prs volume and tone controls

[KB9KXH]

I just got a used prs and the volume control has only a slight effect until its up to about 8 then from about 8 to 10 it seems normal, also the tone controls seem to have little or no effect, what causes this and what is the remedy?

[Chuck H]

Have you had better luck with another guitar using the same gear? It could be the way the signal chain is setup. Otherwise, it's hard to say without looking inside and checking how things are wired. Did you buy the guitar untested? Or did it work correctly through another rig at the time of purchase? When you say that the volume control has only a slight effect, does that mean it doesn't turn the guitar up or it doesn't turn the guitar down? Do the screws that expose the electronics look as though they have been removed and reinstalled (you can usually tell when a novice has worked on a guitar). It's possible that your wiring is just plain wrong.

[KB9KXH]

I have used the amp with other guitars and it did not exhibit these quirks. I bought the guitar off ebay and it had not been opened up before, i opened it and the wireing look to be intact, i have not tested the caps or pots yet because i cant quit playing it The volume control has a little effect but it seems like it is an audio taper and should be a linear taper. In the next few days i will get the numbers off the parts and look them up but what i was wondering is if maybe a shorted turn in one of the pickups could cause this. The sound is ok but its like im compressed at the upper end of the volume control, if i turn it down much below 7 or 8 it gets extremely quiet compared to all the other guitars i have had.And the tone control has almost no effect, just barely perceptible. I guess i will know more when i check the pots with an ohm meter and the caps to see if they are within tolerance.

[Chuck H]

A drawing or other diagram of the wiring inside might be helpful. Shorted turns on a pickup MIGHT demonstrate unusual loading. The differential between the proper pot value and ANY pickup should negate that beyond any audible difference in taper. That, and it's not likely ALL the pickups are shorted in the same manor. So the problem would be switch position dependant. Pickups are emminently more likely to go open rather than short. It may be a wiring error of some kind. If, that is, there is anything actually wrong at all. If, for example, this PRS is a humbucker loaded guitar, and all you've ever used before are single coils, the basic difference in tone may be throwing your perceptions off a bit.

[SWEINC]

one possibility you may want to consider is the volume pot taper. All audio pot tapers are not the same. In a linear pot you have one possible taper which is an equal change in resistance per degree of rotation. But all audio tapers are not the same. You may have seen pots that are labeled 100k 15A. That means it is a 100k audio taper pot that when set to 50% of its rotation it will measure 15% of its resistance (15k). It may say 30A ,20A etc. Therefore some audio tapers will compress the usable area of the pot rotation into a smaller area of rotation than others. You might try measuring your pot at the halfway point and seeing if you can ascertain whether a different audio taper would suit this guitar better.

[KB9KXH]

all audio tapers are not the same. You may have seen pots that are labeled 100k 15A. That means it is a 100k audio taper pot that when set to 50% of its rotation it will measure 15% of its resistance (15k). It may say 30A ,20A etc. That is it, thanks for the help

[Chuck H]

Yes. If you play clean to clean-ish most of the time you might be best served by a "faster" taper. I play with a bunch of gain so I like an A10 taper. It allows me to use the volume on the guitar as a distortion control. PRS guitars have been gaining favor with a lot of high gainers. So they probably have a pretty slow taper. Unless this PRS has similar pickups to your other guitars AND those other guitars use a linear volume pot, I wouldn't jump straight to a linear pot. The taper specs for audio pots aren't always available though. Bourns are A10, Alpha are A30 up to 250k, A25 for 500k and A15 for 1M (IME). I've seen CTS reported as A15 but I can't speak from experience. Maybe test the pot on a guitar that has similar pickups and the range you like. You will need to disconnect it. With the pot up half way, measure the resistance across the outer lugs. Then measure the resistance from the CT to the left lug (looking at the back) and determine the percentage of resistance as it relates to the overall resistance. That's your "A" number. Unless it's 50%. Then it's linear. FWIW sometimes a capacitor or a resistor/capacitor circuit is used across the CT and left lug as a taper correction/treble correction circuit. Duplicate this if it's present on your favorite guitar. I think PRS uses a 180p cap stock.