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Review and Measurements of eXemplar Exception Phono Amp

anmpr1

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#61
In the early days of Lp, they all sounded different because each record company was using a different equalization scheme. I recall an early McIntosh preamp with a dozen or so phono EQ combinations; at least one of the hi-fi magazines published EQ settings with their record reviews, so you would know how to listen properly. Most people likely didn't bother with these sorts of adjustments. By the late '50s EQ was supposed to have been sorted out, but then you had 'innovations' such as Dynagroove. Progress, LOL.

Other problems: by the late '30s an analysis of lateral tracking error (offset/overhang values for minimizing weighted error) had been completed (first by Erik Lofgren, then worked out by others--see the excellent paper by Graeme Dennes on the subject, available on line using his name search), but none of this was really well known until the latter '60s and '70s. Probably due to the introduction of new and improved quality records (direct to disk), advanced styli shape that tracked inner grooves as well as outer, and generally better tonearm/record players. Cartridges improved in areas such as tracking, but sonically not as much as one might at first think. Even a design from the '60s, the Denon 103, sounds remarkable, today.

By the early '70s, phono overload, TDH and IM, channel balance, were routinely measured by reviewers, however many phono preamps that measured well were not judged to 'sound' that good, by others. Was this wishful thinking coupled to audio cultism? Or was there something to it? New measurement protocols were developed and put forth as explanations of this sort of thing. Tom Holman (cartridge inductance interaction), Alvin Foster (matched phono clipping levels), Matti Otala ('sign square' distortion test for TIM), and so on. Bob Carver once designed the 'phono 2' input of one of his Carver preamps using an old Audio Research SP-3a (evidently the same nulling protocol he used to model a Levinson ML-2 amplifier, and, at another time, a Conrad Johnson tube amp). In spite of all the time, effort, R&D, as far as I know no correlation has ever been found between either routine or esoteric measurements and 'subjective' impressions--at least once basic minimums for FR and distortion have been reached. Distortion in Lp playing is, of course, magnitudes higher than anything digital, so one could always assume that what some people like are different types of distortion.

FWIW, for my part, when I use phono, the biggest things I notice are hum and hiss, the first which can usually be effectively minimized, and the latter masked by vinyl noise and the musical program. Tubes or SS? One of my best 'sounding' (i.e., subjectively low noise) phono preamps is hand built using a JFET input followed by 12AY7 tubes. I don't think I can reliably tell the difference between it, and a couple of other solid state phono preamps I have. In one of my drawers, I have a hybrid tube/op amp Bellari phono box, that I believe is noticeable, although I haven't tried to do any AB. It is certainly more noisy than the others. To its credit it has a sub sonic filter. So it's got that going for it. For phono, you really need a subsonic filter, a balance control, and mono/L-R switch on your preamp. These used to be common place, but now are rare.

In any case, the biggest determinant to sound quality is the record itself, both recording technique, and the plastic physical surface. Somewhere in my collection I have (I think) a Stan Getz record, supposed to have been engineered using a Mark Levinson modified Studer A80 and his LNP preamp as a 'console'. The sound is flat and dull, but the performance is good. A couple of Direct to Discs (Doug Sax Sheffields, and AT Umbrella recordings) have superb sonics, while the progams themselves are only average. What good is that?

I have a lot of records, because I'm older, and kept them in good shape. I play them a lot. Why anyone today would want to get involved in records, at least from a sonic standpoint, is something I really don't understand. Sorry this went on for so long.
 
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#62
7 K? This is slumming in the world of analog phono. An eponymous company in Boulder CO makes a phono stage selling for fifty large. In truth, these things have nothing to do with measurements. It's all about 'front to back depth", "mid-range bloom", and made up stuff like "pace". That is, stuff no one can pin down. Audio neurosis at its finest. The only thing more idiotic is the world of high end audio cables. Phono science used to be respectable: analysis of the geometry of tracking error, mechanical resonances, and stylus shapes. But all that's been figured out, long ago. As near as I can tell, it all started to go south when Yoshiaki Sugano figured out that he could sell high priced jewelry to men, by enclosing his hand built cartridges in semi-precious stones and exotic wood.
As far as I know, that Boulder phono preamp actually measured incredibly well (Stereophile measured it). 40-50,000 dollars is still outrageous, obviously, but at least it wasn't broken like many expensive products. Just for fun, first read Michael Fremer's rave review of the Zanden 5000 Mk.IV CD player, where he essentially calls it the best CD player he had ever heard, actually the only one he could stand to listen to, and then afterwards read John Atkinson's measurements and subsequent listening test.
Nevertheless, Musical Fidelity made a $1000 phono preamp that measures incredibly well as well, and NAD made a phono preamp (which I currently have) that also measures incredibly well and only costs $150-$200. The latter, PP-4, was measured in Stereophile in its former incarnation, PP-3.
So, performance in a phono preamp similar or close to that of the Boulder doesn't have to cost a fortune.
 
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