Sidebar: Dating Decrepit Drivers
Decades ago, the Electronic Industries Alliance established a source code for manufacturers to use on various finished components: potentiometers, transformers, large capacitors, and the like. I learned about it during the years when I was still buying and collecting electric guitars and amplifiers, and more than once, the code kept me from being burned. (Nothing screams unoriginal quite as loudly as a 1956 Fender tweed Harvard amp with volume and tone controls from the years of the Nixon administration.)
The EIA code is also a boon to anyone just…
Enid Lumley accosted me in the corridors of Santa Monica's BayView Plaza Hotel in March: "That doesn't sound like a real piano!" I was taken aback. The sound to which the redoubtable Ms. Lumley was referring emanated from a 7' Steinway we had hired for James Boyk to play at the Stereophile show. Jim was conducting a series of tutorials on how the sound of a real piano is constituted, so Enid's criticism, on the face of things, seemed absurd. As my face obviously showed this conclusion, she hastily explained that, of course it was a real piano, but the fact that it overloaded the 40-seat room…
However, in general, I feel that to deny the importance of an undeniable aspect of live sound—its time integrity across the whole audio band—is treading on dangerous ground: it cannot be denied that the transient impact of real sound is always lacking in reproduced.
In real life, all the frequency components making up a waveform arrive at the ears at the same time. In the bass, listening tests have shown that changing the time relationship of a low-frequency fundamental with respect to its harmonics—by a high-pass filter, for example—is audible. In fact, KEF's Laurie Fincham has…
Stop me if you've heard this one: Back in the early 1990s, just after the fall of the Soviet Union, I debated professor of music engineering and magazine columnist Ken Pohlmann on a talk show on the CBS radio network. The subject was analog sound vs digital sound, but I guess when Pohlmann felt I was getting the upper hand, he felt he needed to play the tube card. Derisively, he said, "I bet you're one of those tube guys, too, aren't you?" Before I could open my mouth, he continued: "You know, the Soviet Union's military gear, including the MIG fighters, ran on tube electronics, and look…
Pushing the front-panel Power button causes the Mute LED to blink red and the Power LED blue. The Mode light glows green for Tetrode mode, red for Triode; push the Mode button to switch between them, either in Standby mode or after power-up. The entire power-up cycle takes less than a minute, during which time, if you look down through the top cover, you can see the LEDs next to each output tube blink as they indicate that the auto-bias system is adjusting each tube's bias voltage. When every LED is emitting a steady green light, indicating that all output tubes have reached their operating…
Sitting in my usual seat at the center of Avery Fisher's 20th row, I concentrated on the sound. When I got home, I played the Milstein LP, which proved far quieter than the coughing and choking accompaniment provided by the hall full of alter kockers earlier that evening. The first thing I realized was that I'd had the system cranked up way too high during previous listening sessions to ever realistically reproduce the sound of a concert as heard from that hall's 20th row. Turned down, the system achieved remarkably believable, lifelike sound from this disc, though Milstein had been…
Sidebar 1: Specifications
Description: Tubed monoblock power amplifier. Tube complement: one 12AT7, one 12AT7, eight 6550C. Inputs: 1 pair unbalanced (RCA), 1 pair balanced (XLR). Outputs: 1 pair binding posts. Rated power output at <2.5% distortion: 425W into 5 ohms, Tetrode mode; 225Wpc into 5 ohms, Triode mode. Frequency range: 20Hz–20kHz. Output impedance: 5 ohms. Input impedance: 42k ohms. Input sensitivity: 2.0V for full output. Power consumption: 30W at idle, 1000W at full power.
Dimensions: 19" (487mm) W by 9" (230mm) H by 13.25" (340mm) D. Weight: 85 lbs (38.5kg) shipping…
Sidebar 2: Associated Equipment
Analog Sources: Continuum Audio Labs Caliburn turntable & Cobra tonearm & Castellon stand; Graham Phantom tonearm; Continuum Audio Labs Criterion turntable & Copperhead tonearm; Lyra Titan, Air Tight PC-1, Koetsu Vermillion, Clearaudio Stradivari cartridges.
Digital Sources: Musical Fidelity kW SACD/CD player, Esoteric SA-60 universal player, BPT-modified Alesis Masterlink hard-disk recorder.
Preamplification: Manley Steelhead, Einstein Turntable's Choice phono preamplifiers; Musical Fidelity kWP, Balanced Audio Technology REX…
Sidebar 3: Measurements
Although it has only one output transformer tap, VTL's MB-450 Series II Signature can be used with its output stage configured in either its Tetrode or Triode modes. I performed a full set of tests in each mode, using both balanced and unbalanced input connections, but discuss only a representative selection here.
The voltage gain into 8 ohms was the same for both balanced and unbalanced inputs, but varied with the mode. Tetrode mode gave 26.4dB gain, Triode 23.7dB. All combinations of mode and input preserved absolute polarity; ie, were non-inverting. The…
Wes Phillips wrote about the VTL MB-450 II in March 2009 (Vol.32 No.3)
VTL Amplifiers head honcho, Luke Manley, promised me a pair of his MB-450 Series II Signature monoblocks ($13,500/pair) to audition when he delivered a TL-6.5 Signature preamplifier for my Follow-Up in the July 2008 issue. Apparently, it took him a while to pry them out of Michael Fremer's hands. I had other things to worry about, but Michael Fremer's review in the January 2008 Stereophile (Vol.31 No.1) had really piqued my interest. I was once a rabid tubeaholic like Mikey, but have drifted away over the years as…
