DC idle current flowing thru presence pot for PI cathode

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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jjman
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DC idle current flowing thru presence pot for PI cathode

Post by jjman »

I'm looking at the Express presence pot and all the dc for the PI's cathode appears to flow thru it. Isn't that taboo? Is it a wire-wound pot?

I'm trying to draw it using a 5k resistor for the dc and a pot wired as a variable resistor for the 0.1u cap. I'm thinking the pot would need to be no-load or maybe a higher value to get similar results?

Anyone else ever ponder or remove the dc from that pot somehow?
If it says "Vintage" on it, -it isn't.
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Bob-I
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Re: DC idle current flowing thru presence pot for PI cathode

Post by Bob-I »

jjman wrote:I'm looking at the Express presence pot and all the dc for the PI's cathode appears to flow thru it. Isn't that taboo? Is it a wire-wound pot?

I'm trying to draw it using a 5k resistor for the dc and a pot wired as a variable resistor for the 0.1u cap. I'm thinking the pot would need to be no-load or maybe a higher value to get similar results?

Anyone else ever ponder or remove the dc from that pot somehow?
It's quite small actually. The biggest issue is a litte scratch when you turn the control. I've tried other topologies, I.E. placing the cap between the tail and pot, instead of after the pot. It just doesn't sound the same.
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FUCHSAUDIO
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Like Marshall

Post by FUCHSAUDIO »

The pot has a small DC voltage on it, just like a Marshall PI. It does scratch a little when you turn the pot, but I agree with Bob I, it sounds different if you do anything different to the circuit. Live with it, everyone else does....:)
Proud holder of US Patent # 7336165.
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