When I arranged to review the Bryston 28B-SST monoblock power amplifier, I wanted to be certain that the 1kW amplifier wouldn't be starved for current. Bryston advised me that Plitron, who manufacture the 28B-SST's toroidal transformer, also make Power Isolation Units (PIUs), under the brand name Torus Power. Torus explained that its PIUs combine surge suppression with massive toroidal transformers to provide AC power conditioning and protection from voltage surges.
I've long admired Vacuum Tube Logic's line of amplifiers and preamplifiers. Owners Luke Manley and his wife Bea Lam routinely appear at the Consumer Electronics and Home Entertainment shows with luxurious, microprocessor-controlled tube gear, soothing new music, good-sounding rooms, and a friendly, unhurried manner. Their show setups are dialed in so well that I often find myself taking refuge there, sitting and listening for hours with other Stereophile writers.
Patrick Chu, creator and designer of the $80,000/pair, two-way, Mandarin Supreme loudspeaker, explained that the products’ name is a synthesis of two words: Loimin means "delightful understanding" and Chay means "ateliar or studio." The frequencies from 750Hz upwards are handled by a 1" tweeter loaded with a 19" horn comprised of alternating layers of cherry and oak wood. The bass, which is rated down to 22Hz, is handled by 10" and 12" woofers. This composite was by far the least active speaker material I've come across. Rapping it with my knuckles was like tapping on granite. The woofer enclosure was made of concrete with a cloth covering. I didn't ask about the loudspeaker's weight because I didn't want to know. The nominal impedance is 8 ohms, and the voltage sensitive a very high 92dB. Although I didn't audition any familiar reference recordings, the speaker had a dynamic sonic texture with a midrange emphasis.
...and 3.6kW into 2 ohms! All in a day's work for Krell's $40,000/pair, Krell Evolution 900 monoblock amplifier. On passive display with its top off, you can see that the amplifier has three output modules, each containing a pair of driver stages, 28 bipolar output devices, and a massive heatsink that vents heat in chimney fashion through vents in the top and bottom of the chassis. The power supply features two 3kVA toroidal transformers, 52 electrolytic capacitors, each rated at 1800µF, 900watt, and 105°F. Weight? Again I didn't want to know, but was told it was a mere 175 lbs!
Todd Eichenbaum, design engineer at Krell, walked me through the design of their new amplifier, the $10,500, 300Wpc 302. The power supply employs a 3kVA toroidal transformer, built-in power conditioning, a current-mirror input stage, a push-pull driver stage, and low negative feedback (8dB) around the output stage. It was paired with the $10,000 Evolution 222 stereo preamplifier.
Krell Industries' new Modulare Duo loudspeaker system was the one active exhibit in their suite, playing music from an excellent sampler of audiophile favorites. Todd Eichenbaum, shown standing next to the $35,000/pair, 300 lb system, explained that the separate woofer and satellite units were made of machined billet aluminum, as with Krell's original LAT-1 speaker system, but the Modulare’s drivers and passive crossover circuitry have been designed for higher current handling. The low-frequency cabinet contains three 8" aluminum-cone woofers, while the satellite section marries a 1" ScanSpeak ring-radiator tweeter, and a 6.5" aluminum-cone midrange driver.
The Pathos InPower monoblock amplifier ($13,500/pair) is a hybrid design offering 80W (at 0.4% THD, 5Hz–60kHz, ±3dB. It features some of the most beautiful industrial design I saw at the show. Designer Gianni Borinato describes it as a balanced, double INPOL power amplifier, with a zero-feedback, hand-matched. MOSFET output stage biased to run in class-A. The point-to-point wiring uses silver wire. Two triode tubes in the input stage are wired in opposite phase to form a double triode that is claimed to minimize distortion. The design proved its merit by driving the Focal 1037 Be loudspeakers with speed, dynamics, and excellent imaging. The room was a favorite among the Stereophile writers at the Show.
"That's an impressive soundstage for a two-way monitor," I thought looking at the diminutive Confidence C1 loudspeaker, but hearing a wide, deep soundstage. Dynaudio's 25 lb pound, two-way ($7000/pair plus $450/pair for two) features a 7" woofer and the Danish company's acclaimed Esotar2, 28mm, soft-dome tweeter. The drivers are mounted on a baffle that is said to be decoupled from the cabinet. Dynamic range was superb driven by Simaudio Moon W-7M monoblocks, thought JA, who thought that this system's reproduction of Stereophile's new Attention Screen CD was one of the best he heard at the Show.
Krell’s new Krell IPOD Dock (KID) only costs $1200, but offers balanced outputs, signal conditioning with bass and treble adjustments, all digital control lines, diverse outputs (2 balanced, 2 RCA, and S Video) with optical isolation. The auxillary input allows one to attach a Zune or Creative Digital Zen MP3 player. The Krell KID received much attention from press and public alike.