Conrad-Johnson PV11 preamplifier
Like most audiophiles, I eventually discovered just how difficult it is to find a preamp that sounds good and still leaves some of one's audio budget for other parts of the system. Designing and building a first-rate preamp must not be an easy matter, or there'd be more of them around. For the past several years I've been using a Conrad-Johnson PV5 and have felt no great urge to replace it, reading with a certain smugness in JA's review of the PV9 (Vol.12 No.5) about the fellow who swapped his PV5 for a Class A phono stage/passive controller combination that was ostensibly more accurate, but somehow he wasn't enjoying listening to music as much as he had with the PV5!
As the PV11 is a lineal descendant of the PV5, I was particularly excited to get it as one of my first pieces of equipment to review. Does it retain the musicality of the PV5 while offering lower levels of coloration? Then there's the Threshold FET nine/e that I also review this month, junior sibling of the FET ten/e, a solid-state preamp that has earned a rave review from noted tubeophile Dick Olsher (Vol.14 No.3). And what about the Audio Research SP9 Mk.II, sent along by Thomas J. Norton to provide a reference? Does this hybrid design combine the best of vacuum tube and solid-state technologies? Can a tissue be soft and strong? Will Spenser ever meet Kinsey Millhone?
The Conrad-Johnson PV11: $1895
Conrad-Johnson advertises the PV11 and the MV52, its companion power amp, as "classics revisited." Indeed, there are obvious similarities to previous C-J models: the brushed-gold front panel, reassuringly large knobs, two sets of main outputs, the much-criticized tape-monitor arrangements (I've never had a problem with this, but it is possible to induce potentially speaker-damaging positive feedback with the wrong combination of switch settings), and phono inputs optimized for moving-magnet rather than moving-coil. The tape outputs are not buffered, so, for optimal performance, any tape decks connected to these outputs should be turned on even when you're listening to another source; alternatively, the plugs should not be connected to the tape-out jacks except when making a recording. In design, C-J seems to be moving toward a less-is-more philosophy: there is no global negative feedback (the PV5 had about 30dB feedback), and the line stage now consists of one rather than two gain stages. Since the line stage inverts absolute polarity, speaker connections should be reversed (assuming that the amp is non-inverting).
In comparing the PV11 with the PV5 and the Audio Research SP9 Mk.II, all of which are non-inverting, I took care to make the speaker connections so that the system as a whole would be non-inverting. (The original Quads are polarity-inverting themselves; ie, what's marked positive on the Quads would be marked negative on other speakers. In this case, two wrongs do make a right.)
The balance control of the PV11 is a multiple-position switch rather than a potentiometer; resistors are switched in to provide a maximum of 12dB lateral shift, and they are out of the circuit in the neutral position, thus removing the temptation to do a balance-and-mode bypass modification. (Still, I do wonder if bypassing the mode and balance switches could provide at least half a smidgen of improvement.) Conrad-Johnson has eliminated the use of electrolytic capacitors in their latest preamp designs; all capacitors, including the ones in the power supply, are the same high-quality polystyrenes and polypropylenes made to their specifications.
Quality of construction is to a higher standard than in earlier models (switches and the volume-control pot seem smoother than on the PV5), and the overall look is one of restrained elegance.
At the 1990 Stereophile Writers' Conference, someone (PWM or LA, I think) made the point that audiophiles and audio writers have a tendency to use hyperbole in describing sonic differences between components, so that any noticeable difference is described as "huge." Meridian's Bob Stuart, in his Vol.14 No.9 interview with Bob Harley, has suggested that it is almost a law of human nature to emphasize the importance of small differences. Taking into account both points, I can say that the sonic differences among the auditioned preamps were "huge"; alternatively, that the differences were small but important, perhaps because they were small.
The PV11 quickly impressed me as being distinctly superior to my somewhat-modified PV5: less colored, tidier at the frequency extremes (sweeter highs, but instruments with a lot of overtones retain their characters; less bloated bass), a more layered definition of depth, more precise focus, greater sense of ambience, and, when the music featured these qualities, an exceptional sense of rhythm and drive. In fact, it was this "rhythmic" quality, allowing one to more easily follow small variations in tempo, that I found to be the PV11's outstanding positive attribute, present in both LP and CD reproduction, an attribute not quite matched by any of the other preamps (footnote 1).
Listening to something like "Under the Sea" (from The Little Mermaid, Disney CD-018), Paul Simon's "Kodachrome" (There Goes Rhymin' Simon, Columbia XC 32280, LP), or Dick Hyman playing Fats Waller's "Viper's Rag" (Reference Recordings RR-33DCD), my toe (which does a lot of listening) could not keep from tapping. The rubato and subtle dynamic variations in the Bolet/Chailly Grieg Piano Concerto (CD, London 417 112-2) were more apparent than I've heard before, and, again, better than with any of the other preamps in the system. Voices had a rounded, "present" quality; listening to Pavarotti's Carnegie Hall recital (CD, London 421 526-2) in the dark made me wonder if Luciano had somehow teleported himself into my listening room. (Come to think of it, the floor did creak in a mysterious manner during "Pietè Signore.")
Footnote 1: I'm tempted to speculate that this sense of rhythm/pace is due to the lack of negative feedback (Martin Colloms noted a similar characteristic in his Vol.13 No.12 review of C-J's zero-negative-feedback solid-state preamp, the PF1), but the SP9 Mk.II, which has about 20dB of feedback, was nearly as good in this department.