Teach me a little something about NFB in a Deluxe Reverb

[mort]

Finishing up a Deluxe Reverb build and wanted to toy around with the NFB. I've seen people put switches to open and close the nfb but what about putting a switched pot on it that's off at zero? I'm sure it's been done but it's not searching well for me. What range resistance on the pot would be most useful? 5k? 1m? Is the NFB effectively not connected above an approx resistance?

And just double checking that it would be drawn like this. Seems simple enough...

[Enzo]

Switch. Just disconnect the NFB wire, and listen to the amp, Now touch the wire back wher it was, as a switch would, and see if the difference intertests you.

Pot. Get a pot or two from your drawer. Say 100k, it doesn't matter. Clip it in series with your NFB wire. Turn it up and down. Note what it sounds like at zero ohms - should sound like stock amp. Now turn it up, listening for the effect. How high is it turned when you no longer hear change? At that point, stop, unclip the pot and measure the resistance. That would be the resistance the real pot should be. Clearly if it is 12.7k or something, you go with a common 10k or whatever standard value you have.

[mort]

I will do just that!

[Dave H]

You could also do it like this - Disconnect the 820 feedback resistor from the speaker. Connect a 1k pot in parallel with the speaker. Connect the wiper of the pot to the disconnected end of the 820. That will give you the stock circuit feedback, zero feedback and all points inbetween without using a switch.