Tube Preamp Reviews

We often wrongly assume that a piece of equipment that sounds natural at low volume settings and can play loudly is dynamic. This is far from the truth. To properly re-create dynamics, a piece of equipment must be able to reproduce all of these various volume levels in proper proportion to one another within the same piece of music. If we hear a piece of equipment that gets the softest and loudest passages reasonably correct, we are then convinced it has good dynamic capability. A significant percentage of today's best equipment can get these extreme volume levels reasonably correct, but that, too, is not enough.

The ultimate test of dynamics isn't in the gross differences between the softest and loudest passages, but in the re-creation of very minor differences in volume level—what some refer to as low-level or microdynamics. It is here where much of the emotional wonder of music exists. The Signature simply provided the most lifelike microdynamics I had heard. It let me hear the differing amounts of force a drummer used on different strokes; the differing pressures a pianist used for each percussive note; or the subtle changes in volume used by a vocalist in creating or sustaining a mood.

A wonderful illustration of the use of dynamic contrasts to create moods is Art Zoyd's Nosferatu (Atonal ACD 3008). The Signature was adroit at re-creating this music's emotion. Because it got all of the different volume levels right, the music shifted effortlessly from dark to tension-filled to driving to frenzied. The tonal colors of the bass were visceral. "Song of Sophia" from Dead Can Dance provided a similar illustration of the CAT's dynamic capability, as did the Athena/Rachmaninoff.

In large part, I thought this was possible because the noise floor was lower with the Signature than it had been with earlier CATs and many other competing tube designs. However, Stevens informed me that the signal/noise ratio for the Signature was the same as it had been for the Reference Mk.II. What's new is the apparent elimination of various distortions coupled with the reduction of vibration-induced grundge and hash. With the resultant quieter backgrounds, very delicate/soft passages were glorious (eg, Goran Sollscher's guitar with the conductorless Orpheus Chamber Orchestra, DG 429 232-2). The apparently lower noise floor allowed subtle shifts in level to become more audible and enjoyable.

Of course, as splendid as the Signature was, it still wasn't live music. Memorex advertisements to the contrary, none of us is going to be fooled into believing the music from our systems is live. While the noise floor of the Signature has been lowered significantly, there was still room for improvement. But I wonder if that improvement can be found using tubes. The latest CAT's extremely low noise floor was a tremendous step forward. In moving so far ahead, the preamp has helped me understand just how critically important the noise floor is. I want more (I mean, less).

The second dynamic shortcoming was a minor restriction in ultimate level. The very loudest passages could have sounded still louder with respect to the rest of the volume range. There appeared to be very minor vestiges of compression during the loudest peaks which were obvious at times with CDs such as Art Zoyd and the Saint-Saëns, as well as with LPs such as the Rachmaninoff.

The tonal splendor and captivating dynamic realism of the Signature were, by themselves, enough to set it among the very best preamps available at any price. But there was more. The preamp's soundstaging ability was superb. With certain recordings, the re-creation of the original acoustic space was uncanny, with width and depth that mirrored the original space. While many preamps can create a sonic hologram in three-dimensional space, the Signature presented an aural sculpture. It was the difference between seeing spatial relationships and believing you could reach out and touch them.

There were many component parts to this overall re-creation of aural sculptures. For starters, the soundstage was as large and wide as the recording allowed. There were no restrictions from side to side or from front to back. Both dimensions were also continuous. There was no left/left-center/center/right-center/right sense of discrete positioning. There were an unlimited number of locations both in width and depth. I verified the preamp's overall soundstaging dimensionality using various test tracks from both the Chesky (JD37 and JD68) and Stereophile (Test CD 2) test CDs. However, the preamp's soundstaging capabilities were much more satisfying with well-recorded music such as Mozart's A Little Night Music with Orpheus (DG 429 783-2), or Rimsky-Korsakov's Scheherazade.

Performers were placed upon the stage with precision. They did not wander or move about. There was nothing vague about their locations. The performers themselves were dimensional within the stage, with substance and body. In addition, there was a sense a space around each performer, as well as a sense of space or distance between performers. This general sense of space was further enhanced by the re-creation of a facsimile of the actual recording venue. The sound of the hall or auditorium was put right in my listening room. There was air and openness, reflected and decaying sounds clearly part of the overall sonic structure.