volume pot taper tweak?

[daz]

I have often used a resistor across a pot to change value, but is it possible to change the taper by going from wiper to input lug with a resistor? Heres the problem. I have a P90 LP with 500k pots which i verified are audio taper. But the taper is just too radical. I use overdiven tones all the time and get my cleans by rolling the volume pot down. But It really doesn't clean up much till it's on 2-3. I would like a taper that would get as clean as it is now on 2-3 when on 5. Anyone know if i can solder a resistor across the input lug and wiper to make that happen, and if so what value? I can experiment but i'd like to have an idea of whether it will do what i want and what approximate value to use. Thanks.

[Enzo]

RG Keen has a good article about this on his GEOFEX.COM web page. Under tech tips: The Secret Life of Pots.

Hopefully I have the link correct here:
http://geofex.com/Article_Folders/po...s/potscret.htm

[Helmholtz]

I have often used a resistor across a pot to change value, but is it possible to change the taper by going from wiper to input lug with a resistor? Heres the problem. I have a P90 LP with 500k pots which i verified are audio taper. But the taper is just too radical. I use overdiven tones all the time and get my cleans by rolling the volume pot down. But It really doesn't clean up much till it's on 2-3. I would like a taper that would get as clean as it is now on 2-3 when on 5. Anyone know if i can solder a resistor across the input lug and wiper to make that happen, and if so what value? I can experiment but i'd like to have an idea of whether it will do what i want and what approximate value to use. Thanks.

I understand you need more attenuation at lower settings. A resistor between input and output won't help as it will pass more signal. I think you need audio taper pots with 10% output at 50% travel. Maybe Chuck could recommend some type?

[daz]

I got it. I found something in a google search that said to use a value of 20% of the pot value from wiper to ground and that worked perfectly. The keen site....i've seen it but my math skills are comical at best, so looking at those formulas to me is like trying to read a language i never even heard of.

[Helmholtz]

I got it. I found something in a google search that said to use a value of 20% of the pot value from wiper to ground and that worked perfectly. .

THat's not a good solution either as it will load down your PU signal noticeably at full volume.

[daz]

THat's not a good solution either as it will load down your PU signal noticeably at full volume.

I think u r right, as the tone on 10 sounds sorta nasally. I'll try wiper to input.

[daz]

I think u r right, as the tone on 10 sounds sorta nasally. I'll try wiper to input.

Eh, no go there either. (wiper to input) Thinking about it that just lowers the resistance between in and out so it did exactly what i would have expected if i had thought about it b4 i tried. That being it cleaned up even LESS as i rolled it down. Oh well, was worth a try. Anyone know of 500k pots with a taper that will cut gain quicker in the rotation?

[Helmholtz]

I think u r right, as the tone on 10 sounds sorta nasally. I'll try wiper to input.

See post #3. Adding an external resistor cannot give the same results as a different value or different taper pot.

[nevetslab]

Audio taper pots, at 50% rotation are 10% of the resistance, while Linear is 50% of the total resistance. Allen Bradley Type J pots had a DB taper, which yielded more like 2-3% of total resistance at 50% rotation. Fender makes use of 30% Audio taper pots in their tone control circuits of tube amps. I think some of those controls are 250k. I'd have to look. I looked thru my data sheets of different pot mfgrs, and most of them only offer Linear, Audio (10%) and reverse Audio tapers.

I've attached the data sheet on the Allen Bradley Type J, which on page 3 of 17, it shows all of the pot tapers they offered. You could pencil in the approximation of the 30% Audio taper that Fender has used to get an idea.

Allen Bradley Type J Pots.pdf

[Helmholtz]

As nevet wrote, problem is that not all audio taper pots measure 10% resistance at 50%. Some are up to 30%. I wonder what is in that guitar.

[Helmholtz]

Seems the CTS series 450G with A or even C taper should be appropriate: https://www.ctscorp.com/wp-content/uploads/450G.pdf

[pdf64]

The 15% dead zone at the start of CTS audio tapers is somewhat off putting.

[mozz]

Are you sure the pot is grounded and it's a real audio taper? Post pictures, model,type.

[daz]

Yes, they are audio and wired correctly. Been modding guitars since the 70s so trust me on that. And the one i checked was about 450k and at 50% rotation the measurements to wiper from the ground and input lugs (after removing all circuitry) is approximately 375k/75.k

I suspect the P90s are the reason i never had this issue b4 because i have always been 99% fender and have only owned 2 P90 guitars. I have used hundreds of pots and never ran into taper like this when using them in fenders.

[mozz]

It can't be higher, 475k if the pot is only 450k? They could just be worn out.