Choosing pot values, Vol-blend-tone

brock29609 · #1 11-15-2006, 07:42 AM

If I want to convert a P/J pickup configuration from vol-vol-tone to vol-blend-tone without changing the sound, should I not switch to 500K pots from 250? A blend pot will put an extra load on the circuit, correct? Should I use a 500K blend pot with 250K vol and tone pots? Can you mix and match the pot values?

Again, the goal is to keep the tone the same as it is now, while changing the controls.

luknfur · #2 11-16-2006, 05:31 AM

Quote:

Originally Posted by brock29609

If I want to convert a P/J pickup configuration from vol-vol-tone to vol-blend-tone without changing the sound, should I not switch to 500K pots from 250? A blend pot will put an extra load on the circuit, correct? Should I use a 500K blend pot with 250K vol and tone pots? Can you mix and match the pot values?

Again, the goal is to keep the tone the same as it is now, while changing the controls.

FWIW:

I personally have never been able to tell any significant difference between a 250 and 500K pot - but some guys can.

Buy one or both blends, drop one in and see what you think. Doesn't hurt to have an extra blend around and you're probably equally likely to find you like it better, no change, or worse.

Whassap · #3 11-16-2006, 12:49 PM

What kind of store can you find pots at? I went to a local Hardware - Electronics store and didn't have any luck. I saw an article a while back about making my own piezo pickup, thought it would be sweet to set up in into my acoustic guitar with a volume knob. I have some soldering/wiring skills, I've never gotten into guitar/bass electronics but I really want too.

luknfur · #4 11-16-2006, 01:37 PM

Quote:

Originally Posted by Whassap

What kind of store can you find pots at? I went to a local Hardware - Electronics store and didn't have any luck. I saw an article a while back about making my own piezo pickup, thought it would be sweet to set up in into my acoustic guitar with a volume knob. I have some soldering/wiring skills, I've never gotten into guitar/bass electronics but I really want too.

Highly unlikely you'll find what you're looking for at GC let alone otherwise. Go online to Stewmac.com, guitarelectronics.com, allparts.com, etc.

This would be a good idea too:

DIMENTO'S BASIC TROUBLE-SHOOTING GUIDE

knarleybass · #5 11-16-2006, 01:43 PM

I like the blend pot as well, but it seem like on some of by basses that when it's in the middle you get a good blend of both pickups, but when I turn it just slightly to one or ther other pickup the picups totally dominates the other... Is this because I have the wrong value?

luknfur · #6 11-17-2006, 12:41 AM

Quote:

Originally Posted by knarleybass

I like the blend pot as well, but it seem like on some of by basses that when it's in the middle you get a good blend of both pickups, but when I turn it just slightly to one or ther other pickup the picups totally dominates the other... Is this because I have the wrong value?

FWIW:

Long time since I've used onboard electronics on a regular basis and seems like I got that on occassion. Too long ago to really remember but my guess is it wouldn't be in the pot but how it's wired. It should be smooth off the detent, equivalent to having two volumes with both maxed and backing off one. There will definitely be a variation in volume across the entire spectrum in a standard blend, just like with extremes with two volumes.

The Dave · #7 11-17-2006, 10:14 AM

I changed my Jazz to Vol/Blend using a 500k blend pot and I can tell some difference in the sound. There's more openness and clarity, which is what I was looking for. I'm using DiMarzio Model Js and they're a little too much for the 250k pots. Anyhow, If you want the same sound, I'd certainly recommend a 250k blend. Get some extra wire and a solder remover too. You can use one of the sites already referenced or www.basspartsonline.com I was able to find a blend pot at a local shop but, depending on where you live, that might not be an option. Just allow plenty of time and go slow. I also HIGHLY recommend testing BEFORE you solder everything in place. I did this (more out of fear than wisdom) and found that my wiring diagram was off. So, I kept moving wires around until everything worked right. THEN I started soldering.

brock29609 · #8 11-17-2006, 01:17 PM

Quote:

Originally Posted by knarleybass

I like the blend pot as well, but it seem like on some of by basses that when it's in the middle you get a good blend of both pickups, but when I turn it just slightly to one or ther other pickup the picups totally dominates the other... Is this because I have the wrong value?

Your blend pot is probably linear instead of audio. Audio pots give a more subtle adjustment when you first turn it. With audio pots, you'll see <50% roll off at half a turn. Linear pots make exactly a 50% roll off at the half turn point.

I figure that changing the master vol and blend pot to 500K equals the same resistance as one 250K vol pot. I'm going 500-500-250 with my vol-blend-tone pots. That should match the stock resistance. Each pickup will have to go through two 500K pots instead of one 250K vol pot (excluding the tone pot). Same resistance either way.

luknfur · #9 11-18-2006, 01:06 AM

Quote:

Originally Posted by brock29609

Your blend pot is probably linear instead of audio. Audio pots give a more subtle adjustment when you first turn it. With audio pots, you'll see <50% roll off at half a turn. Linear pots make exactly a 50% roll off at the half turn point.

I figure that changing the master vol and blend pot to 500K equals the same resistance as one 250K vol pot. I'm going 500-500-250 with my vol-blend-tone pots. That should match the stock resistance. Each pickup will have to go through two 500K pots instead of one 250K vol pot (excluding the tone pot). Same resistance either way.

Interesting thought. Never thought about it or messed with it but they make both log and linear taper blends. Why I don’t know. My guess is the taper aspect of the blend wouldn’t matter otherwise all blends would be audio. Even though the blend is substituting for a second volume it’s not the same function. Graduated audio signal for the blend should be taken care of by the accompanying audio volume, but I could see it going either way.

Most pots have designations, an audio will have audio, A, or log stamped in it. Probably T, Lin, or B for linear but not sure about that.