Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: catnine on July 15, 2011, 04:44:19 pm
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Yes it's on my AA764 champ build. In the photo attached I have the dpdt slide switch next to the input jacks and then there are three green wires going down to a pot to the left of the 12ax7 socket , to the left of that pot at the bottom of the chasis are the speaker jacks. This is the NFB switch and pot . Now I know you are supposed to keep the input section away from the output section and the yellow lead you see right in line with the green NFB leads is the Vol pot to the 12ax7. The chassis came with this slide switch cutout so I used it .
Now I don't hear anything as far as interferance or hum yet I do have the output section right there near the input or preamp section.
If there was an issue I should hear it correct? I can live without the adjustable NFB , the stock NFB is what I use and rarely the added 100k pot value in series to the stock 2700 ohm NFB resister.
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The NFB signal is a low voltage, lowish current signal by the time it hits the knee of the NFB voltage divider, so if its not bothering you, leave it where it is. I prefer to shield my signal cables tho (including ones that go from a pot to a grid pin)