PS Audio 4.6 preamplifier Page 2

Ultimately I chose a vintage, broken-in, but otherwise little used (about 50 hours) Dynavector 17D. It was chosen because it was readily available, was at one time a state-of-the-art contender (it is no longer, of course, but remains fully competitive with any low-output moving-coil likely to be used with the 4.6), and, most important, it does not have a rising high-end response (footnote 1). My intent was to use the 17D and, if necessary, move on to the MC-One. Time did not permit the latter, but neither did I ultimately feel it to be necessary.

And it did take time to evaluate the 4.6. What we have here is not one preamp but twelve. How's that again? Count 'em: high-level, moving-magnet, moving-coil inputs make three; two different power supplies (the standard and the optional M-500), sampled with all three of those inputs, makes six. Normal and bypass modes with all of these possible combinations makes twelve. Whew! To keep this evaluation from running all year, I concentrated on four possible permutations: high- and low-level phono stages, and normal and M-500 supplies. The high-level inputs were sampled with CD (using primarily the CAL Audio Aria player), but this was not as extended as the phono stage evaluation. As to the bypass modes, these were also sampled where system gain permitted (as previously noted).

Auditioned through the moving-magnet input (using the MCX), the PS Audio 4.6 gave more than a hint of high-end performance. Recordings which were well-balanced, and not recorded from an overly close perspective, were reproduced naturally, with well-rendered (but not exaggerated) detail, good transparency and soundstaging, and a tight, clean low end. I listened to a number of Opus 3 recordings through the 4.6; although there are exceptions, these recordings are, as a group, as well recorded a spatial perspective (not to mention their clean, transparent overall sound) as any I have come across. Ojebokoren/Cyndee Peters (77-04) had a good separation of choral detail.

Depth was notable, though not dramatic. Imaging was excellent. The top end was clean though a bit short of transparency and "air." Music from Bofors (8101) revealed the same slight lack of openness, yet hard transients were well handled. Solo voice was neutral. The same could be said for the more familiar River Road (8017), a recording with a more up-front perspective than either of the above. Overall sound quality on the Opus 3 recordings could be fairly described as detailed yet natural, with well-defined imaging, depth, and overall focus, and no tendency to over-etch or exaggerate in any fashion.

My listening sessions with the PS were not restricted to Opus 3 recordings, of course. With recordings having more robust high-frequency content, the 4.6 did reveal a trace of brightness, a slightly "electronic" tinge. But it was well-controlled and not a serious flaw, certainly not in a "budget" preamp, and my other impressions continued unchanged. This is an exceptional performer in its price range, at least through the moving-magnet input. Only in comparison with a far more expensive preamp, the Klyne SK-5A (a fivefold increase in price), did the 4.6 reveal its limitations. To say that the PS failed to duplicate the depth, air, and overall focus and natural detailing of the Klyne is perhaps to state the obvious. I'm continually hopeful that some day a brilliant designer will produce that inexpensive preamp (or power amp/loudspeaker/whatever) that makes more expensive designs irrelevant, substituting sheer engineering skill for dollars. The 4.6 is not quite that preamp, but its moving-magnet stage comes close enough to at least suggest that it might some day be possible.

But what about the moving-coil input? Since low-output moving-coil pickups appear to dominate the high-end scene, this is a matter of some importance. For starters, the moving-coil input of the 4.6 is, as you might expect, somewhat noisier than the moving-magnet. I never found that noise obtrusive, but with the volume set for moderately high (though not extremely high) listening levels, hiss was just audible at a listening position about 10!0 from the loudspeakers, the system otherwise at idle (no playback in progress). Hum was inaudible under the same conditions. The hiss was never audible in actual playback—it was masked by vinyl noise. Variations in system and listener sensitivity will render it more or less obvious; many very pricey preamps will do little better in this regard, and I'm not talking here about the type of thermal noise tolerated by some listeners in driving a tube-preamp moving-magnet input with a low-output moving-coil!

The moving-coil stage of the PS 4.6, using the standard power supply, proved something of a sonic disappointment. There were no real surprises here; using the Dynavector 17D, the nearly realized high-end ambitions of the MCX/moving-magnet stage dissolved into a merely competent overall sound. The Dynavector pickup inherently has more sparkle and detail than the MCX (the latter counters with a more relaxed, sweeter, slightly warmer sound, less cool and analytical). Transparency with the 17D into the 4.6's low-level input (set for a 100 ohm load) seemed limited; perspectives were flattened, although some depth remained. Those Opus 3 recordings were still clean and listenable, but were a bit forward and lacking in openness. The sound was not at all irritating, just uninvolving; my notes refer to the sound as "OK," but not much better. Comparisons with the Klyne took little time here; with the moving-magnet input and Grado the two preamps had been, sonically, far closer. Switching the 17D from the Klyne to the 4.6 on Star of Wonder (Reference Recordings RR-21) resulted in a major loss of air, three-dimensionality, and transparency. I had to look to be certain I was listening to the same side of the recording (I was).

My definite recommendation for the 4.6, using its standard power supply, would be to stick with the moving-magnet input and a good high-output cartridge. My experiences using the Grado MCX indicate that such a combination is distinctly more satisfying than the combination of the (spectrally) neutral 17D into the 4.6's moving-coil input. I could live quite happily with the former combination over an extended period, but not with the latter. While a moving-coil with a rising high end might compensate to some extent for the slightly veiled sound I experienced using the PS's moving-coil input with a relatively flat cartridge, I prefer to avoid known colorations where possible (there are enough unknown colorations to go around). If you already own a good low-output moving-coil cartridge, you may find the low-level input of the 4.6 acceptable. But other than a lack of irritating qualities, I did not find it exceptional.

Adding the power supply
But stop the presses! There's more! We now have the "other" PS 4.6, the one with the optional M-500 power supply. True, with this combination we're no longer talking moderately priced preamps; the $495 cost of the M-500 runs the total up to $1094. (I know, I know—that doesn't add up. The difference is a $50 trade-in allowance for the basic HCPS.) And at that price you can consider PS's own upmarket 5.5 preamp (well, nearly—the 5.5 is $1195), which itself can be used with the M-500, which in turn will run it up well above the price of the 4.6/M-500—I surrender, Paul. I can't comment on the 5.5, not having a sample on hand, but that's an option I would at least investigate before running out to buy an M-500 to use with the 4.6.

With that caveat, however, I must say that the 4.6/M-500 combo was a significant improvement over the 4.6 alone using the moving-coil input. Focus tightened up. Transparency, air, and overall openness were now excellent. Soundstaging, including overall depth, was very well rendered. Overall sound was consistently lean, taut, and detailed—probably both its greatest strengths and its most potentially controversial attributes. It was never hard, harsh, or in any way irritating, at least to this reviewer, but some will find it somewhat lacking in warmth, and very subtly "clinical." But those are also characteristics of the 17D, and possibly (though my assessment of the amplifier is as yet incomplete) of the 200Cx as well. The conclusion is clear: the 4.6/M-500 is capable of excellent moving-coil reproduction, but you should choose your associated equipment carefully.

I haven't yet discussed the sound of CD into the high-level stages of the 4.6. In a few words, it was neutral and open, leaning more toward the sweet than the punchy and dynamic. While it lacked the palpable sock and drive of, say, the Sumo Athena, it made up for it in improved depth and dimensionality. Inner detail was plentiful but never exaggerated on well-recorded program material. But good as it was, the M-500 power supply added significantly to the overall performance. Midrange and highs were more open; individual voices in choral works were better defined, instrumental separation was enhanced, and dynamics improved noticeably. Bass, already very good, was tightened. The improvement was not as significant as with the moving-coil input, but was definitely worthwhile.

My experiences in using the M-500 with the moving-magnet stage of the 4.6 were less conclusive. With certain combinations of associated equipment, addition of the M-500 made the sound more incisive. Bass was stronger but, curiously, less taut than with the standard supply, although the differences weren't all that pronounced. With at least one setup—the PS 200Cx driving the Epos 14s—I actually preferred the standard power supply with the Grado MCX as the program source. I have no ready explanation for this; given the improvements noted with the M-500 when using the high-level inputs and the moving-coil stages, I have to conclude that the PS is more accurate with the gigando power supply. But there will be situations in which the basic supply may be preferred.

Even with the standard power supply, I was very impressed with the 4.6. Used with either a high-output cartridge or CD, it performed flawlessly. More to the point, it didn't keep reminding me that I was listening to a budget preamplifier. Add the M-500 power supply (which you can always do at a later date), and the clear improvements in moving-coil and CD performance make the PS an all-around excellent performer. You'll find competitive preamps which sound different, to be sure—the 4.6, even with its trick supply, is unlikely to warm the cockles of a tube-lover's heart. But it will take a significant jump in price—to the $2000 range and more—to clearly improve on its performance. I strongly recommend you give it a listen.

Footnote 1: While the high-end response of any cartridge will measure differently with different test records, I have never seen a 17D measure with a rising high end, either my own (and a previous sample measured by me, both with the CBS STR-100 test record) or others I have seen reviewed with other test records.
PS Audio
4826 Sterling Drive
Boulder, CO 80301
(720) 406-8946

Bill Leebens's picture