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

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.

@markusthenaimnut - you can email us at [email protected] and provide us with the relevant information. If your amp uses the 6FL6 we have plenty. We have some of the PL tubes as well.

Of the two H3s we bought, one was made by Harvard and the other by Tech Electronics. Both were much more reliable than the NYAL version. If you go back to some of Futterman’s published schematics in engineering journals you will note that they were of low power design. Futterman got caught up in the power game when the H3 was designed and it’s no coincidence that reliability issues started popping up with the increase in power. Roger’s design will be in the neighborhood of 40 watts pentode/25 watts triode.

@tomic601 - Yes Roger was UVA undergraduate, then a year at Stanford. While your offer is appreciated, Roger became dismayed at what they were teaching at UVA these days and also became disenchanted that the young engineers to be were not interested in audio circuit design. As such he decided not to donate to any academic institutions. He instead has made other plans for his journals, recorded interviews (including Saul Marantz and Futterman among others), rare and exotic tubes, antique electronics, and intellectual property.

@ndevamp - yes your help would be appreciated, I will email you to discuss.

I will look for them but recently I saw the hand typed instructions Julius provided for making adjustments to the H3. This was one of the areas where Roger simplified the design, using a 6 position switch and meter so one could easily take readings and adjust accordingly.