Potentiometer Wattage question

[Soulchief]

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

[d95err]

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.

[Latole]

Any pot will do the job.

[pdf64]

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.

[Soulchief]

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?

[pdf64]

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.

[Soulchief]

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..

[tubeswell]

… 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

[Soulchief]

Thank you to all thanks helped with reply..

Ordered up a Pot this morning!