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Master Volume Tweaks?


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10/4/2004 12:29 AM
paulg
Master Volume Tweaks?
I installed a MV on my AC-30 clone. I used the Matchless, post PI 1MA pot type master. The problem I'm having is that it's pretty useless after about "2". It's a Audio taper pot. Any suggestions for getting a smooth increase in volume throughtout its rotation? thanks
 
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10/4/2004 7:44 PM
Matt
I built a cathode-biased, non-NFB amp and used that MV at first. I didn't like that MV and instead went with the dual-pot post-PI MV and liked it much better. I think Ken Fisher wrote about it and I've heard it called the "Rich mod" as well. I wish I could elaborate more (I will tomorrow if needed) but something just came up and I gotta go! HTH.
 
10/4/2004 11:01 PM
hasserl

I have that Matchless MV on a Clubman type build, it's okay but at volumes lower than about 9:00 it gets really buzzy, it looses a lot of the tone quality too. In another amp I put a version of the post PI MV mentioned by Matt, I followed Marshall's 2150 pre-amp schematic. From the PI coupling caps run the signal into the top of the pot, the wiper to the bias resistors/power tube grids, the bottom of the pot to ground. This does work much better than the Matchless MV, it retains much more of the tone and does not get buzzy. I used a 1M dual pot from Weber VST.
 

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