I have problem with tube amp Orange OR120.
Got it in non working condition, power section is refubished, all ok.
There are only 2 tubes on output, two of them are pulled off, impedance is set appropriately, one level lower.
Amp starts hard clipping (neg.side only) at low input.
Inverter (12ax7) is concertina/cathodyne, known as may be problematic.
Schematic is from early 70', as is seen on the photo.
Anyone with idea where to start?
It looks like too low bias in inverter?
Resistors and caps around inverter and power tubes are new.
Output tubes are new Tad EL34, running at 500vdc at plates, bias is set to 27ma.
Here is scope screen and schematics:
Got it in non working condition, power section is refubished, all ok.
There are only 2 tubes on output, two of them are pulled off, impedance is set appropriately, one level lower.
Amp starts hard clipping (neg.side only) at low input.
Inverter (12ax7) is concertina/cathodyne, known as may be problematic.
Schematic is from early 70', as is seen on the photo.
Anyone with idea where to start?
It looks like too low bias in inverter?
Resistors and caps around inverter and power tubes are new.
Output tubes are new Tad EL34, running at 500vdc at plates, bias is set to 27ma.
Here is scope screen and schematics: