March 2002Conrad-Johnson PV14LS Preamplifier
by Tom Lyle
Design and features
The PV14LS is a vacuum-tube line-stage preamplifier with a zero-feedback circuit based on a single-stage triode amplifier using one 6C4 miniature tube per channel. A direct buffer stage provides a low output impedance, making the PV14LS capable of driving long interconnects and compatible with a wide range of power amplifiers. The zero-feedback design of the PV14LS, says C-J, avoids audible timing errors that occur in preamplifiers using loop feedback. Thus, "properly executed" zero-feedback circuits such as the one used in the PV14LS can "reproduce music with its astonishing dynamic range and all-important time and spatial relationships intact." C-J also stresses that their power-supply design is as important as the audio circuit. They employ discrete DC power-supply regulators to filter noise and fluctuations from the power line.
Internal component parts are, according to C-J, "of the highest quality." Polypropylene and polystyrene capacitors are used exclusively in the audio circuits and related power supplies. The volume control is a discrete switch-selected resistor array that is entirely designed and executed by C-J and ranges from 0 to 100 in approximately .7dB steps.
The PV14LS has seven gold-plated single-ended inputs on its rear panel. Two of these are part of the two tape loops, one labeled EPL1, for external processor loop 1, and the other THTR/EPL2, or theater/external processor loop 2. The first is meant for connection to a tape recorder or an external processor such as an equalizer (the equalizer is C-J's suggestion -- not mine!). The second is for a surround-sound processor, and when this input is selected, the level controls are set to unity gain. Level and balance are then controlled via the surround-sound processor, not the PV14LS.
The remote control can direct all operations of the PV14LS, but only from the remote control can you adjust the balance of the preamp. Controlling its functions via the small wand quickly became intuitive, although I mainly used only the volume and mute functions.
The units standby mode prevented any noise from being transferred to the speakers even when the power amp was turned on first. A red LED glows below the power switch indicating that the unit is connected to AC and its control circuits are powered. When the power switch is activated, this LED flashes, and for about 90 seconds the units output is muted. As long as the PV14LS remains connected to the AC, the last used volume and input settings are recalled when the unit is powered up again.
The PV14LS measures 14 3/8"D x 19"W x 3 3/8"H and weighs 14 pounds. The power cord is connected via an IEC jack, and I connected this power cord to a PS Audio Power Plant P300 AC regenerator. There was a noticeable improvement in sound versus a direct connection to the wall. I used a number of MultiWave waveforms and settled on PS Audios favorite, the first in the series of waveforms.
Use and sound
Breaking in the PV14LS was no big deal. Maybe its sound was not as robust until I put about 50 hours on the tubes and other circuit parts. But after this relatively short conditioning period, I felt it was safe to do some serious listening.
The first thing I noticed about the PV14LS had nothing to do with the sound quality: the C-J is a remote-controlled unit and my reference preamp is not. Being able to change the volume from my listening seat was awfully convenient, not to mention the ability to mute the system when spinning LPs. The only inconvenience (Ill call it that even though I have a tough time using that term when describing a remote) was that I couldn't change the volume of the preamp when the mute function was engaged. When defeating the mute, the PV14LS reverts to the last volume setting.
The PV14LS has excellent resolving power and at the same time the ability to draw the listener into the music. This involvement and lucidity were just about its best qualities, and they enabled me to "look into" each recording that passed through it. Of course, this was dependent on the source material, and poor recordings were revealed as such. Still, substandard recordings were sweetened a bit by passing through the PV14LS, which made them more tolerable. This slightly sweetened sound on good recordings manifested itself as a euphonic tinge that added a touch of both seductiveness and realism to almost every recording of an acoustic instrument. And although you might think that the PV14LS's character would decrease the apparent transparency of the unit, it really didnt.
Danilo Perezs Motherland [Verve 314 543 904-2] is a great CD. I was lucky enough to catch Perez in concert with most of the personnel on this album, and a great show it was. The music is a combination of jazz, Afro-Cuban, and just about every South American countrys take on jazz or funk. But this description doesnt do justice to the sound on Motherland. It's an excellent recording, mastered by none other than Doug Sax. Perezs piano and especially Chris Potters sax took on a realism that was extraordinary. There was a very slight timing loss due to the PV14LSs slight rounding off of the leading edge of the transients, and as a result the "crack" of the drums was slightly reduced in impact. I must emphasize that this loss of transient response was very slight, so this recording still was able to show off the PV14LSs strengths.
The PV14LS is a soundstaging champ. There's no doubt to me that the soundstage on Motherland is a studio concoction, but it hardly matters. Perezs piano was spread across the front of the soundstage, with the drums stretched out behind it, and the rest of the bands locations were easy to identify. Presence and sweetness replaced the slight loss of detail and were able to transform my listening room to a portal into the recording session. And the abundance of metal percussion on the disc demonstrated that the PV14LSs euphonic character did not come at the expense of treble extension. Percussion sparkled throughout the soundstage, but the treble was never fatiguing, which is perhaps to be expected of a tubed component, but it also didnt sound as if the PV14LS editorialized the program material other than to amend it with a bit of refinement.
But its the midrange that made me understand the PV14LS's character fully. On Nothingness [Atlantic 83391-2], Olu Dara's slightly raspy voice and expressive cornet playing front his blues/funk/jazz amalgam. With the PV14LS in use, there was in no way an excess of tube bloom that veiled the material. In addition, there was none of the lower-midrange boost that sometimes occurs with inexpensive tube components and would make Dara's voice sound chesty. The PV14LS let the recording determine the timbre of the midrange. Its deviation from absolute transparency was not patently noticeable until I removed the PV14LS from the system -- and even then it didnt sound as if a veil was lifted from the recording. It was more as if there was a slight increase in focus. Other preamps more straightforward sound might make it seem as if you are brought just a little closer to the original recording, while the PV14LS's character in the midrange was more of a slightly additive glow.
The PV14LSs bass was not what I expected. The PV12, which I used to own, had bass that was a major shortcoming, while the PV14LS sounded as if there was a complete revision in its sonic design in this area. Bass was solid, pitch-stable and tight, although comparing it to the absolute, which is live music, or at the very least the absolute best Ive heard in my listening room, the low end was a bit overripe. But I must emphasize "a bit." I had to really study the bass on quite a few recordings until I could put my finger on exactly what the idiosyncrasies were. It was more of a perception of relative volume, I guess, where some of the bass frequencies were just slightly increased in volume.
Finally, I think its important to note that the PV14LS's operation was dead quiet. This line-stage preamplifier contributed no noise that could be heard unless there was no music playing and you stood right next to the speakers. When playing records, I found the records surface noise and the phono preamplifier background hiss were much higher in volume than the slight hiss emanating from the speakers when there was no program material passing through them.
Ive been partial to C-J preamps since the first half of the 1990s, when I owned a full-function PV11. Later in the decade, I upgraded to a PV12, and it wasnt until early 2000 that I switched allegiances and upgraded to an Audible Illusions Modulus 3a with its integrated Gold MC phono board. The Audible Illusions Modulus 3a has been my reference preamp for a long enough time for me to be very familiar with its sound -- or lack thereof. Its transparency is unmatched by every other tube preamp Ive heard in its price range. Its highs are natural, if such is what is presented to it by the source component. Its mids are natural for the same reason, and its bass seems unlimited in scope in both depth and tautness -- again, depending on the source component and material.
And lest this review turn into an Audible Illusions review, Ill just state that the PV14LS was able to go up against it without embarrassing itself. I preferred the more open sound of the Modulus 3a. Some might prefer the PV14LS's slightly euphonic sound. Some system matching might also be necessary, for the PV14LS might be a better match with more bright or forward-sounding amplification, source components, listening rooms, or speakers. There are differences between the units, but Im not sure there would be universal agreement on which one is superior.
The Conrad-Johnson PV14LS stirred up memories of the days when I owned Conrad-Johnson preamps. The older models were a perfect match for the solid-state amplifiers that I used in my system at the time, many of which had a more forward and detailed presentation. But now that I have a more transparent system, the C-J PV11's and PV12's excessively smooth sound might be more of a disadvantage. But the new PV14LS has very little of the old C-J sound. Yes, it has a character that sweetens the overall timbre a bit, but this is in no way an obstacle to building a transparent-sounding system.
But more than this, for a relatively affordable price, the Conrad-Johnson PV14LS performs at a level that starts to enter into the class of very high-quality, and pricey, components. Of course, there are better preamps available, but you have to consider the small gains in sound quality that you might expect from a different preamplifier versus the amount of money you are going to have to spend to get it. This is because any preamp that sounds substantially better will most likely come with a much higher price tag -- and at the same time will undoubtedly invoke the law of diminishing returns. And instead, you could have a PV14LS, which was a pleasure to use and listen to.
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