Tube Power Amp Reviews

A lot of electrons have flowed under the bridge since I brought you word of the mighty Vacuum Tube Logic Wotan MB-1250 (originally reviewed in Vol.19 No.10). While I was staggered by the awesome presentation of this $27,500/pair monoblock amplifier, I still found a few nits to pick. I was impressed by Luke Manley's "Manufacturer's Comment" response at the time. Instead of Excoriating the Reviewer, he took my nits seriously and said he'd address them. (Hey, he could be Mr. Magnanimous—it was a rave review!)

Fast forward to fall 1997. It was turning cold in New York City, and my thoughts turned to the clanky, recalcitrant radiators in our old loft building. A flashbulb went off somewhere deep inside my noggin: I recalled rather fondly the 24 Svetlana 6550s per side of the huge, heartwarming Wotans. "Hellooooo, Luke!" And before you could say, "They weigh how much per side?" we were once again with Wotan.

The early-build Wotans shipped with their two-storey chassis separated; some assembly required, as it were. The new units arrived in two massive crates (around 700 lbs!) with the ready-to-run monoblocks tied down within. So there was a grinning Luke Manley, there were these huge crates, but nowhere was there even one Big Beefy Guy to help. Luke, typically unfazed, suggested a quick walk to the hardware store for a furniture dolly. That did the trick—Kathleen, Luke, and I managed to unbolt the amps and schlepp them into place in our listening room.

I noticed right away that the chassis frames were much more rigid than before, and that the entire construct was more solidly built and nonresonant. In fact, the entire front panel—top and bottom chassis—is now fashioned from one huge sheet of aluminum. "Yeah, they can't go rhomboid like that!" exclaimed Luke. I hate when that happens.

The top deck itself is thicker, and the bolts of the output transformer go right through to the bottom cover plate of the top chassis to further enhance structural integrity. The amps are obviously better finished, and sport a beveled edge at the back of the top and bottom chassis for added stiffness and easier access to control functions and cabling. There's also an easy-to-remove tube cage covering the top floor, which I popped off only to bias the tubes. The Wotans now offer both single-ended and balanced inputs, and, as before, switch-selectable triode or tetrode operation. (Remember, ladies and gents, we're talking about 650Wpc in triode and a whopping 1250 big ones per side in tetrode.) The front-panel two-stage turn-on switch is nicely robust, and proved completely trouble-free in operation.

Instead of the previous complement of three power transformers in the power supply, there are now five serving various functions: B+ for the input stage, separate B+ for push'n'pull sides, and separate push'n'pull transformers for the tube filaments. But you can't see them; the entire "bottom-floor" chassis is potted in rubber—very kinky—which keeps mechanical resonance to an absolute minimum. I also learned that the multiple printed circuit boards of the earlier design had been replaced with a single 24" by 24" pcb to prevent flexure. (That's what broke a ground trace and drove us crazy in the first pair we auditioned.) Star-grounding has also been implemented; all grounds have their own trace back to the star-ground point.

I've listened to the new Wotans with TARA Labs The One, Synergistic Research Designers Reference, XLO Signature, and Ensemble MasterFlux cables and interconnect. Preamplifiers included the BAT VK-5i/VK-P10 combo, the YBA Signature 6 Chassis, and the Nagra PL-P. (The Nagra got along famously with the huge monoblocks—I never heard the PL-P sound so sweet, dynamic, and involving.)

The loudspeaker was our new reference, the JMlab Utopia—a speaker with which I am utterly in love. You might think that 650Wpc into a load as sensitive (94.5dB) as the Utopias present might be overkill. But this was certainly not the case, especially as the Utopias fall to near 3 ohms in the bass.

The sound produced by the Wotan-driven Utopias was awesome. The grip and control in the bottom end always riveted me to the Ribbon Chair. In the Utopia review I'd been a touch equivocal about the French speaker's bass. Now, set a touch farther back and a hair closer together than before, and in the lusty grip of the mighty Wotans, I can say that I'm getting the best bass I've ever heard in our system.

While I'd mentioned in the original Wotan review that some of the solid-state boys got the bass better and tighter, I can now say . . . fawgedaboutit! The extension, speed, transparency, pitch differentiation, control, and ungodly power in the nether regions knocked me out each time I listened at foundation-rattling levels. Really, it was incredible. Mighty macro to nuanced micro, the bass was always totally majestic, sweeping, and encompassing, utterly acoustic and visceral. I've never heard any other amp—tube, hybrid, or solid-state—that dishes the bass like the Wotans managed in our system.

I'd also mentioned that the Wotan was a shade less subtle and refined then the Jadis JA-200, and a hair more grainy. That was then, this is NOW! Subtle and refined? Absolutely! Grainy? NOT! Power to spare? By the boatload! Tonal color and shading? First class! Midrange magic? Nothing but the best! Sweetness and extension in the highs? Never better! Integration of initial transients with follow-on harmonic bloom and decay? Perfect! Caveats? None! Nitpicks? Not a one!

Well...the Wotans do run fairly hot, and biasing 48 output tubes individually is a bit of a pain—but at least you won't need matched sets. And the Wotans held their bias quite well with Svetlana 6550Cs, needing very little attention in that way. Additionally, the nonresonant built-like-a-tank structure meant that most tweaks were largely ineffective. Ensemble Tube Sox or Midas Bluenote Tube Dampers made no appreciable difference. (A Shakti Stone perched atop the tube cage just over the output transformer did make a small but noticeable improvement, however.) In fact, the only tweak that really worked, and one that I recommend to all VTL owners (and to all tube-amp owners, for that matter), was popping them onto PolyCrystal amp stands. This paid immediate dividends by tightening up the entire sonic presentation and keeping the awesome bass range tighter and deeper'n'hell. The PolyCrystals also raised the already wonderful imaging a notch further toward ultimate palpability, all the while enhancing air, transparency, and focus.

I've heard many audiophiles say their systems sound pretty good sometimes, rather bad at other times, and, on rare occasions, out-of-this-world fantastic (usually on weekends or in the evening, when the power grid is behaving). I understand; I've felt the same way for years. But with the mighty Wotans driving the Utopias, listening was always an orgasmic experience. Each time I fired them up, I knew I was going to be hearing the best of the best. As an exercise in creating an ultimate statement product for their company, Luke Manley and Bea Lam are to be congratulated for having succeeded beyond even my wildest dreams.—Jonathan Scull