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Futterman

24.141.114.174
Posted on March 6, 2024 at 06:04:12
AJ
Audiophile

Posts: 533
Joined: February 24, 2001






Since the forum seems a little sleepy and there is some recent activity on Futterman- I thought I'd share a recent acquisition.

A pair of mint Futterman H3aa's after 40 years of sort of searching I ran into a great fellow enthusiast and we made it happen.

They have been sitting for a few months as life has definitely got in the way but I hope to get them singing soon.

Most of my time has been weighed down with the refurbishment of my Beveridge direct drive amps-including new boards. I have them working but they are definitely oscillating.
It has been quite elusive. But I have some thoughts and have had some support from members on DIY and a email or two from folks here.

Terribly frustrating as the the Bevs actually sound so good. I am glad I have my model 3's running with DD and these 2sw-2's are a "project" I may start another thread. In the meantime any suggestions welcomed!

 

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RE: Futterman, posted on March 6, 2024 at 09:30:57
33dot33rpm
Audiophile

Posts: 79
Location: Nor Cal
Joined: June 8, 2006
 Hi AJ, your pair of H3aa looks awesome!!! Please keep us posted on their progress.

 

I just saw that you are having problems with Beveridge amplifiers, posted on June 22, 2024 at 19:20:22
Lew
Audiophile

Posts: 11011
Location: Bethesda, Maryland
Joined: December 11, 2000
 First, those could well be the very same H3aa's that I once owned. No way to be certain. I sold them to a guy who drove to DC from NYC to pick them up, about 25 years ago or more.

Second, I have extensive experience debugging the 2SW amplifiers shown in your photo (which is to say making them work without oscillating). If you haven't yet fixed your problems, I would be glad to help.

 

RE: I just saw that you are having problems with Beveridge amplifiers, posted on June 24, 2024 at 05:17:07
AJ
Audiophile

Posts: 533
Joined: February 24, 2001






Thanks Lew,

You and I have been conversing by email a few times regarding these.

Your trick to add a CC resistor between the cathode and heater also was helpful.

For others, the transformers in both Beveridge amps were electrically leaking and I had to design new transformers. This time separating the the HV from the filaments and pre--resulting in 2 transformers Solving the problem.

Some before and after pics.

 

RE: I just saw that you are having problems with Beveridge amplifiers, posted on August 17, 2024 at 14:39:40
Lew
Audiophile

Posts: 11011
Location: Bethesda, Maryland
Joined: December 11, 2000
 AJ, On that same one of my two amplifiers that was oscillating, I not only inserted that 100R buffer between the cathode and the filament on (I think it was) V202, but I also installed a separate 36V transformer specifically to replace the filament supplied to that one tube (V202) from the Bev PT. In fact, bypassing the filament supply from the main PT to V202 (one of the three separate 36V filament supplies that come off the main PT, as you know) did the most to reduce oscillation. But the coup de grace for the oscillation was adding that 100R resistance. My other amplifier has no such problems, I think because somewhere in its life before I got it, it received a new PT. Certainly it's newer than the one having problems. Yes, I agree there seems to be leakage between the HV tap and especially this one of the three filament supplies.

 

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