Joule Electra VZN-80 MK V Emerald OTL Stereo Amplifier

Equipment report
Tubed power amplifiers
Joule Electra VZN-80 MK V
Joule Electra VZN-80 MK V Emerald OTL Stereo Amplifier

Lacking the literary prowess of HP, I’m at a bit of a loss to explain the cult-like following the output-transformerless (OTL) amp has garnered over the years. I suppose it could be compared to a Harley rider and his bike. If you have to ask what’s so great about a Harley, you probably shouldn’t own one. In the case of an OTL, if you have to ask what’s so special about the simplicity of an output tube directly coupled to your speaker, then you just might not appreciate the utter beauty of it all. Short of actually crawling inside a tube and becoming the music, you’d be hard pressed to feel a closer connection to your system than with a properly designed OTL amp.

Unfortunately, you have to pay the piper for such sonic erotica, which probably explains why you don’t need many fingers to count the number of OTL manufacturers in existence. That output transformer, which ultimately acts as a filter and can’t help but leave its sonic footprints up and down the signal path, also serves an important function in the audio chain. Without it, you’re basically driving a car with no transmission. Obviously, this is no problem on a flat open road. But no matter how much horsepower you put under the hood, those steep hills and inclines are going to give you headaches.

So the rub here is that if you want to do away with the output transformer and its inherent negative side effects you have to carefully match the OTL amp with relatively sensitive speakers. Otherwise, you’ll be getting bogged down on the steep musical passages, and the performance of your system will suffer. Is the extra effort worth it? I’d say emphatically yes, and point to the Joule Electra VZN-80 MK V Emerald as one example why.

Retailing at $16k with the optional Musicwood case and automotive paint finish, the 80W stereo VZN-80 is the “entry-level” offering in Joule’s OTL model line. I have to admit I got off to a bumpy start with this amp when I had to chase the UPS truck down the street because I thought the driver had left a microwave oven on my doorstep by mistake. Turns out it was no mistake. The VZN-80 apparently ships from the factory in a U-Haul microwave box. Knowing how small most high-end audio manufacturers are, I rarely complain about less than professional packaging. But in this case, I feel compelled to speak out. If we are truly serious about extolling the virtues of our hobby to the unwashed masses, how about starting with a dedicated shipping container that reflects the quality of what’s inside? Besides that, I’m getting too dang old to be chasing delivery trucks up and down the block.

U-Haul microwave boxes aside, the VZN- 80 itself looked sharp, with a black acrylic top and Wineberry automotive finish. I was surprised by the substantial size of this unit, as it barely fit on the 19" x 24" Symposium Svelte shelf I used to keep it off the carpeting. While the complement of ten driver tubes came already installed, an octet of 6C33-CB output tubes and a Variac were packed in a smaller, separate box. The Variac is housed in a matching leatherette-covered wooden box with a large rotary knob mounted on top and dual captive power cords for attaching to each channel of the amp. I initially thought both the amp and Variac had missing bottom plates but was told they are left open for ventilation purposes. Basically what you see when you look underneath are the bare (as in unfinished) wood frames of the enclosures. A suggestion might be to paint the underside so it looks a bit more finished.

Before getting to my listening impressions, I’d like to note that according to Joule designer and proprietor Jud Barber, the review sample VZN-80 is a MK V version, with upgraded, professionally made circuit boards. Prior versions all have handmade circuit boards. Other than looking inside, the only way to differentiate a MK V iteration is to check for the letters “MV” along with the date of manufacture on the back panel of the amp.

While I wouldn’t exactly call the VZN-80 a plug ’n’ play component, none of the user settings were difficult to make, save for the bit of angst I developed over the feedback control. Adjusting the bias for both the input and output tubes was as easy as pushing a button, and ramping up the voltage on the Variac to the appropriate level was straightforward, as well. There was a minor issue with buzzing that I was never able to resolve, but it wasn’t loud enough to interfere with my listening.

The sonics of the Joule VZN-80 did give me a bit of a struggle, however. I don’t mean to suggest that the amp sounds bad and I’m trying to figure out a way to dance around it. In fact, looking back at my notes, I saw that my very first comment was to wonder how anyone could possibly be objective about a component that sounded so incredibly gorgeous. I was listening to one of my favorite vocal harmony tracks on Nickel Creek’s Nickel Creek [Sugar Hill] and, as cliché as it sounds, I’m sure my jaw was scraping the floor. I doubt my initial listening impressions could have been more favorable.

After further auditioning with a variety of music and a side-by-side with another OTL, the struggle ensued, as everything I heard through the Joule was sounding perhaps too gorgeous—to the point of being overdone. The lushness was ofttimes too lush, masking detail, and the rich tonal colors were almost too rich to sound real at times. Adding feedback (via the feedback control) thinned out images and brought back missing air and detail but at the same time washed out the vibrant tonal color. So at the suggestion of Jud Barber, I thought it best to leave the feedback control at the factory setting (9 o’clock), which I am told is 4dB of feedback.

The comparison I performed was against the Atma-Sphere M60 monoblocks. While the two amps are quite different—and neither one perfect—it was still a weekend of OTL bliss for me. For speakers I used the very capable and tube-friendly Coincident Super Eclipse (along with the highly detailed and open Coincident TRS Extreme speaker cable), while the Atma-Sphere MP-3 preamp and Meridian G08 CD player held down front-end duties.

The M60 was decidedly more neutral, open, and airy without a drop of lushness in sight. Listening to Dave Grusin’s “Baby Elephant Walk” on Two for the Road [GRP], you could drive a truck through its wrap-around soundstage and superb separation of instruments. While I’d still give the Joule relatively high marks for three-dimensionality, I’m afraid I can’t say the same for its separation, especially not on this particular piece of music. The muted horn had superior tonal color with the Joule, but much better detail and leading-edge definition with the M60. And while both amps were surprisingly gutsy when driven hard, the Atma-Sphere (with 25% less rated power) showed signs of strain at high playback levels. A fairer comparison, both price- and power-wise, would have been with the Atma-Sphere MA-1, which, unfortunately, I no longer have on hand.

The Joule never cracked under pressure, at least not in my smaller listening room, and had substantially more dynamic slam than I anticipated. Bass notes had considerable weight and roundness, but lacked specificity and detail. On Misty River’s “Black Pony,” from Live at the Backgate Stage [Misty River], images were clumped too closely together in the center of the soundstage, making it a bit difficult to sense the space between the performers and instruments. The bass fiddle could be heard somewhere in the mix, but image placement wasn’t specific enough, nor was there sufficient detail, to give the impression of the strings being attached to the body of the instrument. The vocals were velvety smooth and lovely, however, with remarkable density and body. The music was also quite spirited and lively.

Although the Symposium Svelte Shelf worked sufficiently well to keep the VZN-80 off the carpeting, I was disappointed that I never had the opportunity to try the Critical Mass platform that is specifically made for this amp. (It even has the same matching Wineberry automotive paint finish.) I have it on very good authority that this platform makes a fairly dramatic top-to-bottom improvement in the performance of the Joule amps and may have substantially changed the outcome of this review.

I actually had the Critical Mass platform in my possession for a brief period of time before starting this review, but had to send it back. Just for grins, I thought it might be interesting to give it a trial run under my McCormack DNA-500 amp. Instead of the factory Delrin interface blocks, I opted to use some aluminum blocks I had on hand, with surprisingly good results. When I related this to the manufacturer, he immediately asked for the return of the platform, saying it must have sustained shipping damage. (Huh?) I never saw it again. Apologies were fruitless, and I’ve yet to figure out what I did wrong. I relate this story as an example of the weirdness in this hobby and also to encourage readers to try the VZN-80 with the Critical Mass platform. If my source is correct, it will be well worth the effort.

Even with the VZN-80’s few shortcomings, there’s no arguing that this is one colorful, lively, and gorgeous-sounding amp with the rare allure only an OTL design can bring to your system. I’m also willing to concede that my perception of the Joule as being “overdone” could simply be a matter of taste—or lack thereof. If you’re a fan of lushness and bloom from the Old School of tube design, the VZN- 80 will eat you alive. And all I can say to that is, what a way to go! TAS