Hi all
I will have to look at the notes I made, however it did have NFB but the thing was quite clever as the "bias" pot's were each ganged with a switch, (just as a volume or tone control would be with a mains switch), the switch would shunt the NFB when you wanted to increase the bias. Same also applied to the AC drive balance, (I will call it), with both controls turned off it operated as a normal UL amplifier.
I did find out that it was a manufactured item that had been re cased, (I had a friend re-re-case it with two cheap 60W 5" "soundlab" twin cone drivers to replace the knackered 10" job
) German made, (Kohler?) as a universal instrument amp actually, not just for guitar.... As you know Peter, I was persuaded to sell it. 
Thanks,
Amie.
Kalee20 Wrote:Interesting! Did the amplifier have NFB around it all - which would have reduced the distortion up to a point, but also made the onset of severe distortion more acute? Or was it open-loop? I'd guess the latter.
I will have to look at the notes I made, however it did have NFB but the thing was quite clever as the "bias" pot's were each ganged with a switch, (just as a volume or tone control would be with a mains switch), the switch would shunt the NFB when you wanted to increase the bias. Same also applied to the AC drive balance, (I will call it), with both controls turned off it operated as a normal UL amplifier.
I did find out that it was a manufactured item that had been re cased, (I had a friend re-re-case it with two cheap 60W 5" "soundlab" twin cone drivers to replace the knackered 10" job
) German made, (Kohler?) as a universal instrument amp actually, not just for guitar.... As you know Peter, I was persuaded to sell it. Thanks,
Amie.
