JCM 800 2204 Self oscillation problem

[Phil_S]

Why bother with all of that? Add a presence control pot instead. Then your NFB adjustment is fully variable and there are not so many parts.

[Reeltarded]

Think about adding a 250k pot with maybe a.. 27k stop instead of all the switching. Then you get subtle to stupid with the turn of the knob. Presence and resonance plus that means you can mix in sizzle and thump on a moving curve.. this works reaaaallyyy well.

[bpamps]

Thanks guys... I had swapped the wires feeding the output tubes. Creating almost the same effect except that I couldn't even normalize the amp with the NFB circuit hooked up.

It's easy enough to do. At least that's what I'm telling my self today to save some pride points.

The funny thing is... the amp sounded a little different, but not bad the other way. With the NFB circuit completely out that is.

[iknowjohnny]

Why not use a pot for NFB instead of a rotary? Simpler, cheaper, infinite control. I use a 220k with a 100k resistor in series with the pot off the 8 ohm tap. I also modded the pot so it's no load and at the end of it's travel where it's at minimum NFB it then goes to zero NFB.