Tube Preamp Reviews

In appearance Conrad-Johnson's PV4 is distinctly plain: a basic black and silver box with a few simple knobs and buttons. The controls are logically laid out, clearly labeled, and work properly. The two channels track well through the volume control, maintaining balance; pushbuttons and control knobs have a smooth, solid feel (except for the noises audible through the system when switching inputs). Don't forget the turn-on and turn-off thumps mentioned above; the PV4 is the only one of the preamps I review in this issue—the others are the Audible Illusions Modulus ($450) and the Counterpoint SA-7 ($595)—that lacks a mute switch.

Sound Quality
The most noticeable flaw in the PV4 is a moderate subjective rolloff in the high frequencies. If a compromise has to be made somewhere, this is a reasonable choice. In view of the high-frequency performance of speakers and amplifiers with which the PV4 price range will probably be used, it may even be a blessing in disguise. Bass is good, though not outstanding. Weight and authority in the low bass are only fair, and the bottom octave has a one-note sound making deep basslines hard to follow. However, this is only obvious on a speaker and amplifier combination capable of reproducing the bottom octave with reasonable accuracy and authority. With most lesser speaker/amplifier combinations, more typical of what one might use with a sub-$500 preamp, the PV4 is capable of taxing their bass extension limitations, and then some.

Soundstage width is good, though somewhat lacking in focus. The PV4 also seems to reduce dynamic range just a bit. But these are not the kinds of flaws that make a component sound bad; rather, they merely prevent it from sounding great. On the plus side, the PV4 is clean, open sounding, lucid, has excellent detail, and has an outstanding ability to convey the feeling of a live performance. Inner detail is amazing for a component of this price. Though the PV4 certainly doesn't rival C-J's Premier 3, it is relatively easy to distinguish individual voices in choral works or to count the number of horns playing in a fanfare.

The overall tonal balance is good, save for the HF rolloff and a bit of warmth in the lower midrange. The PV4's ability to convey contrasts ofinstrumental timbre exceeds most units I've heard at twice its price. The relative tonal differences between similar-sounding instruments, such as oboe and English horn, are conveyed with exemplary accuracy. This quality, together with the PV4's excellent detail, causes one to forgive its mild midrange colorations.

The PV4 paints with a broad brush; both instruments and vocalists often seem overly wide. Depth is fair, but the PV4 does not present the marvelous, three-dimensional soundstage achieved by the most expensive tube units. Ambience is not conveyed well, and it is difficult to gauge the size of room in which a recording was made. Everything sounds as if it were recorded in a large, somewhat dead hall.

The most impressive characteristic of the PV4, in view of its price, was its ability to sound just plain musical, without excessive coloration or loss of detail. Other budget preamps manage to sound "musical," but their musicality generally is obtained by glossing over details and adding coloration. The essential musicality of the PV4 makes it very easy to live with, even in a state-of-the-art system, which is quite an achievement for a low-priced unit.

Interconnects
Since tube preamps have higher output impedance than most solid-state preamps, cable matching becomes fairly important. The PV4 was the least affected by the type ofinterconnect cable used, and had no trouble with higher capacitance cables. This is probably due to its significantly lower output impedance, which makes it less affected by the load it is driving. I found the PV4 to sound most neutral with both the Monster Reference cable and a high-capacitance prototype cable. The Straight Wire Premium, also a higher capacitance cable, worked well, producing a more detailed sound than the Monster cable, but accentuating the PV4's midrange warmth.

Conclusion
The PV4 was my favorite of these three preamps, not because of the greatness of its strengths but for the relatively minor and easily tolerable nature of its flaws. If this sounds like winning by default, remember that you're not going to get state-of-the-art for under $500. The biggest challenge the designer of a budget preamp faces is how to avoid making it sound terrible, not how to make the product sound marvelous. This is a goal the C-J team has accomplished very well.

Both the Conrad-Johnson PV4 and the Audible Illusions Modulus offer very good performance, and can be highly recommended in view of their prices. I suspect the choice between the two will depend greatly on the other equipment with which they will be used. The PV4 would seem the clear choice with speakers such as the Stax F81 or Quad ESL-57, which are capable of showing the PV4's ability to reveal detail and harmonic contrast, but not fully capable of utilizing the Modulus' dynamics and frequency extension.

The differences between the Modulus and PV4 also point out that though both products offer good value for money, neither approaches perfection. Before buying one of these low-priced units, potential purchasers should be aware that for under $500, a tube or solid-state preamp must incorporate some compromises. In my opinion, however, Conrad-Johnson has done an excellent job of compromising.