Listening #53 Page 2

More or less the same mu-follower circuit—doubled up and configured as a differential amplifier—is used to drive a Circlotron output section in all Joule Electra OTL amps. Notwithstanding his admiration for Karsten's single-stage OTL, Barber opted for extra gain so that he could apply a little negative feedback—or at least give the user an option to dial it in. Even without feedback, the 80Wpc VZN-80 amplifier I've been using has a usably low output impedance of 10 ohms. This is accomplished by using multiple output tubes in parallel—in this case, the already-low-impedance 6C33C—in which scheme their impedance falls like that of a resistor, and is subject to the very same mathematical formula. [Each doubling of the number of parallel tubes/resistors halves the total impedance.—Ed.]

And that's where the heat comes in: Like most OTLs, the VZN uses lots of output tubes, and that 6C33C has a very large radiating surface, as these things go. Voilà: It's a music amplifier and a space heater!

Big and Beautiful
Like all Joule Electra amplifiers, the VZN-80 is big and beautiful, crafted into a neat wooden chassis that cradles the parts just so, in order to shrug off troublesome vibrations without similarly troublesome mass. Near the top is a large circuit board that's mostly devoid of circuit traces—hookup wire and the component leads themselves are used to make most of the connections—while various chokes and power-supply caps reside at the bottom of the box. Electrical energy is rectified, divided, isolated, smoothed, and stored in the main chassis, but it's supplied by a beautifully finished external box containing an old-style Variac, included in the price of every Joule Electra OTL amp.

To the hobbyist who isn't used to interacting with an amplifier—my Quad II monoblocks don't even have on/off switches—the VZN-80 will come as a surprise. The Variac's main control is a gloriously huge old knob that will have you crying, Hurry, Fritz, the storm is nearly at its peak!! every time you power up your hi-fi system. Apart from that, my Joule Electra loaner included 14 potentiometers (12 for adjusting bias on individual tubes, 2 for dialing in various amounts of negative feedback), 14 pushbuttons (for selecting which of those pots is to be activated at any given time), two toggle switches (for muting the left- and right-channel input jacks, when needed), and a digital voltage display.

But I hesitate to mention the above, for one very good reason: Once I had it up and running, and after I'd checked a few times to ensure that the various values weren't drifting (initial settings are made at the factory), the VZN-80 was remarkably stable—not to mention noiseless, humless, and unfailingly reliable. It demanded only that I pay attention to whatever record was playing at a given moment.

What did a modern, well-made OTL amplifier sound like driving my 50-year-old Quad ESLs? The combination was downright dreamy. My friend ">Harvey Rosenberg, who died in the summer of 2001, spoke passionately about a great many things in domestic audio, but few ideas fired his imagination as much as the pairing of Quad electrostatic loudspeakers with OTL tube amps—and I finally know why. Took me long enough.

The sound of the Joule Electra VZN-80 was much like my memory of the fine Atma-Sphere M-60 OTL amplifier, which I wrote about for Listener 10 years ago. The Joule was remarkably neutral: as colorless an amplifier as I've ever heard, regardless of parts or circuit design. Malcolm Arnold's recording of his own Symphony 5 (LP, EMI ASD 2878) is filled with lots of delicious-sounding instruments—celeste, glockenspiel, saxophone, and some vivid writing for trumpet and clarinet—and the VZN-80 did a much-better-than-average job of letting those sounds sound like themselves. In a similar sense, it was a faithful, believable re-creator of vocal sounds from classical and popular recordings alike. Choral music, such as John Adams' moving On the Transmigration of Souls (CD, Nonesuch 79816-2), benefited from the Joule Electra's good sense of scale, and clearly delineated soundfield depth as well.

The VZN-80 was also a remarkably textured amp. Acoustic guitars and mandolins sounded as if they were made of deeply grained wood and strung with steel-and-bronze strings. At the other end of the spectrum, the plucked violins toward the end of the first movement of Brahms' Symphony 2, with Pierre Monteux conducting the London Symphony (LP, Philips/Speakers Corner 0835 167), popped out of the soundfield in a manner that escapes even my sweet little Quad IIs.

At times I thought the Joule Electra had a little too much texture, as in Leonard Bernstein's emotionally rich recording of Barber's Adagio for Strings (in this instance, from a preciously but not inappropriately titled Bernstein CD collection, A Total Embrace: The Conductor, Sony/Legacy S3K 90578). The highest notes of the violins were a little overcooked—too much rosin, too much vibrato—but I suppose that may have been the truth, and in any event I'd prefer that to the comparative sterility and exaggerated smoothness of other amplifiers.

The VZN-80's only other notable shortcoming was its lack of tightness and timing accuracy in the bass—especially on uptempo pop records, which sounded more sluggish and less exciting than through my Naim 110 or even my Fi 2A3 Stereo amplifier. But the former lacks the Joule Electra's believably fleshed-out midrange—Jud Barber calls it timbral bouquet, which is a better way of describing it than anything else I've heard lately—and the latter doesn't have the same combination of musical immediacy and reasonably high power. Using the VZN-80's top-mounted pots to dial in some negative feedback helped tighten the bass, of course, but I found that even small amounts of feedback detracted from the amplifier's other charms. I enjoyed doing most of my listening without it.

In all, my Joule Electra experience was a heavenly one—as one would expect from a thoroughly handmade amplifier of this caliber. The basic VZN-80 retails for $12,000, with a number of extra-cost options available, including a chassis made of solid, instrument-grade tonewood (as opposed to the marine plywood used as standard), which is actually tuned like the soundboard of a guitar and finished in the color of one's choice. Other Joule Electra models offer increasing levels of output power, all the way up to the 350Wpc VZN-350 monoblocks, which sell for a not-unreasonable $30,000/pair. Warm wishes, indeed.

Long-term Receptacle Failure
In my column in the November 2003 Stereophile, I described the advantages, theoretical and real, of replacing an audio room's AC receptacles with the premium-quality replacements offered by PS Audio. It seemed to me at the time that the Power Port ($49.95), a hospital-grade dual receptacle made to PSA specs by the Hubbell Corporation, offered easier installation, better sound, and a tighter grip on my equipment's AC plugs than any of the other sockets I'd tried.

Those first two qualities remain unfazed, but the third has gone to hell in a handbasket. While I hesitated to mention this the first time it happened, I must now report that the ground-lug contacts on two of the three Power Ports I installed in my hi-fi room have failed: The opposing contact surfaces appear to have become bent or dislodged just enough that they now converge toward one another near the opening, resisting entry by all but the most compact, pointy-ended plugs. Maturity and good taste have prevented me from reaching for any of a number of cheap, obvious sexual metaphors.

Granted, as someone who swaps components in and out of my system with crazy regularity, I put a higher-than-usual strain on my Power Ports. Still, for a product that costs several times the price of even the good Hubbell products available from other sources, this receptacle ain't acceptable. I encourage PS Audio to find a cure.