Joule Electra VZN-80 MK V Emerald OTL Stereo Amplifier

Is it a cult or the real deal? A look at one outputtransformerless tube amp

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.