Analog source: Heybrook TT2 turntable, Rega RB300 tonearm, Koetsu Black/Gold phono cartridge.
Digital sources: Audio Alchemy DDS•Pro, DTI•Pro32, and DDE v3, with Audio Magic I2S cables and Cardas GoldenCross interconnects; Camelot Dragon Pro-2, Uther DAC with Camelot I2S cables; and Straight Wire Maestro II interconnects; Pioneer CD transport, DMX receiver, The Parts Connection Assemblage DAC-2.
Preamplifiers: Klyne 6L3.3P, Sonic Frontiers Line-2.
Power amplifiers: McCormack DNA-1, Sonic Frontiers Power-2 (via Cardas Cross or Straight Wire…
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Sidebar 2: Associated Equipment
In his "From the Editor's Desk" in the March issue of Stereophile's e-newsletter, John Atkinson recounts how, years ago, "erstwhile audio scribe Enid Lumley" demonstrated her pizza-box-tripod tweak at a hi-fi show. Lumley, JA writes, "placed the tripod atop a CD player and convinced her audience—including me—that the sound was better."
The subject of JA's newsletter column was audio tweaks in general, and specifically the recent debate over Golden Sound's so-called Intelligent Chip. This small, plastic-encased device is claimed to permanently improve the sound of CDs. Just place the chip…
Letters in response appeared in July 2005 (Vol.26 No.7):
Unique credibility
Editor: Once in a while, I read an article in Stereophile which makes me wish I could extend my subscription for a decade. Such was the effect of Jim Austin's "As We See It" in May (p.5). To say that it highlighted the unique credibility of your publication would be understatement. While there are many who will value imaginary gains to the exclusion of reality, his wisdom is well-received by those seeking a firmer foothold in demonstrable science.
What Jim said needed saying, and while he will…
Latest and largest in Krell's current range of power amplifiers, the 600Wpc, $12,500 Full Power Balanced 600 joins the 300Wpc FPB 300 ($9000) and the 200Wpc (originally 150Wpc) FPB 200 ($5900). All are single-box stereo chassis and are specified as "Full Power Balanced"—I think to distinguish the essence of these designs from ordinary stereo amplifiers operated in balanced-bridged mode, usually with impaired performance. The FPB 600's speaker output is balanced; ie, neither "positive" or negative" terminals are connected to ground or the amplifier chassis. (Note that no speaker switches or…
Krell's regulation feature is still more impressive when you take into account Krell's "Sustained Plateau Biasing," a patented Krell technique that provides an effective equivalent to class-A biasing—without a long-term power dissipation penalty—by anticipating the size of any and every musical event (footnote 1). It uses high-speed current-feedback circuitry to do this, then holds these required levels in a static condition for tens of seconds after the event is over. This minimizes any possible dynamic interaction of bias level with sound quality. The FPB 600's seven stages of bias…
The FPB 600 was factory-fresh, as was the FPB 300 I reviewed for Hi-Fi News & Record Review in December 1996. That model sounded quite unremarkable when auditioned at first plug-in; while the acceleration in quality was impressive as the early tens of minutes went by, it was a week before a close approach to its final performance plateau had been achieved.
Forewarned by that experience, I broke the '600 in on a diet of stereo music for a week. Thereafter, matters were fairly stable. The FPB 600 can, of course, be left in standby for longer periods of inactivity, and switched off…
Imaging, transparency...
Soundstages were very stable, very deep, very wide, and excellently focused. Layering of perspective was most convincing. The big Krell presented the primary image just right, neither too close nor too distant. There was no detectable shift in perspective or depth with changes in loudness or program complexity. Perhaps as a result, the FPB 600 somehow induced the speakers to perform with greater smoothness, showing unexpected gains in driver integration and the sense of musical coherence. Stereo images floated free of their reproducing acoustic sources and were…
Soundstages were very stable, very deep, very wide, and excellently focused. Layering of perspective was most convincing. The big Krell presented the primary image just right, neither too close nor too distant. There was no detectable shift in perspective or depth with changes in loudness or program complexity. Perhaps as a result, the FPB 600 somehow induced the speakers to perform with greater smoothness, showing unexpected gains in driver integration and the sense of musical coherence. Stereo images floated free of their reproducing acoustic sources and were…
Aside from the choice of cables (not easy, in view of the performance potential), two further areas remain of interest: physical support and mains power supply. Like the FPB 300, the '600 benefits from something more than carpet under it. In any case, if the carpet is too deep, air flow will be restricted. I tried spiked marble slabs to good effect, and a pair of Mana platforms back to back—unwieldy and probably suboptimal, but nonetheless revealing. The floorspikes gave an impression of a deeper, clearer bass and a more solid mid. The platforms gave faster, more tuneful bass with a clearer…
And compared with the FPB 300? All too often, larger amplifiers concede quality for quantity—the treble roughens, and the more powerful amplifier may sound less well integrated, even lacking in clarity. Of course, a big amp can also sound more gracious and bighearted, if at the same time slower, less agile, and perceptibly weaker in terms of rhythmic drive.
Not so the FPB 600. It conceded absolutely nothing to its smaller sibling. I noted a more open, more naturally explosive and better-balanced sound, particularly in the upper mids and treble. Looking back at my notes for the '300, I…
Sidebar 1: Specifications
Description: Two-channel, solid-state power amplifier with Sustained Plateau Biasing output stages. Power output: 600Wpc into 8 ohms (27.8dBW), 1200W into 4 ohms (27.8dBW). Power bandwidth (-3dB): 4Hz-20kHz. Output impedance: 0.03 ohms. Input sensitivity: 4.3V RMS (balanced) for rated output. Input impedance: 85k ohms.
Dimensions: 19" W by 10" H by 25.5" D. Shipping weight: 182 lbs.
Serial number of unit reviewed: Not noted.
Price: $12,500. Approximate number of dealers: 75.
Manufacturer: Krell Industries, Inc., 45 Connair Road, Orange, CT 06477. Tel…