Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: stratomaster on September 14, 2024, 12:29:45 pm
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I accidentally discovered a great use for a no load pot I had in my stash. I added a Cut control (variable resistor and cap across the grids of the output tubes, ala Vox) to my Marshall Origin 50.
I wanted it to be switchable out of the circuit and found a no load 250kA pot in my stash. This fit the bill as at full the pot goes open--effectively out of circuit. No switches needed.
Additionally, the "dead" lug acts as a convenient eyelet to anchor the cap and wire connection to the opposing grid signal. This bonus feature is missing on a traditional pot arrangement.
Wanted to pass this discovery on to the community. Do with it as you please.
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It's not too tricky to mod a regular pot to do this.
Just remember to mark it up as such, to avoid confusion later :)
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It's not too tricky to mod a regular pot to do this.
How does one do this?
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It's not too tricky to mod a regular pot to do this.
How does one do this?
You get invasive. Pry the fold over tabs and disassemble the pot. Then cut away the very end of the track on the wafer. Reassemble.
Hadn't done a no load, but have done a 25k bias pot by just swapping the 10k wafer for one from a different pot.
You'll want to be careful as you only get one shot, if that, with the metal tabs.
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No load pot: several other video’s, search
https://youtu.be/a_rlkO0RRwI?si=vjknM990-NjkaNaz (https://youtu.be/a_rlkO0RRwI?si=vjknM990-NjkaNaz)
https://youtu.be/fBLp53iNCf4?si=rDB22VSOYMuTwCs2 (https://youtu.be/fBLp53iNCf4?si=rDB22VSOYMuTwCs2)