CTS Pot roll off

hello everyone,
i just finished building my partscaster tele. everything works great, except for the volume pot. it's a 500k cts audio pot. i have 2 seymour duncan 59's in the guitar. when i play through the overdrive channel of my amp the volume rolls off gradually and smoothly, but playing through the clean channel the volum rolls off quickly... when i turn it down from 10 the volume disappears steeply ... around 6 and the sound is pretty much nothing below 6. does anyone know why this might happen?
thanks!

Well there's nothing wrong with your ears or your rig; what you're noticing is a function of the type of potentiometer used as a volume control. "Audio" refers to the "taper" of the pot, or how fast it rolls off when you back off the volume knob. The other common type of pot is "linear" but our ears don't respond to changes in sound pressure levels that way. Our ears respond more to a logarithmic curve, so once things begin getting louder they have to get a lot louder before we notice a difference. As a result an audio taper pot won't do much from 1 to 5 but does quite a lot from 8 to 10 on the dial where the log curve is steeper. If you've got higher output pickus driving the amp and some distortion dialed in, then the amp will notice the change as soon as you drop off from 10 to 9 or 8 (and for my rig that's too abrupt so I'm not crazy about audio taper pots in humbucker equipped guitars).

Gibson (at least for production GibsonUSA guitars, not for Custom Shop Historics) uses linear pots for volume controls and audio taper for tone controls; Fender uses audio all around.

With higher gain settings on the amp you might appreciate one type over the other. There's a third option made by CTS for RS Guitarworks which they sell as a "Superpot" which is not linear but not as abrupt as an audio taper pot.

viz,
thank you! i'll have to try a linear pot next time then. but for now as long as it's not broke i'm ok with it. this is the first time i did all the wiring myself, and soldering is definitely not my specialty. when i first plugged it in i kinda expected to hear all sorts of electrical buzzing or that nothing worked. i was beyond thrilled to find that not only did it work but that it is totally quiet. thank again. jim

On a related note, where do you find linear cts pots? Stewmac doesn't seem to have them.

On a related note, where do you find linear cts pots? Stewmac doesn't seem to have them.

Axesrus

http://www.axesrus.com/axeElectronicsPots.htm#CTS

Allparts

http://www.allparts.uk.com/online-shop/guitar-bass-parts/electronics/250k-pots/250k-linear-pot-cts-split-knurled-shaft-p-1548.html

http://www.allparts.uk.com/online-shop/guitar-bass-parts/electronics/500k-pots/500k-linear-pot-cts-split-knurled-shaft-p-1733.html

Thanks!

I started a thread on rewiring my archtop again, and something I'm looking at is the taper of the volume pots. I actually preferred the cheap pots to the pricy Bourns pots. Today I measured the taper on the cheap alpha ones, the bourns, and a CTS for comparison. All are marked as being audio taper, but the alpha pot is pretty much linear. I think I'm going to buy some linear pots to replace the audio ones I have.

you can also custom taper a cts or alpha pot by opening it up and taper scraping the carbon wiper strip - this will increase the overall resistance. experimentation is required. the results can be dramatic - in a good way!

I've heard of that, but do you do it to increase the overall resistance, or to adjust the taper as well?

I've heard of that, but do you do it to increase the overall resistance, or to adjust the taper as well?

can do both.