Krell KRC preamplifier Phono Module
In the January 1994 Stereophile I reviewed the $6300 Krell KRC remote-control preamplifier as a line-stageonly device. While most preamps these days do not come standard with a phono stage (sad but true, according to manufacturers I've surveyed), most do make some provision for customers who still value analog reproduction.
Such is the case with the KRC. For an extra $500 (a reasonable price for this option among today's high-end preamps), the KRC owner may obtain the KRC Phono Module at any time. Installation doesn't appear to be difficult, though I recommend you have the dealer do it. Once the module is on board, the KRC becomes a full-function preamp, ready to handle all audio sources, with the phono stage appropriating input 1 (unbalanced).
The module consists of one very large circuit board which fills nearly one-third of the width and the entire depth of the KRC chassis. DIP switches allow gain adjustment. Another row of DIP switches allows the user to select load values ranging from 10 ohms to 47k ohms.
I inserted the KRC with Phono Module into the same system I discuss elsewhere in this issueApogee Mini-Grand loudspeakers bi-amped with two Krell KSA-300S power amps. The source was a VPI HW-19 Mk.IV turntable (not a recent sample) with an SME V tonearm (also an older sample) and a Lyra Clavis cartridge. I limited my listening to the MC modethe mode most likely to be used with such a product.
I found the Krell Phono Module's sound to be excellent from the start. The overall balance was less weighty than that from CD through the KRC, but this is a not-unfamiliar quality of the Clavis cartridge. Openness, detail, and transparency were all convincing. Depth, when present on the program material, was all I could ask for.
This wasn't a tube sound, but it wasn't a lean, antiseptic sound either. Sweet recordings were reproduced sweetly; inherently crisply detailed recordings were rendered that way. If the recording lacked some of the lush three-dimensionality that tube lovers cherish, the KRC Phono Module made up for it in its clean, clear reproduction. Or if it had a fault, it would have to be a slight tendency toward brightness, a bit of "analytic" character. But that was only evident on a small percentage of program material. Through old favorite after favorite I was impressed by the performance of what is, in high-end terms, a moderately priced phono stage. On the superbly recorded choral recording Flöjten spelardansen gar... (Proprius PROP 7759), the overall balance was sweet, yet it in no way sounded veiled. The top end was subtle here, with plenty of detail within the chorus and an effective sense of depth.
Tuxedo Cowboy's Woman of the Heart (AudioQuest AQ-LP1002) was similarly compelling. The guitar in this recording was warm, rich, yet had pristinely detailed transients where called for. The cello, despite the slightly lightweight balance, was full-bodied, and the vocals were convincingly suspended in space. Particularly notable was the rendition of layered depth on "Makoshika Dance."
One of my most effective phono test discs is, appropriately, the Ortofon Pick Up Test Record (Ortofon 0003)a strikingly well-recorded compilation of everything from organ to jazz band to vocals to guitar, with tracks taken largely from the Opus 3 and Proprius catalogs. Through the KRC Phono Module, the result was superb: a layered sense of depth and a wide soundstage on chorus and organ, three-dimensional solo vocals, naturally rich classical solo guitar soundnothing here sounded wrong.
Despite a balance favoring quickness and a spacious airiness over weight and drama, the sound didn't lack for extension. One of my favorite bass torture-test LPs is The Rhythm Devils Play River Music (Wilson Audio W-8521), which has all sorts of grumbly, growling, low bass. (The music is very atypical of the usual Wilson Audio faresort of a downbeat Däfosand the bass extension is exceptional, even for self-proclaimed bass-freak Dave Wilson.) The KRC Phono Module had no problem handling it.
Against the Vendetta
With this review I had no truly familiar phono front enda disadvantage. For a number of reasons, including malfunctions of a turntable and an arm, and the return of another armmy long-term reference Grahamfor updating, the VPI/SME/Clavis system was gathered together for this review. I was familiar with each of these itemsarm, turntable, and cartridgeindividually, but not in concert. There were only two things which marginally bothered me about the performance: the lightish balance and a tendency toward brightness with a small percentage of difficult program material. The latter may well have been exacerbated by the Clavis's overall balance combined with the Mini-Grands' tendency to be unforgiving in this region. However, the only way to be certain that these qualities weren't in the KRC Phono Module was to try a different phono stage. I planned such a comparison in any event, and to that end rounded up the Vendetta dedicated phono preamp with its line-level output.
With the latter plugged into one of the KRC's line inputs, the games began. There were two objectives here: first, determine if the two characteristics I've noted were in the KRC Phono Module; second, compare the overall sound of our long-term reference Vendetta SCP-2 (the source of an ongoing custody battle between RH, JA, and me) with that of the Krell's own phono stage.
The first thing I noticed was that while the Krell KRC Phono Module was very quiet at any normal listening level (no hum, and only a very slight rushing sound audible very close to the loudspeakers), the Vendetta was awesomely silent sans music playing, with noise totally inaudible at any distance from the loudspeakers. It was more like a line stage than a phono stage in this respect. The Krell was completely satisfactory, but the Vendetta was simply spooky in its lack of noise.
Sonically, the Vendetta didn't substantially change the overall system balancethe sound was still a bit light rather than rich, but not unacceptably so. This was clearly not an inherent characteristic of the KRC Phono Module. With respect to the top end, the differences weren't profound, but did favor the Vendetta. The latter was a trace sweeter, though no less detailed, and was also marginally less up-front. The net result was a bit more delicacy and a more self-effacing character, with a more subtle rendition of ambience and inner detail. Some of the brightness noted remainedthough no more than I've noted from the Mini-Grands elsewhere.
What was probably happening was a pileup of trendsthe light balance of the phono, a slight brightness in the KRC Phono Module, and a bit of the same in the Mini-Grandsin my listening room. While the net impact didn't affect most program material, it does argue for careful matching of the turntable/arm/cartridge, KRC Phono Module, and loudspeakers for best resultsalways a good procedure.
If carefully matched with its associated components, the KRC Phono Module is capable of very fine performance. It shouldn't be surprising if the KRC Phono Module wasn't quite up to the Vendetta's level in a head-to-head matchupbefore the Vendetta was (unfortunately) discontinued, it was five times more expensive than the Phono Module. This is not to say, however, that the Phono Module is unsuitable for cost-no-object analog front endsfar from it. It'll certainly hold its own in such company. But while the KRC in its line-stage configuration belongs in Class A of Stereophile's "Recommended Components," I would put the KRC Phono Module in Class B.
This is nothing to be ashamed of, and no mean feat at its price. Krell is to be commended for keeping the Phono Module in its line, giving KRC owners a real incentive to retain superior LP playback capability in their systems.Thomas J. Norton
Footnote 1: Specifications: Frequency response and RIAA error: 20Hz20kHz ±0.1dB. Input impedance: 10 ohms to 47k ohms, user-adjustable. Gain: 64.5dB (MC), 36.5dB (MM). MC overload: 4.8mV at 20kHz. S/N ratio (A-weighted): 80dB MC; 95dB MM. THD: <0.03% (MC); <0.01% (MM).