Futterman H3AA Output Transformerless Tube Amp Schematic

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mediatechnology
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Futterman H3AA Output Transformerless Tube Amp Schematic

Post by mediatechnology »

I have a neighbor with a output transformersless Futterman H3AA power amp.
This is a very unique cathode follower design.

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Futterman H3AA Schematic
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JR.
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Re: Futterman H3AA Output Transformerless Tube Amp Schematic

Post by JR. »

I vaguely recall seeing one at AES show back in the day but I seem to recall more glass bottles than that.

I bet it doesn't like driving 2 ohms. :D :D

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Re: Futterman H3AA Output Transformerless Tube Amp Schematic

Post by emrr »

I've never looked at one of these. I think I need a redraw to see that better. Definitely unique amongst that which I've seen.
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mediatechnology
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Re: Futterman H3AA Output Transformerless Tube Amp Schematic

Post by mediatechnology »

I forgot to post the Futterman Patent US3123789: http://www.waynekirkwood.com/images/pdf ... 123780.pdf

Figure 3 is a little more clearly drawn than the H3AA schematic.
I haven't read the text of the patent that closely but it looks like the 6LU8s are the output screen drivers which serve to provide a constant cathode to screen voltage.
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