Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: MWaldorf on August 25, 2024, 05:52:17 pm
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Hi everyone. I've built an amp based on Sluckey's AO-44 Voxy Pee Wee and I'm interested in adding a master volume. Any clues on the best way to add one to an AO-44 based amp?
My schematic attached. Note that there's switchable triode/pentode pots on the EF86 and a bypass capacitor switch on the first triode after the EF86 (does this count as part of the phase inverter?) I also removed the NFB and RC filter on the OT primary.
Can I use a Vox style master volume (like the cut control but with no capacitor)? I've added it to my schematic in green.
Thank you so much for your help!
Mel
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Can I use a Vox style master volume (like the cut control but with no capacitor)?
That cross line MV sounds bad. Most guys don't like them.
You could try changing out the 1M grid leak R, that's on V2a, for a 1MA pot.
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Can I use a Vox style master volume (like the cut control but with no capacitor)?
That cross line MV sounds bad. Most guys don't like them.
You could try changing out the 1M grid leak R, that's on V2a, for a 1MA pot.
Funny, the only time I've tried one of this cross line MVs is in an modern AC15. I thought it sounded fine, though fine is not great. How wound the grid leak pot work? Would it be the same way as the cross line MV, ie outer legs to either end of where the 1M resistor currently is and the wiper connected to one of the outer legs? Would you include an inline resistor to have a minimal resistance there?
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Funny, the only time I've tried one of this cross line MVs is in an modern AC15. I thought it sounded fine, though fine is not great.
You can try it if you want, it works with out a cap. With the cap it's a cross line tone control.
How wound the grid leak pot work? Would it be the same way as the cross line MV, ie outer legs to either end of where the 1M resistor currently is and the wiper connected to one of the outer legs?
No.
You wire it up just like a volume pot on a Fender/Marshal/Vox etc.
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I finally got around to modding my amp. I used the Vox style master, and I also removed the tone stack and added a Vox cut control. I'm very happy with how it came out. Schematic attached. Thanks for all the help!