Tube Power Amp Reviews

Years ago, while editing Listener Magazine, I received a call from a record-company publicist with whom I was friendly: The drummer Ginger Baker, whose work I admire, was promoting a new release, and we were offered a 30-minute telephone interview with the artist. I jumped at the chance, but wound up leaving the article in the can—partly because it was so short, partly because its subject was so cranky. As with vacation trips to certain locales, second prize would likely have been 60 minutes with Ginger Baker.

For anyone who's been around the audiophile block a few times, Conrad-Johnson Design is a brand that needs no introduction. My first acquaintance with Conrad-Johnson was before I began writing for Stereophile (more than two decades ago—time sure flies fast when you're having fun!). I was in the market for a new preamp, having become convinced that my Dayton Wright SPS Mk.II was the weak link in my system, and had narrowed my choices to two similarly priced products: a solid-state model made by PS Audio (I'm not sure of the model number), and the tubed Conrad-Johnson PV-2ar. They were carried by different dealers, who allowed me to take their preamps home over the same weekend for a direct comparison. I was impressed by both preamps, and was sure that either would represent an improvement over the Dayton Wright, but in the end decided to go for the PV-2ar. I later traded it in on a dealer's demo unit of another Conrad-Johnson preamp, the PV-5. And, as it turned out, one of my first reviews for Stereophile was of Conrad-Johnson's PV-11 preamp.

The Audio Research D-160B has been heavily modified since the D-160A, and uses the same technology as the D-70, D-115, and D-250. It embodies William Z. Johnson's latest transformer and power supply designs, his latest choice of capacitors and resistors, and the same independent regulation of screens, drivers, and front end. D-160s and D-160As can be converted to D-160Bs for $1500.

Most reviewers look for a "hook" or angle of some kind when it comes time to write a review. After all, how many ways are there to get excited about audio equipment? Kathleen and I like to focus on the human side of the High End. So it was with some amusement that I watched the obstacles swirl around what I thought would be a fairly straightforward review of the Vacuum Tube Logic MB-1250 Wotan monoblock power amplifier. My thought was to return from single-ended to push-pull with a bang! I'll say...

It all began at the January 1996 WCES, where I found my shorts positively welded to the listening chair during a memorable musical blast at VTL. Luke Manley and his extreme audiophile wife Bea had a good thing going and they knew it. People were talking. "Did you hear those monster two-storey VTLs on the Alón Vs?"

The VTL MB-450 series began life in the late 1980s as the Deluxe 300, a pair of which I once owned. Over the years the basic design has been improved and modified, in the forms of the MB-450 (1996) and the MB-450 Series II (which I reviewed in January 2008). The tube complement remains the same: eight 6550s in the push-pull output stage, a 12AT7 input tube, and a 12BH7 driver. Into a 5 ohm load, the MB-450 III is claimed to produce 425W in tetrode mode or 225W in triode, from 20Hz to 20kHz.

Victor Tiscareno and Byron Collett of AudioPrism are known in audiophile circles for their complete line of power-conditioning products. (See Barry Willis' omnibus review in the December 1998 Stereophile.) Their intimate knowledge of the ever-capricious electrical supply has resulted in a series of front-end components bearing the company's logo. The flagship Mana Reference monoblocks, under consideration here, represent AudioPrism's collected wisdom and engineering savvy taken to its logical extreme.