Tube Amp Archive

Isn't 2nd order distortion the kind where the top and bottom of waveform are different? So its the transformer that gets rid of it and not the class of operation of the power tubes. Any 2nd order created by the preamp gets amplified normally. In theory perfect class A amp would not create 2nd order ...

The cathode of the tube is like a ground for AC since it's cathode resistor is bypassed with a large cap. The output impedance of the stage and the capacitance of the cap (from plate to cathode) form a low-pass-filter for the signal coming from the tube. You can use a RC-filter calculator to calcula...

Could be made to work with relays, although a relay for switching HT might be expensive/big/hard to find.

Have you tried the amp without the switch arrangement? Might be something accidentally touching or a faulty switch...

Hey, are you sure when you use the buffer that your input's grid still has a ground reference, ie. a resistor to ground? Maybe a bad solder joint on the 1M input grid leak or no resistor at all? It would work with just the guitar but not with a buffer that has an output cap and no resistor to ground...