The Amp Garage

For the sake of the exercise you can leave everything in place. If it were permanent it would make sense to attach a grid leak before the 33K grid stopper. Otherwise it creates a voltage divider but it would only be a roughly 7% drop in signal to use a 33K/470K divider. It wouldn't be a noticeable d...

Sure it's fine but isn't just throwing up grid stoppers only going to mask the problem?
I wouldn't imagine the treble tamed by a larger grid stopper would prevent blocking distortion normally caused by excessive current or too large of an incoming signal.

If I was experiencing this and I needed to begin troubleshooting I would be looking at a schematic of the circuit to see where the issue could possibly be coming from. I know that's not what you want to hear but I sketch out everything I build or modify as it's the only way to keep track of the sign...

I replied in the thread over at gear page. Sounds like you're missing a grid leak somewhere in the preamp or a stage is being driven too hard.

56K grid stoppers on the output are massive!
Usually people go lower to 1.5K.

I haven't noticed a difference when moving the output cathode grounds. I just leave them where they are and focus on the preamp grounding and making sure the power supply chassis ground is far away. So basically I am following the idea of the Larry scheme but I leave the cathodes and heater CT alone.

Have you measured this? I don't see how it can happen. Yes, this has been measured and observed. This is not exclusive to Superlead circuits. Observe your current meter when biasing with probes connected to each output tube and you can also see this on your oscilloscope. When driven into distortion...

how about 4 el34s with a very unmatched driver that redplates v4-v5, but not v6-v7 (a common scenario) I'm not sure what you're getting at. Yes, in a Superlead circuit V4 and V5 draw double the current as V6 and V7 when the power amp is driven into full distortion. The red plating is a sign somethi...

I reached out to Engl not too long ago and they provided me with a full schematic of one of their old power amps. I was surprised at how courteous and prompt they were to hand it over. Is the sound you are describing rising a falling or is it a steady pink noise type of sound? The circuit in the sch...

I can't see where this would have any good outcome. A 100W EL34 based transformer has a winding ratio to suit around a 1.7K primary impedance. Dropping two tubes creates a mismatch since two EL34's want to see a winding ratio suited for a 3.4K primary. That alone turns your 8 ohm tap into your 16 oh...

Would be interesting if it could be pulled off. The signal flow, impedance matching, and amplification factor is only half the battle. For example, pull six 6L6GC's from a Triple Rec and the heater secondary just had close to 8A unloaded from it. That's provides a necessary voltage drop to keep all ...