Hello again , I hope that this is what it is called ( negative feed back ???) NFB . I see a variable pot in the middle of the circuit board of these VTLs which I have brought back from the dead. Replaced both Power caps in both amp , replaced suspect tubes in one and replaced a 20k resistor that was bad in the other . It seems "something" can be adjusted and I take it that it is for a balance of sorts ? Between the two banks of four 6550we tubes in theses mono blocks? Please educate me.
Now since an adjustment can be made , what would I be looking for voltage wise ( will be ac or dc) mv or volts. I see close to this pot are four diodes and a capacitor would this be a bridge rectifier associated with this pot?
As always thanks for the safety protocols working with tube amps. Luckily this amp has a negative insert for the negative probe so it is a one handed process probing into the circuit.
Thanks all
Now since an adjustment can be made , what would I be looking for voltage wise ( will be ac or dc) mv or volts. I see close to this pot are four diodes and a capacitor would this be a bridge rectifier associated with this pot?
As always thanks for the safety protocols working with tube amps. Luckily this amp has a negative insert for the negative probe so it is a one handed process probing into the circuit.
Thanks all
The trimmer adjust one section of the phase splitter because changing the tube (probably a 6350 or 12BH7) it can be possible that the drive signal to the power tubes are not same in amplitude.
To check correctly you need a signal generator and a THD analyzer to set at minum % the distortion for different level; it is a "trimming" setup
Walter
To check correctly you need a signal generator and a THD analyzer to set at minum % the distortion for different level; it is a "trimming" setup
Walter
Yeah , 6350 tube indeed. Well , I have neither of those testing apparatus so I guess I wont be doing any adjustments. Other than not functioning optimally are there any sonic negatives that are perceptible?