The Acrosound Stereo 120 is a pair of ULII amps on a single chassis with a single power transformer.
I own one.
Originally they used KT-77s iirc. But there have not been any real KT-77s for a long time. I think people are making "new" KT-77 tubes now, but likely a good set of 6CA7/EL34 will do well. The biasing should be as per the tube manual for the given plate voltage... some variation with that is appropriate, assuming you have either a means of measuring the distortion or looking at the waveform with a 'scope.
Of course today you can look up the original output tube specs and compare to what is presently being sold/made and pick one that is closest to the original tube's specs/values.
One of the pots is (iirc) a "balance" pot, and is for making the positive and negative halfs of a sine wave clip at the same point (removing asymmetry).
I actually have a 120 schematic, but it is not scanned, and I am not sure *where* exactly it is, and have no way to scan it at present.
If you search online, you can likely find a copy of the schematic, I would expect.
_-_-bear
I own one.
Originally they used KT-77s iirc. But there have not been any real KT-77s for a long time. I think people are making "new" KT-77 tubes now, but likely a good set of 6CA7/EL34 will do well. The biasing should be as per the tube manual for the given plate voltage... some variation with that is appropriate, assuming you have either a means of measuring the distortion or looking at the waveform with a 'scope.
Of course today you can look up the original output tube specs and compare to what is presently being sold/made and pick one that is closest to the original tube's specs/values.
One of the pots is (iirc) a "balance" pot, and is for making the positive and negative halfs of a sine wave clip at the same point (removing asymmetry).
I actually have a 120 schematic, but it is not scanned, and I am not sure *where* exactly it is, and have no way to scan it at present.
If you search online, you can likely find a copy of the schematic, I would expect.
_-_-bear
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