be better than that of the preamp you plug it into. To our ears, this transformer adds nothing to and subtracts nothing from the sound of the signal it passes.

Inserting it between the EMT and the Paragon, for example, and compensating for the difference in signal level (you can do this with the Paragon on account of its fairly high gain and adjustable input level) results in a change in background hash only, without any change in the actual sound. But careful-hash can be easily interpreted as "more air" or as better high-frequency response. It's our impression that a quieter background nearly always creates a more neutral, and to some people less glamorous, effect.

Of course, the Paragon isn't our reference preamp, and we'd much rather A-B the Verion plus-A3-system against the D5 system in the new Mark Levinson JC-2, or Verion-plus-mag phono against the MC-1 stage in the Rappaport PRE-1A, in order to resolve the basic issue of head amps versus transformers. That isn't as easy as it seems, however. It's impossible to plug circuit modules into and out of the JC-2 quickly: as for the MC-1, we believe it's slightly better than the mag-phono stage of the PRE IA, so it would be to some extent an apples and-oranges comparison. Suffice it to say, therefore, that the Verion is the best phono cartridge transformer known to us and the simplest way to add truly superior MC capability to your preamp.

Yamaha C-2

For manufacturer, price and other particulars, see original review in Part I.

Since the C-2 has a flat-gain MC pre preamp in tandem with its equalized phono stage, you wouldn't expect its basic sound quality to change a great deal in the MC position. It doesn't.

The high-frequency transients remain aggressive as hell, making the numerous attractions of this beautifully packaged unit quite irrelevant.

Yamaha CA-1000

For manufacturer, price and other particulars, see original review in Part I.

To the best of our knowledge, the MC amplifier chip in this unit is the same as in the C-2, and so is its position in the circuit. So our previous assessment of the CA-1000 was unlikely to be upgraded. If anything, testing the preamp section of this integrated amplifier with highly revealing moving-coil cartridges has lowered our opinion of it by half a notch or so.

Once an integrated amplifier, always an integrated amplifier.

Recommendations Without abandoning our search for still better pre-amplifiers, which from now on will be tested one by one as they come in, we're ready to present the overall conclusions of our two part survey.

Best sound with either magnetic or moving coil cartridges, regardless of all other considerations: Mark Levinson JC-2, serial number 2148 or higher.

Alternate choice (in view of the exorbitant price of the above): Rappaport PRE-1 or PRE 1A/PS-1/MC-1, depending on your phono needs.

Best sound per dollar (mag phono only): Advent Model 300.

Best add-on device for moving-coil capability: Verion MK1.

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Moving Coil vs. Moving Field, Transformer vs. Head Amp

Editor's Note: One of the leading experts of our acquaintance on the subject of extracting information from a record groove (not to mention 57 other subjects) is Mitch Cotter. When we asked him why on earth he bothered to design an ultra-sophisticated transformer when head amps are getting so good, he sent us the following reply, which includes the best argument we've seen so far in favor of the moving-coil cartridge.

The Audio Critic:

There occurs the thought that what is probably the most important aspect of my interest in moving coil pickups is not clear in the fact of the trans former that I have designed for them.

Why attend upon the problem? Since the electrons that flow as the output signal care not a whit about the nature of the transduction that produces them, what is there about the difference between moving coils and the others that compels me? The answer rests largely upon a little-discussed but important process occurring in playing a record. It is related to friction. The same frictional force that causes the well-known inward skating force in offset arms is due to a significant drag on the stylus, pulling the stylus cantilever out of the pickup in the direction of the motion of the surface of the record. The average force is about a third of the vertical tracking force.

This force is not constant but rather varies with the recorded signal. In fact this variation is not like the signal but is a highly distorted form of the groove modulation. This varying force causes what has been called "needle drag distortion." This distorted force can cause distorted output in two ways. First, if the stylus can move appreciably axially (down the record groove path), then the position of the stylus is not steady but is modulated by the signal in this distorted way and causes a self-FM or a time smearing of the reproduced sound.

Whatever transducer might be used, if its stylus so moves then the sound is smeared. Secondly, even if the axial motion is minimal, the transducer sys tem (pickup) may produce some electrical output from this needle drag force.

If this occurs even to a small extent, then a serious aural flaw enters, since these FM-like effects are far more objectionable than non-time-dispersive distortions. This is so even for slight amounts of these effects.

It is worth noting that in fact all the serious distortions in phonograph play back are of time-dispersive character.

Tracking error, both the vertical and lateral kinds, cause a similar effect.

The signal FMs itself as a result of the back-and-forth component of motion if the stylus does not move in the same plane as the cutting stylus. Tracking distortion similarly arises from the finite curvature of the playback stylus contact region on the surface of the groove, causing the region to move for ward on the uphill portions and back ward on the downhill portions of the modulated groove. The time-smearing character of all these disturbances is what gives the all-too-usual phonograph sound, which is audible even over limited frequency range systems. In that respect it acts somewhat more like flutter than the usual non-time-dispersive distortions.

To return to the moving-coil pick ups and my reasons-it should be said that all present examples share in having very rigid, wire axial supports, as opposed to the rubber-tire suspensions of many other types of pickups. More importantly, in the MC pickups the coil moves in a constant magnetic field. All magnetic pickups work by having the field vary in a coil of wire.

In the MC types the coil moves to do this. In the others the coil is stationary and the field is varied. All the others, regardless of the cute names to describe the device, vary the field in the magnetic path through a fixed coil of wire.

We can see then two distinct types:

the moving coils and the moving fields.

There is a very important difference between them, however. The moving coil is inherently insensitive to axial force output effects, whereas the moving field types all are inherently rather sensitive in this way. The greater clarity of sound for which knowing audiophiles have pursued the MC types arises very much from this aspect of the difference. This difference is innate and will persist as further developments push criteria higher. A phonograph record need not sound poorer than tape-in fact it can sound better.

There stood a barrier to realizing this promise, and it was the interface between the inherently low voltage (but high current) property of the MC pick ups and the higher impedance required for the best signal-to-noise ratio from pickup preamps. Present-day MC pick ups are actually possessed of higher S/N than are the other types. The ad vantage is typically about 10 to 20 dB.

Head amps cannot achieve that promise.

Gain does not accomplish the full S/N unless the amplifier has noise below that of the device to be amplified. The only way possible, and the best way ultimately, is to transform the pickup's energy to an optimum impedance and then use it in the standard phono preamp, which should then give better signal-to-noise ratio than when used with the moving-field pickups in common use today.

I consider it essential for clarity in record reproduction today to use a moving-coil type of pickup. The full signal-to-noise ratio requires a trans former that does not add losses or re strict the bandwidth, and those problems are the challenge that I feel I have been able to meet.

Further, the reduction of the vertical and lateral tracking error is quite as important in order to appreciate the dynamic range possible, since it then becomes acceptable to listen to the full, realistic loudness of the recorded music.

I feel strongly that the long neglect of these interrelated factors has dulled the awareness of even the devoted as to just how terrific the quality of the phono graph disc is in a very large number of cases. In fact it will be surprising to many that so many discs are that good.

That is certainly a very useful thing to most, since there exists such a wealth of recorded music that is not as lost as may have seemed.

Thank you for your interest in my views and this opportunity to air them.

Very truly yours, Mitchell A. Cotter Verion Audio Inc.

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[adapted from TAC, Vol.1, No.2]

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Also see:

A Comparative Survey of Power Amplifiers: Part 1

Various audio and high-fidelity magazines