Conrad-Johnson PF-1 preamplifier

Cycles can be seen in the fortunes of companies. Likewise cycles can be seen in the performance of companies' products. A particular range will appear to have got it just right, whatever "it" is. The designer may have hit a winning streak and thus steal a lead over the competition. C-J set a new state-of-the-art preamp standard in the late 1980s with their Premier Seven, and some of that expertise and experience are beginning to pay off in the shape of new high-performance preamplifiers at realistic prices. Two important products have emerged from all this in C-J's moderately priced FET range, namely the PF-1 preamp and the matching MF-200 power amp. By audiophile standards, these are moderately priced at $1295 and $1995, respectively.

The one-box PF-1 has disc and line inputs, the latter rather sensitive for CD use, and while the disc input is rated as universal, there may be questions about its compatibility with some cartridges on grounds of input noise and input overload margin. On the face of it, the PF-1 does have sufficient gain for the direct connection of a moving-coil cartridge.

The PF-1 is of 19" rack width but is quite compact at 3.5" high. Finished in a pale-gold brushed alloy, the front panel is well-laid-out, with clear, unambiguous legends. From the left we have the input selector with a choice from phono, tuner, CD, and tapes 1 and 2. The source/tape monitor follows, then the mode switch, stereo/mono, etc. Add the stepped balance control, and the lineup is completed by the standard volume control. On the back, the mains cable is captive while the sockets are unbalanced phonos.

Technology
The PF-1 is based on FET circuits, the low-feedback design intended to capture some of the character of tube technology. One striking aspect of the PF-1 is the complete absence of electrolytic capacitors, either in the signal circuits or in the power supplies. This is in accordance with C-J's wholehearted belief in the superiority of plastic film capacitors in all applications.

The power supply begins with a primary regulator feeding three secondary regulators, one for each gain-stage block. Described as a zero-feedback design, this gain-stage block employs distortion-canceling techniques to help achieve satisfactory linearity. Operating as a low-impedance buffer with a voltage gain of 20dB, it is used in both the line amplifier and the output stage of the disc amplifier. Between the first disc stage and the latter comes the passive phono-equalization network. The phono input uses a J-FET in a single-ended configuration, and is non-inverting overall. All capacitors are polystyrene or polypropylene film; with the single-rail circuits used, capacitors are necessary to couple the stages.

Sound
First trials suggested something special from the PF-1; accordingly, I gave it a generous level of care and attention during auditioning, including the use of worthy ancillary equipment.

I began listening through the PF-1's phono input after suitable conditioning and adequate warmup. Within a context of some absolute references, I was not disappointed. Certainly the PF-1 was not as neutral and as uncolored as the finest, nor did it display the same level of focus, precision, and stability. However, it did offer a sound quality in one way that was right up with the very best, and which was promised by the zero voltage feedback circuitry. That quality is a sense of liveliness, presence, transient believability, and dynamic excitement—something that great audio is all about. As a rock fan would put it, the PF-1 sounds upbeat, with a great presentation of pace and rhythm. In fact, the more I became aware of this aspect of its reproduction, the more I saw it as a fundamental and necessary requirement. Returning to most other preamps gave the impression that they are slow and drowsy, diluting dynamic contrasts and returning a downbeat impression of rhythm. Make no mistake, the PF-1's phono stage is something of a reference in this area, and could well be bought for this alone.

Readers may recall several reviewers' similar reactions in the mid '80s to the Counterpoint SA7, a low-budget, zero-feedback tube design. I also recall remarking, when hearing the excellent bass performance of the Krell KSP-7B, that once you've lived with that kind of bass it's hard to give it up. This remark is equally true for the high level of pace and dynamics delivered by the PF-1. Such high performance is unexpected at this modest price level, and the overall performance is, in any case, difficult to fault; it does not let the side down.

Another strong quality of the PF-1's phono input was its ability to maintain high levels of detail regardless of the music's complexity. It consistently proved adept at revealing inner levels of orchestration with the full weight required for good counterpoint, and giving the feeling of many players working in concert on large orchestral pieces. Conversely, the sound was not excessively analytical in the sense that the performance was being unduly dissected. Throughout, I was aware of a unifying coherence to the presentation of all kinds of program.

The PF-1's phono stage was "boppy" and lively in the bass, tuneful and agile, if lacking the full weight, slam, and authority of the finest references. What also mattered was the evident ability of the PF-1's bass lines to keep excellent pace with the mid and treble. For want of a better comparison, the bass was more like that of a Roksan turntable than a SOTA.

The midrange was fascinating, as within its fairly close approach to neutrality there was also a hint of leanness and crispness, sufficient to align analog disc sound a little closer to the accepted sound of CD.

Dynamics were first-rate, the human voice sounding naturally expressive and allied to a strongly communicative import. "Hardness" in the accepted sense was absent—instead, singing voices sounded surprisingly real.

The treble sounded pure, with only the mildest loss of detail and transparency. Nonetheless, a good feeling of recorded atmosphere and air was presented in the treble, which also showed excellently controlled vocal sibilance and negligible grain or "edge."

Stereo images were presented with very good focus, good width, and fine depth. Recorded ambience was recovered well, and the general level of transparency approached audiophile levels. Well-worn LPs showed new levels of energy and detail, making the assessment of the PF-1 a continued pleasure.

If you think this all sounds too good to be true, you're right. Perversely, this C-J preamp did not maintain this exceptional standard when fed a CD diet (polarity-inverted, of course!). The presence of some moderate coloration gave a "harder," "darkened" sound; CD sources were not felt to be as well-balanced as the analog disc performance might lead you to suspect. It was as if a similar tonal flaw was present in both the PF-1 and CD, and was additive, whereas the analog source and RIAA equalizer lacked that flow, avoiding their sum rising above an audible threshold.

On CD, the PF-1 was a touch lightweight; comparison with a passive-controller connection showed this well. Nevertheless, much of the fundamental quality described earlier remained; if not, this assessment would be nonsense, as the analog disc signal did successfully pass through this very high line stage.

In absolute terms there was a loss of stereo focus and width, though what remained was still impressive, well beyond its price class. The sense of scale and of natural expressive dynamics was retained, and low-frequency sounds were lively and rhythmic, involving and interesting. Transparency was very good, sufficient for a strong impression of stereo depth and for the recovery of ample ambience and recorded acoustic.

Only the finest CD sources would begin to tax this line stage.

When the PF-1 was teamed with the MF-200, there was a clearly audible affinity—a level of compatibility where much of the PF-1's virtue was communicated to the speaker load. While the MF-200 was not so obviously an exceptional performer, the two products partnered each other well, making it hard to argue with the overall result, notwithstanding the PF-1's ability to reach even higher.

Conclusions
The fun really starts with the PF-1, which I'm sure has surprised C-J as much as it did me. Sure, it isn't perfect. Care needs to be taken with the phono input matching, and it's advisable to use a sweeter, more musical CD source, like a Meridian Bitstream player (or even C-J's own). When all was said and done, however, it was the dynamic, rhythmic quality of analog disc performance that I especially remembered, and which took the PF-1 right into top audiophile territory.

Its performance on other subjective grounds was sufficiently good so as not to prejudice this result; thus the PF-1 must be rated as an amazing hit. Its musicality reached far beyond its modest $1295 price-tag, though your dealer will have to earn his sales commission in terms of advice to attain the optimum result. The lab results helped define the operating limits while also showing that the unit was fundamentally accurate, particularly in terms of its RIAA equalization. Low-powered, it may be left permanently warmed up, always ready for immediate use. This convenience is complemented by the compact, well-screened, one-box construction—need I say more?

COMPANY INFO
Conrad-Johnson Design
12733 Merrilee Drive
Fairfax, VA 22031
(703) 698-8581
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COMMENTS
olblackmagic's picture

I was reading this review of the Conrad-Johnson PF-1 preamp, originally written by Martin Colloms on 12/1/90, and came upon a statement he made that evidenced an unfortunate trend that I believe continues currently and is responsible for the bastardization of analog sound in many quarters. When describing the sound of the unit's phono stage he says "There was also a hint of leanness and crispness sufficient to align analog disc sound closer to the accepted sound of CD." Back in 1990 CD sound was indeed becoming the accepted sound for musical playback, however unfortunate it is to acknowledge that. Remember the "Perfect sound forever." mantra? The tonally rich, lush sound that a good analog rig provided was replaced with the harsh brightness and unrelenting sterility and "neutrality" that digital playback brought us. The angelic soul of music, especially acoustic music, was crushed under the demonic boot of this shrill new format. I ardently maintain that the general trend toward making analog playback sound more like digital has never stopped.
I have been reading Stereophile and other audiophile mags since 1986. Back then words like sweet, lush, rich, and one that has virtually disappeared-euphonic, were the benchmarks of premium analog sound. The more a component evidenced these characteristics the better it was. These terms added-up to one thing-MUSICALITY. When digital equipment descended like the plague most of it was rejected by the audiophile mags because it lacked the above-listed traits. The cursed stuff wasn't musical. It still isn't. My fiance has a $4500 SACD player which I recently listened to. It's still very digital. No one with half an ear would ever mistake it for the beauty of analog. A used Systemdek IIx with a Rega RB300 arm and a Shure Ultra 500 cartridge will blow it out of the water and make your soul weep for joy because you've finally heard the thrilling beauty of MUSIC. Digital playback never has, and I doubt ever will, come close to even inexpensive analog.
I'm sorry this is so long. There is another overlying point here which I will address now. In the last ten years or so I've noticed different words being used as benchmarks for most analog equipment. Words like neutrality, clarity, and detail have replaced the former terms that were striven for before. I have almost never read recently in Stereophile or any other audiophile mag that a highly-rated cartridge, turntable, or phono stage was "sweet". Yet this was perhaps the most-used word to describe beautiful treble in years gone by. Especially the reproduction of violins and violas. Why? Because that's the way they sound live. I know. I've been to many classical concrts, both chamber music and symphonio. Digital makes strings sound like the screamings of a tortured cat.
The music hasn't changed. Why have the perceived goals in sound reproduction, as evidenced by the new words used as standards, changed? I contend that the pervasion of digital playback has both influenced the designers of analog equipment and the sensibilities of the reviewers of that equipment. Digital sound has bastardized analog sound. Not in every case, but as a general premise. Sound that is ruthlessly neutral and hyper-detailed is now striven for and is characteristic of much of the analog high-end gear. That's because those traits were thrust upon us by digital playback and have corrupted the tonal beauty and rich lushness that have always been hallmarks of great analog sound-and not only analog sound but the sound of vintage amplication components as well. Many audiophiles are spending a lot of money on vintage gear in order to retrieve this sound. May God bless their tenacity and wisdom. Let's bring this lovely sound to more current equipment so we can really enjoy the "Ol Black Magic". Thanks.

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