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I never even considered that the three gangs were the three resistors for the phase shift circuit. Though now I can't imagine what else they might be. Very clever J M
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"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz -
I was just about to say what J M said, but with a 1-gang RA pot instead. (Much easier to find than even a 2-gang RA pot)Building a better world (one tube amp at a time)
"I have never had to invoke a formula to fight oscillation in a guitar amp."- EnzoComment
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Last time I looked, some guy in Hong Kong was selling 100k dual gang reverse log pots on Ebay. I bought a bag full of them, and I use them anywhere I need a reverse log.
I think varying all three stages gives you a wider frequency range, but it's very rarely done: even amp manufacturers have trouble sourcing 3-gang pots. A circuit like the state-variable oscillator could get you a much wider range anyway, if you were prepared to use an IC."Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"Comment
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Thank You Steve, but a 100k pot will only make setting the speed control a problem. It will be difficult to get the freq. correct, because the control will be too touchy.
With 100k (which is 3 times the required resistance) you will zoom by the required resistance before you know it.
Take Care
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