jdduffield
Active member
What would happen if I changed the 100k pot to a 25k pot for the output volume control? (On the Muroidea)
Muroidea 100k Volume Pot Sub
- Thread starter jdduffield
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jdduffield
Active member
Also, what do you all use to shorten the shaft on a potentiometer? Is there a way to sand it down or cut it?
jessenator
Well-known member
It would make the volume far more "sensitive," if that makes sense--making the output ceiling higher. In a visual comparison based on knob position (weird, because they're log/audio tapers), but 12 o'clock on a standard Rat-a-like (A100k) is about the same as 9 o'clock on a A25k version---this is on my 5W tube amp---to my ears, anyway.
With home tools I personally wouldn't do it. Can it be done? Sure. Sanding might take a bit. Others might recommend something like a dremel, but I personally would just buy the correct one. I'm thinking of shavings getting into the pot, on the wiper/carbon strip.
I'm guessing you have a split/splined shaft one you want to get down to smooth shaft's height?
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jdduffield
Active member
Yes. Trying to get this knob closer to the enclosure.
Also, to avoid shavings, what if I install it into a spare enclosure while sanding?
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jimilee
Well-known member
You could install another nut on the other side of the enclosure, or a few more washers. My guess is it’s a splined pot. Not sure how well those will cut.
jessenator
Well-known member
As far as sanding, only other thing---now that I'm thinking about it---is putting too much pressure and/or lateral shear on the pot stem. I have no idea if it would cause actual damage, torquing that around, but it's just on my mind. I would tape up the pot with some masking stuff and go slow and gentle.
Here's no washers vs 4 washers on the other side of the enclosure.
Any more than that and you'll might have trouble threading the nut
But as far as value, yes, buy the correct value.
edit: another thing to consider is how wide and deep the "skirt" on that knob you've chosen is. Using washers is less destructive than sanding, and might let you see if there will be interference. Getting some knobs too low will just cause them to bottom out, so to speak. Haven't tried guitar-type knobs on a pedal myself, so I don't know.
Here's no washers vs 4 washers on the other side of the enclosure.
Any more than that and you'll might have trouble threading the nut
But as far as value, yes, buy the correct value.
edit: another thing to consider is how wide and deep the "skirt" on that knob you've chosen is. Using washers is less destructive than sanding, and might let you see if there will be interference. Getting some knobs too low will just cause them to bottom out, so to speak. Haven't tried guitar-type knobs on a pedal myself, so I don't know.
jdduffield
Active member
I didn’t even think about adjusting the other side with more washers or another nut. That will save time. I’ll go that route.
Feral Feline
Well-known member
You'd have to be purdy-dang careful cutting/chopping/filing/sanding a splined-shaft knob so as not to weaken the tangs of the split shaft!
Once shortened, you'll have less splined contact area for the knob to adhere to give that the splines don't go all the way down to the threads on most such type potentiometers I've seen.
IF you have room on the threads, I'd add a nut to the INSIDE of the enclosure to set the height of the pot (in addition to the external nut, of course);
even if you've enough threads, if the pot is a PCB-mounted one, you may not have enough internal height with a 1590B, though a 1590N1 would work.
If the pot is offboard wired to a smaller PCB, that would increase the chances of successfully adding the "locking-nut" to the inside...
DOH, [edit: JIMILEE & ] Jessenator beating me to the punch, again AND with graphic illustration!
Once shortened, you'll have less splined contact area for the knob to adhere to give that the splines don't go all the way down to the threads on most such type potentiometers I've seen.
IF you have room on the threads, I'd add a nut to the INSIDE of the enclosure to set the height of the pot (in addition to the external nut, of course);
even if you've enough threads, if the pot is a PCB-mounted one, you may not have enough internal height with a 1590B, though a 1590N1 would work.
If the pot is offboard wired to a smaller PCB, that would increase the chances of successfully adding the "locking-nut" to the inside...
DOH, [edit: JIMILEE & ] Jessenator beating me to the punch, again AND with graphic illustration!
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jessenator
Well-known member
Nah, Jimi got it first 
I just aped it and went over to my bench to try it out.
I just aped it and went over to my bench to try it out.
Feral Feline
Well-known member
Too many people posting while I'm pondering the problem... if only I couda posted faster...
jdduffield
Active member
That did the trick! Thank you!
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jimilee
Well-known member
Absolutely, glad it worked out. I do this for toggle switches and the stomp switch. I use a nut so it doesn’t stick out as far.
