Somebody try a variable negative feedback on Hoffman Stout TMB

[100decibels]

Hello.
I built a Hoffman Stout TMB for a friend and put a switch on the NF and it makes noise if I remove  the NF. I previously built a few Fender Champ clones with variable negative feedback with good results. Anyone try it? Regards.

[sluckey]

Many people have put a variable NFB control on their amps. Works OK.

Try this... Put your NFB switch across R19. Open = NFB. Closed = no NFB. Any noise with this configuration?

Or you may be interested in a NFB switch and presence control like this...

     http://sluckeyamps.com/november/november.pdf

[SILVERGUN]

I built a Hoffman Stout TMB for a friend and put a switch on the NF and it makes noise if I remove  the NF.

Removing NFB increases gain and as a result adds some noise.
What kind of noise and how much?

[JPK]

I had it on an 18 watt plexi and it didn't make any "bad" noise when the NFB switch was off. Or on. When I started to play guitar through it, it didn't always sound that good but it wasn't the amp. 

[100decibels]

Finally I put in a 39k resistor with a 100k pot, the original NF resistor is 82k so in the middle I have this. A little hiss at maximum and not at minimum. Me too when i play the guitar it doesn't sound good but it's not the amp or the guitar.

[JPK]

Slucky's schematic had a list of suggested resistors based on OT tap. Not sure this will fix it but good to know.