VVR (cathode bias) suitable for preamp fixed bias amp

[guile]

To be sure I attached a picture. Should I interrupt the lead there?

[martin manning]

It's difficult to tell what you have there since it's a non-standard layout, and I don't want to guess. Do you have a schematic for this amp as-built?

[guile]

It's difficult to tell what you have there since it's a non-standard layout, and I don't want to guess. Do you have a schematic for this amp as-built?

Hope this helps!

[martin manning]

See attached. In either case I Think it would be a good idea to put a diode (1N4007) in front of the VVR input.

[guile]

Again thanks Martin.
What would be the orientation of the diode?

[martin manning]

Banded end (cathode) towards the VVR input.

[guile]

I think you might want to try it both ways. Basically the difference will be PI distortion vs. effect on the negative feedback loop.

I'm interested to know what the difference in sound and feel there is between PI distortion and effect on the negative feedback loop. Could that be described in any way?

[guile]

I think you might want to try it both ways. Basically the difference will be PI distortion vs. effect on the negative feedback loop.

I'm interested to know what the difference in sound and feel there is between PI distortion and effect on the negative feedback loop. Could that be described in any way?

I did some testing and decided to go with only regulating the preamp. The difference is very noticeable not only in a warmer, fuller sound, but also in a more compressed feel and attack.

[martin manning]

Great! Sometimes the best course of action is to just try it and see, especially if the experiment is an easy one.

[guile]

It's hard to describe the amp now but I think 'juicy' about covers it XD

Downside is that I have scratshy pots and true bypass pedals pop when engaged. Is there anything that can be done?

[martin manning]

Guitar pots or amp pots? Which ones?

[guile]

Volume of amp, volume of guitar and pickup selector.
Only noticeable when voltage is regulated very low.

And very nasty pops in true bypass effects.

[martin manning]

These are common issues with VVR at low voltage settings. You'll have to block DC (grid current) from the pots and the input as shown, and maintain the ground reference.

[sluckey]

Why would you replace that 1M with a jumper? Doing so makes J1 useless.

[martin manning]

Oops! Just take it out. Thanks for catching my mistake!