Baffling tone sweep problem

[ChrisV13]

Hi guys, new member and first time posting so thanks in advance for your help.
I'm trying to split the coils on my 2hb guitar so the setup will be 2 vol and 2 tones with push pulls. Ive followed the exact schematic from Seymour Duncan but have a weird problem with both tones that they sweep their full amount bass to treble in the first 15-20% of rotation. They're both linear B500k pots and when testing with a multimeter the sweep works fine, gradually from 0-500k ohms. Ive tried both 33 and 47 caps.
Any ideas? I'm stumped!

 

[DrNewcenstein]

Re: Baffling tone sweep problem

I use A250K tone pots and everything's hunky dory.

 

[ChrisV13]

Re: Baffling tone sweep problem

Er, thanks but that doesn't really help me! I want linear pots, just don't understand what's going on electronically.

I use A250K tone pots and everything's hunky dory.

 

[beaubrummels]

Re: Baffling tone sweep problem

It's because you are using linear taper pots. Try audio taper. Use alligator clip wires just to test it if you don't want to solder it all.

 

[ChrisV13]

Re: Baffling tone sweep problem

Audio tapers are a logarithmic scale, linear are a "straight line" progression through the sweep of the pot which is what i want for the tone pots. What i'm getting though is a very fast taper from min to max within about 20% of the pot sweep, not a gradual sweep per the multimeter test i've done. Switching to audio pots won't explain what is going on here, i'm looking to see if anyone can help explain this, not just suggest audio pots. Thanks!

 

[frankfalbo]

Re: Baffling tone sweep problem

Er, thanks but that doesn't really help me! I want linear pots, just don't understand what's going on electronically.

Audio tapers are a logarithmic scale, linear are a "straight line" progression through the sweep of the pot which is what i want for the tone pots. What i'm getting though is a very fast taper from min to max within about 20% of the pot sweep, not a gradual sweep per the multimeter test i've done. Switching to audio pots won't explain what is going on here, i'm looking to see if anyone can help explain this, not just suggest audio pots. Thanks!

You're not listening. Your linear taper pots are doing their job, but the result on the resistor/capacitor network is that it doesn't sound smooth and even. Exactly the same reason linear pots don't sound smooth and even when used for volume controls on guitars.

The people suggesting you try audio taper pots are right. Linear taper pots, in my experience, will do EXACTLY what you're complaining about.

 

[ChrisV13]

Re: Baffling tone sweep problem

Sorry wasn't trying to be dismissive, but i must be missing something - the multimeter moves gradually through the whole sweep from 0 to 500, but my ear says its only the first 20% of the sweep that moves the tone from all bass to all treble. Ive had linear tone pots before and it hasnt sounded like this, which is why i've posted this thread in the first place.

 

[beaubrummels]

Re: Baffling tone sweep problem

Try watching this guy's explanation and see if it has your answer.

 

[Archer250]

Re: Baffling tone sweep problem

Your ear hear things logarithmically. Go ahead and stick to the multimeter if you want, but it's not gonna get what you need.

 

[GilmourD]

Re: Baffling tone sweep problem

Sorry wasn't trying to be dismissive, but i must be missing something - the multimeter moves gradually through the whole sweep from 0 to 500, but my ear says its only the first 20% of the sweep that moves the tone from all bass to all treble. Ive had linear tone pots before and it hasnt sounded like this, which is why i've posted this thread in the first place.

Your ear hear things logarithmically. Go ahead and stick to the multimeter if you want, but it's not gonna get what you need.

I'm quoting Archer250 just to get the point across.

What the ear hears and what the meter says are completely different things.

If you really want your head to explode, read up on Fletcher-Munson curves.

 

[ChrisV13]

Re: Baffling tone sweep problem

Wow, thank you so much beaubrummels, couldnt have asked for a more comprehensive answer than that video clip of the guy from Ann Arbor Guitars. Explained everything and really clearly - time to hit ebay for some 22 caps and an audio push pull. Thanks again, if i could give more than +1 i would. Thanks everyone else for chipping in and sticking with me through my insistence!