Futterman. Jump in? Or, not so fast...

Roberjerman - Thanks for the comment. I had sent you a message a day or two ago and it appears you might not have noticed. Can you tell me how many hours you get out of a set of tubes on the H3aa's? I've read somewhere that they will go 10,000 hours, but I'm not really sure how many hours the current set has on them. The  amp comes with test results for all 12 tubes. But I can't imagine not buying a back-up set of tubes, which will cost quite a bit. How often are you having to re-tube your amps?

Yes we have some of the tubes for the Futterman amps. We need to know the specific tubes and amp so we can check the inventory. Prior to his passing Roger designed a new OTL circuit based on Futterman's work. There was a point in the prototype development where Roger was a bit stumped as to why he was getting some oscillation from the amp. So he purchased a Harvard H3 in hopes of figuring out the issue. Turns out that in the H3 schematic Roger was using as a guide, Futterman "conveniently" left out a critical design component which was easily seen when you opened up the amp - the plethora of ferrite beads in the circuit. That solved the issue.

Once manufactured we intend to publish Roger's design philosophy for this new amplifier. It uses a significantly less number of parts, not nearly as many ferrite beads (Roger used a neat trick to solve for that), has improvements in the circuit, and is simpler to set up than the Futterman. Roger's appreciation for Futterman's work includes his recorded interviews with the man that contain a wealth of knowledge, as well as multiple files on various Futterman designs, some that were given to him by Julius himself.

clio09 - cool. 
So, if I were to send you info about the tubes I need, might you be able to provide several which would match the test data of the tubes already in the amp?

Damn @clio09, now you've gone and reminded us of why Roger's passing is such a loss to us all. ;-(