Just curious, did Dumble ever use a post-PI master?
I've used Ken Fisher's design using a dual 250K pot with the bias running in it with great success, but not in a Dumble circuit.
Post PI MV
Moderators: pompeiisneaks, Colossal
Re: Post PI MV
I couldn't tell you if he never used one... 
But in the amps that I know about, there was none.
But in the amps that I know about, there was none.
Re: Post PI MV
Actually IMHO a Dumble with PI distortion sounds terrible. I have a low power Dumble with 2x6V6 and the best tones out of it are when the PI is clean and the 6V6's are smoking. Click in the ODS side and that thing just sounds like heaven. I once pushed the PI into distortion and I thought something was broken.
Re: Post PI MV
Somebody at TGP had andy add PS or VVR to his Fuchs. I recall that he liked it a lot.
Re: Post PI MV
Has anyone ever tried the Trainwreck Type II Master volume in a Dumble style platform?
It works a bit different than your average MV, as it replaces the 220k bias resistors with a dual 250k pot.
It works a bit different than your average MV, as it replaces the 220k bias resistors with a dual 250k pot.
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David Root
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Re: Post PI MV
That's the one I was talking about. It is a great design I think. From what I see above, maybe not right for a Dumble circuit.
However, I have one in this 100W 2x8417 amp, I recently took out the reverb and replaced it with a #124 ODS circuit. BUT I also have a pre PI MV same as Marshall/Dumble immediately before the PI.
So that may explain why it sounds better with the post PI MV full up ie out of circuit. I can still overdrive the PI from the V1 vol pot with the pre PI MV full up, well it's either the PI or the 8417s.
How it got to be like that is a long story....still in progress as I am having trouble getting the ODS where it sounds good, too much harsh artifacts when cranked.
Then again, the PI is a straight Marshall/5F6A so maybe I need a BluesMaster OD setup??? Did I mention the preamp is i6SL7, not 12AX7. This could go on for ever......
However, I have one in this 100W 2x8417 amp, I recently took out the reverb and replaced it with a #124 ODS circuit. BUT I also have a pre PI MV same as Marshall/Dumble immediately before the PI.
So that may explain why it sounds better with the post PI MV full up ie out of circuit. I can still overdrive the PI from the V1 vol pot with the pre PI MV full up, well it's either the PI or the 8417s.
How it got to be like that is a long story....still in progress as I am having trouble getting the ODS where it sounds good, too much harsh artifacts when cranked.
Then again, the PI is a straight Marshall/5F6A so maybe I need a BluesMaster OD setup??? Did I mention the preamp is i6SL7, not 12AX7. This could go on for ever......