Krell KRC preamplifier

Compared to the Krell KSA-300S power amplifier that I also review this month, the KRC preamp's design is, at first glance, almost conventional. But its thoroughly high-end internal design has been equally well thought-out and executed. Its main, four-layer, glass-epoxy circuit board is for the audio signal, DC power, and ground—two layers for the latter are said to minimize noise. The gain stages are pure class-A and complementary. As in the amplifier, the circuit is direct-coupled, with servo circuits controlling the DC offset. The fully regulated power supply is housed in an external chassis. Seven inputs are provided: four single-ended, two balanced, and one single-ended tape. All inputs are line-level except for the optional, single-ended phono stage. (This review will address the line stages; a Follow-Up will discuss the phono stage's operation.) There are three outputs: balanced and single-ended main outputs, and a single-ended tape output.

The KRC is set apart from previous Krell preamps by its remote-control capability. Level, balance, mute, input selection, tape-monitor selection, absolute phase, and gain (the LED-illuminated high position provides an additional 6dB of amplification) are all accessible either from the front panel or from the hefty remote control. The latter also duplicates the bias-level meter on/off controls found on the Krell S-Series power amplifier remotes (footnote 1). The balance "control" provides up to 4dB of attenuation in 1dB steps, or off, for either channel. The volume is controlled via a custom-designed, motor-driven, continuously variable potentiometer. When the volume is operated via the remote, a red LED on the control knob illuminates, so the setting can be seen from across the room.

The KRC also provides an unusual degree of input and output protection. Faults are sensed, disabling the offending input or output until the problem is cleared. Problems are indicated by means of flashing input LEDs (for input faults) or a flashing blue pilot-light LED (for output faults).

Interestingly, the KRC (and its outboard power supply) is now the "hot" performer, running not alarmingly hot, but definitely more than warm—even in idle.

After getting a good handle on the performance of the KSA-300S in my reference system, I now moved the KRC into the preamp position. I used the low gain setting for all my listening—it proved more than adequate to the task at hand, in balanced or unbalanced mode. The balanced outputs were used, however, unless otherwise noted.

Striking. That's the only way I can describe the combined performance of the KRC and KSA-300S. Listening to Mokave, Volume 2 (AudioQuest AQ-CD1007), I noted immediately that it had never sounded better in my system, with an outstanding combination of instrumental weight and body combined with clarity and openness. The timbral weight of instruments was fully developed, without lapsing into heaviness. The bowed double bass, in particular, had a realistically gutsy quality, combined with an airy, rosinous sheen. The top end was pristinely clean and detailed yet grainless, sounding in no way etched or electronic. Christmas Time with the Judds was delicate, open, airy, and in some ways a new experience: to rip off Gertrude Stein (by way of Sam Tellig), there was more "there" there. I was troubled by neither brightness nor excessive warmth. Particularly impressive was the way I could follow the backup vocal line better than ever. Focus was particularly fine throughout.

The reproduction was perhaps a bit more analytical than with the Rowland preamp in the system. There was an improvement in overall precision, but with a sacrifice in "bloom." Certainly the sound here would not be mistaken for classic tube sound. But I don't think that's bad. There was no superfluous warmth or richness, but neither was the sound hard, edgy, electronic, or cold in any way. It was fast, airy, and transparent, images properly sized within a soundstage that was tight, wide, and deep.

I referred above to the KRC's reproduction as "gutsy," a word which cropped up more than once in my listening notes. "Gutsy," the antithesis of "muddy," implies a natural resonance which belies the muddle plaguing far too many components' midbass–through–lower-midrange region. The Flying Bulger Klezmer Band (Dorian Discovery DIS-80106) is a superb recording and a lot of fun (footnote 2). Here, again, the Krell combination reproduced the gutsy, even lusty quality of croaking double bass and blatting alto horn. All this with a natural edge—a difficult feat. Surprisingly, on this and other recordings, there was less of what I'd always considered to be excess room (and loudspeaker) warmth than I have ever noted before. While no conventional electronics can cure room modes (DSP is another story—complex, controversial, and still very much in its infancy), clearly something right was happening. While the recording itself gets a bit congested on peaks, the sound here was otherwise beautifully transparent, the solo instruments and voice lively (in the positive sense) and involving.

When I brought the Rowland Consummate back into the mix for a direct comparison, my initial impressions were confirmed. The Rowland sounded more soft and sweet. The KRC's viselike grip was replaced by a more relaxed, rounded presentation. It had its own charms, to be sure—sweet without ever being quite tubey, laid-back without sounding recessed. This seems to be typical of Rowland—it certainly was characteristic of their Model 1 amplifier which captivated me a few years back. But the Krell KRC had a tighter, more detailed, dynamic, and—that word again—gutsy sound. This was not an easy conclusion to reach—I own the Consummate—but the KRC lifted another veil from the sound.

Footnote 1: The owner's manual cautions against turning the amplifier on or off with music playing—easy to do inadvertently with the remote switches. However, Krell advises that they have always had such a caution, and that the likelihood of damage from this action is, ah, remote.

Footnote 2: Klezmer is traditional Yiddish dance/folk/party music that will probably be recognized by most readers, even if they can't recall exactly where or when they heard it. Here it's re-created by six instrumentalists plus a solo vocalist. How can you resist numbers like "Araber Tans," "Fishelekh in Vasser," and "Der Yiddisher Soldat in Die Trenches"? Well, maybe you can.

Krell Industries
45 Connair Road
Orange, CT 06477-3650
(203) 298-4010