Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => EZ Board postings => Topic started by: Geezer on June 18, 2005, 05:44:17 am
-
Hoffman Amplifiers
> Tube Amp Building - Tweaks - Repairs
> Fat Switch + More Gain
<< Prev Topic | Next Topic >>
Author Comment
LooseChange
Senior tube assistant
Posts: 224
(3/27/04 11:07 am)
Fat Switch + More Gain
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
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??
<< Prev Topic | Next Topic >>
Topic Commands
Click to receive email notification of replies
jump to: Tube Amp Building - Tweaks - Repairs (New)New Product Suggestions (New)Praises - Complaints - Suggestions (New)Buy - Sell- Trade (New)Archives (New)
- Hoffman Amplifiers - Tube Amp Building - Tweaks - Repairs - Hoffman Amplifiers -
Powered By ezboard® Ver. 7.32
Copyright ©1999-2005 ezboard, Inc.