Bias current and plate voltage for Air Tight ATM2?


I've owned an Air Tight ATM-2 for a year now and twice a power tube has failed. First, an old stock Tung-Sol 6550 blackplate, which perhaps could not hold up to the modern amp. But, recently, I switched from reliable SED KT88s to the new Russain re-issue Gold Lion KT88s, and one of these tubes developed a leak after just less than 3 months use. A coincidence perhaps.

But it got me to wonder what the bias current and plate voltage for this amp are, as neither specification is published information. I've put these questions to two dealers and neither have been able to provide an answer.

I've also written AXISS, the distributor, to the same result--no answer.

Does anyone know the answer to these questions?
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I've owned my Air Tight ATM-2 for three years now. For the first two, I could count on one of the KT-88s not only failing, but the resistor catching on fire as well, on an average of once a month!

I finally sent the unit off to a gentleman by the name of Tom Tutay, owner of Transition Audio Design, 24 Elm Ave., S.E., Fort Walton Beach, Florida 32548 - telephone number (850)244-3041. Aside from creating his own brand of equipment, he is a certified Air Tight Technician, and he built a slow-start mechanism. It's basically a box with a toggle switch and he is adamant about not screwing around with the slow-start's settings! Anyway, I've been able to enjoy the ATM-2 and, for over a year now, have not had one single tube fail or, as in earlier instances, "blow up" on me, requiring the removal of the old, burned out resistor and soldering in of a new one. And another nice thing: Tom is a real gentleman in the truest sense of the word. He won't charge you an arm and a leg for his work, whereas if you were to send it back to AXISS Distribution, they'd ship it back to Japan and you might not see it again in months, plus it's highly unlikely that they would do anything like make a slow-start box.

Basically, you leave the power amp in the "on" position and use the toggle switch on the slow-start box to turn the power on and off. It's simple, relatively inexpensive, and you get your equipment returned to you in a timely manner. I've never had a more rewarding business relationship than I have with Tom Tutay.

-- Steve Welch
Call Tom Tutay at Transition Audio Design? I beleive he is in Florida or Miami. He works on AirTight gear and knows them inside and out.

you can google his name to get his contact info.