Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Soulchief on November 08, 2022, 02:02:50 pm
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Hello all,
Trying to fit a ‘10K-A Mid Pot’ into a DIY Fender Champ with semi tight spacing and not enough room to fit a standard 24mm pot.
Looking at 16mm Alpha Pots, with a ‘Wattage Rating of .06W’, is that too low for Tone Pots on Fender Amps?
Linear 16mm Alphas are .125W. Not sure why Audio/Log are only .06W...
And of course the larger standard pots are .25W.
Would the .06W Rating be safe in the case of a Mid Pot?
Thanks for your help
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16mm Alphas are fine for any normal use in tube amps. It’s just signal voltages with very little current. You’ll find 16mm pots in most modern amps.
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Any pot will do the job.
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The only typical valve amp application where a 60mW pot would struggle is the 50k trem intensity control of a black or silver panel 2 channel Fender.
Based on overdriving it heavily like Ted Nugent, which might result in prolonged periods of a roughly 60Vrms signal across it.
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Thanks for the help and with all your answers agreeing it will be ok I will throw one in.
Curious for knowledge, what would be a sign that a pot is not keeping up or struggling? Just stop working?
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I suppose there might be somewhere along the track it burns out.
To speculate in detail how that would play out, you need to specify whether the pot is wired as a pot or a variable resistor type of midrange control.
Whichever, there would probably be a setting that lifted the tone stack, big increase in signal level, tone controls disabled.
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Ok yes that makes sense.
In this case I guess this will be set up as a Variable Resistor Mid Pot as in AB763’s:
Bass Pot Lug 1 > New Mid Pot Lug 2 > .047 Tone Cap // Ground Mid Pot Lug 1
This is where the .06W Mid Pot is in question - which answers seems to agree OK..
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… with a ‘Wattage Rating of .06W’, is that too low for Tone Pots on Fender Amps?
Figure out the actual* application I.e.;
Voltage drop across the pot divided by the resistance of the pot = current through the pot. Current through the pot times voltage across the pot = power dissipated by the pot. If this sums to 0.03W or less, a 0.06W rated pot would be fine.
* a mid pot in a Twin Reverb as no DC across it, and in terms of signal voltage it’s only a handful of mVac. So you’ll be fine
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Thank you to all thanks helped with reply..
Ordered up a Pot this morning!