Sick Ghia (I Think)

[pdf64]

Using a 2mV input and connecting the probe to the plate of the Power Tube here is what my forms looked like

Putting a probe on an output tube plate can cause weird things to happen.
What does the wave look like at the OT secondary?
Pete

[jon]

Using a 2mV input and connecting the probe to the plate of the Power Tube here is what my forms looked like

Putting a probe on an output tube plate can cause weird things to happen.
What does the wave look like at the OT secondary?
Pete

Pete you were correct, Moving the probe fixed the notch in the wave.

After spending some quality time with the amp yesterday I have found an interesting problem. My Phase inverter is out of balance. My plate voltage on one triode is about 2vdc lower on one side than the other. a quick check with the scope and I confirmed that one have of the PI is stronger than the other by about a 1/3. I carefully checked all my plate and grid resistors to make sure they match, and still no change. I also changed the tube and had a similar result. I am tempted to put a pot on one side of the PT to balance it out but I shouldn't have to. Can anyone think of a reason why I would have such an imbalance.

[Structo]

A LTPI is always a bit out of balance.

Dumble amps usually have the input side about 5-6v higher than the other plate.

But, the easiest route is to just roll some tubes through that socket and choose one that sounds the best to you.

Also if you install a trimmer it should go across the plate resistors, not on just one side.
This can be a bit tricky to adjust as it takes just a bit for each adjustment to take hold.