Fat Switch + More Gain

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LooseChange
Senior tube assistant
Posts: 224
(3/27/04 11:07 am)
 Fat Switch + More Gain
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 I installed a "FAT" switch. Standard arrangement: Switching a 22uf cathode bypass across the existing 3.3k/.1uf bias on half of a 12AX7. I have a 100k across the switch. It works perfectly.

BUT, I want to add more gain: I added a 1.5K in parallel with the 22uf. Problem is I get a bump noise every time I switch it in or out.

Got any ideas to stop the bump noise??

Thanks!!
 
PHATamps
I only work on tube amps
Posts: 428
(3/27/04 11:25 am)
 Re: Fat Switch + More Gain
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 That's a pretty radical bias shift. With the added resistor you're going from 3.3K to about 1K. If you want wind up with the standard 1.5K/22uF, replace the 1.5K you added with a 2.7K. This ought to reduce the bump you're hearing, but may not eliminate it.
 
LooseChange
Senior tube assistant
Posts: 225
(3/27/04 3:21 pm)
 Re: Fat Switch + More Gain
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 Actually, I tried a 3.3k and a 2.2k. The bump was still there. So I figured I'd go for over the top.
I guess there is NOT a scheme to get that "bump" out of there??
 
 
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