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When I reviewed VTL's MB-750 monoblock amplifier in the December 1997 Stereophile (Vol.20 No.12), it was a transitional time for the company. Luke Manley had recently taken it over, and he and his wife and partner, Bea Lam, were aggressively retooling. They introduced new business systems, including rigorous inventory and quality control; rebuilt VTL's dealer network around top-rank dealers; and systematically upgraded the products themselves to improve their consistency, reliability, manufacturability, and performance. VTL's goal, Luke explained to me at the time, was to build amplifiers…
"But the biggest thing is the precision regulated power supply. Along with maintaining correct bias, the way to keep tubes at their optimum operating point is by regulating the high tension power supply. Normally, the voltage begins to sag as power is pulled out of the supply, and B+ voltage might drop by as much as 10%. The S-400's supply never varies by more than 0.1% or 0.2%.
"The S-400's supply is essentially a power amp in itself. The regulation requires six 3300µF capacitors and five 800V, 30A MOSFETs. They've got tremendous transconductance, so when the caps dump, the regulation…
Sidebar 1: Specifications
Description: Tubed stereo power amplifier. Inputs: 1 pair unbalanced (RCA), 1 pair balanced (XLR). Outputs: 2 pairs binding posts. Tube complement: two 12AT7, two 6350, twelve 6550C (KT88). Rated power output at <3% distortion: 300W into 8 ohms (24.8dBW), 400Wpc into 4 ohms, tetrode (23dBW); 150Wpc into 8 ohms (21.8dBW), 200W into 4 ohms (20dBW), triode. Frequency response: 10Hz–125kHz, +0/–3dB. Output impedance: ca 1–1.5 ohms. Input impedance: 57k ohms. Input sensitivity: 2.2V for full output. Power consumption: 480W at idle, 2500W at full power.
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Sidebar 2: Associated Equipment
Digital Sources: Burmester 001, Cary CD300/303 CD players.
Analog Source: VPI TNT HR-X turntable & tonearm, Lyra Titan cartridge; Sutherland PhD, Ensemble Fonobrio phono stages.
Preamplification: VTL TL-7.5, Sutherland Director, Placette active line stages; Placette Remote Volume Control, Sonic Euphoria PLC passive line stages.
Power Amplifiers: VTL Ichiban, Simaudio Moon Rock, Mark Levinson No.20.6 (all monoblocks).
Loudspeakers: Thiel CS6.
Cables: Interconnects and speaker: Nirvana S-X Ltd., Audience Au24, Nordost Valhalla, Silversmith…
Sidebar 3: Measurements
For logistical reasons, I measured a different sample of the S-400 to the one BD auditioned. My sample had been used at the Home Entertainment Show last May and came to me following the Show, before its return to New York dealer Sound By Singer.
With its choices of unbalanced and balanced inputs, and triode or tetrode output-stage operation, VTL's S-400 is four amplifiers in one. To make measuring its performance feasible, I carried out complete sets of tests for both triode and tetrode operation in balanced mode, spot-checking some measurements via the…
Man, has Balanced Audio Technology come a long way in a short time. I think partners Steve Bednarski and Victor Khomenko have comprehensively put the kibosh on the notion that newcomers can't succeed in high-end audio.
"After one year of setup," Bednarski told me, "we debuted our line at the January '95 CES. You know, Victor and I came out of Hewlett-Packard, a real pay-as-you-go company. And that's how it is here at BAT—no outside financing, no debt, and, I'm happy to say, a loyal and growing customer base." BAT is one of the few high-end companies that can claim a genuine…
Remember, the review process is a starting point from which to build your own tastes with continued experience. Don't panic—the search for best sound can bring great satisfaction and enrichment to your life. Why else would everyone gets so crazy behind it, as K-10 would say? In line with this, another, more reasonably priced footering system that worked extremely well was Bruce Bodiak's PolyCrystal cones and spikes. The slightly more upscale G-Flex Schwingungsdämpfer Kugeln were also effective.
Sound
All of the BAT VK-D5's best qualities were those I most often associate with tubes…
Tiger Okoshi's Echoes of a Note: A Tribute to Louis "Pops" Armstrong is one of those great Taguchi-produced JVC XRCDs (JVCXRC-0030-2), and "Basin Street Blues" showed off perfectly the best the VK-D5 can do. And what great music! I was connected, with a strong sense of Okoshi's delight at playing these classic tunes. My notes: "Completely effortless, incredibly airy, with space and bloom. Low-level dynamics are superb. Tiger's horn is razor-sharp, with not a hint of hardness or grain. Transparency is of a very high order; the Radians truly disappeared. Timing is everything on 'St James…
Sidebar 1: Specifications
Description: CD player with tubed output section using six 6922 tubes. Analog outputs: XLR and RCA. Digital output: BNC, 75 ohms. Output voltage: 2V (each phase). S/N ratio: 100dB. HDCD$r compatible. Power consumption: 150VA maximum.
Dimensions: 19" W by 5.75" H by 15.5" D. Weight: 30 lbs net.
Serial number of unit reviewed: 0D070075.
Price: $4500. Approximate number of dealers: 50. Warranty: 5 years if registration form sent in within 30 days of purchase, 1 year otherwise.
Manufacturer: Balanced Audio Technology, 26 Beethoven Drive, Wilmington, DE…
Sidebar 2: I Sing the Body Electric (or Let's Get Differential)
Designer Victor Khomenko goes through a lot when designing BAT products. For one thing, he "listens" to the circuit boards and components.
Victor: "We have to listen to the noise they make to know how they're behaving. Listening through a normal home audio system, you'd hear no noise and think everything's fine. But we have to go deeper than that. Like a doctor with a stethoscope, we amplify the completed boards to check their heartbeat and breathing. The nature of the noise tells us a lot. It should sound uniform,…