Liverpool values question

[Tdale]

The Liverpool has a 10K cathode resistor on the last preamp tube, and no bypass cap.

What does this do to the circuit? I always thought that a high value cathode resistor, makes the grid more negative (relative to the cathode) which again means low gain.

Or does it make the signal asymetrical, with much distortion?

Tommy

[skyboltone]

The Liverpool has a 10K cathode resistor on the last preamp tube, and no bypass cap.

What does this do to the circuit? I always thought that a high value cathode resistor, makes the grid more negative (relative to the cathode) which again means low gain.

Or does it make the signal asymetrical, with much distortion?

Tommy

I would love to see a set of scope pic's with several drive levels at each stage of the Express. The lash up at V3 has been called the "clipper" stage by others. One effect of not bypassing the cathode resistor is regenerative feedback (degenerative?). I think it acts as a limiter but I've never taken the time to actually follow the signal through the amps with the scope. Good project for one of these Saturdays.

[dartanion]

Cold clipping stage or starved cathode.

[doctord02]

I though some one here had already made a web page with screen caps of a scope showing each stage of a wreck... as I recall it clearly showed the progression of clipping - starting at the power tubes and proceeding back up the circuit...

At anyrate, I've seen it somewhere on the web...

[xk49w]

The Liverpool has a 10K cathode resistor on the last preamp tube, and no bypass cap.

What does this do to the circuit?

It makes a relatively low distortion gain stage with a gain approximately equal to the value of plate resistance divided by cathode resistance, in this case a gain of ten.

[tonehound]

I had this page bookmarked. It shows some Trainwreck Express Clone Oscilloscope photos.

http://home.polstra.com/amps/wreck1/scope/