Treble bleed mod for 1M guitar pot parallel humbuckers

[El Heisenberg]

My volume pots are push/pull 1 med audio log pots. I cab swutch from series to paralell on eash pick-up. Ive been using just plain .001 caps as treble bleed but it was too much for the 1 meg pots, plus the parallel pick ups. Im thinkin of adding the parallel resisyor to the caps, which ive switched to 680pf. 100k or 120k or 150k doesnt sound like itd be enough for a 1 meg pot. What can i do?? I was thinkin a 270k or 300k??

[John Lyons]

Experiment.
You can also put a cap in series with the resistor
to make the bleed (high end) more subtle and more
of a shelved response.
Seymour Duncan and Kinman have some examples on
there sites I believe. Or just search for it here

John

[El Heisenberg]

Yea i knew about that method. I was unsure of how it would make the control respond, and its a pain to open up my guitar and do this because the pots are pc mount, and i need to play for a while before i decide if i like it.

If the resistor in series with the cap would be better for a 1 meg pot, ill try it. But what value resistor? The pick-ups are humboogers. But i usually switch them to parallel.

[stm]

I did some experimentation as well as simulations on this subject, and couldn't find a perfect solution.  Anyway, what seemed to produce the best overall compensation was to place a capacitor (C) in parallel with a resistor (R) between lugs 2 and 3 of the volume pot.  This worked better than a capacitor alone, and better than the capacitor in series with a resistor.

What values for C and R?
Easy.  Start with C equal to your cable's capacitance (in my case my cable measured around 620pF, so I used a 680pF capacitor).  Most balanced response at different volume levels was obtained with R equal to 1/2 the volume pot.  In my case I used 220k because I had a 500k volume pot.  This will give you some values to start with, then see if you are having too much or too little compensation and fine-tune R and/or C accordingly.

Let us know how it goes.

[Johan]

I'm guessing you want 1M pot's so you get maximum treble out of your pickups?....that works as long as you keep the pot at max. the problem, as you discovered, is that when you turn down, you loose a lot of that treble..turning down a 1M log pot to half creates a 900k series resistance for the signal before it hits your input. if you run into a tube amp( or any amp trying to mimic a tube amp), that input might look to the signal as a cap to ground..and that cap value increase with the gain in that first amp stage..look up miller effect..

now, you can battle that two ways. one is to decrease the pot value so the series resistance, when turned down, is not as large..thats why gibson went to 300k volume pots in -73. you loose a little bit of signal at full, but turning down gives a cleaner, sparklier tone...
or you can put a buffer between your guitar and your input...but that only works if the buffer dont have a cap to ground to mimic amplifier input.. ...
j

[El Heisenberg]

Hey

i already tried the series method on the bridge pick up. I used a 120k with a 471p cap. Bridge i used 680p cap and no resistor. I have 1 meg pots so i guess i will try 470k Although i remember trying 330k and losing the low end. Or just losing too much volume but keeping more treble.
what i was wanting to fix was having too much treble. With my 1meg pots,id turn the control down slightly and lose too much volume but have a harsh amount of treble. What i also did was reduce the pot values to 680k by putting 2M2 resistors across the pots. Im not sure if this is working right coz i could only get measurmets of 360 at full. My pots are wired different so i can turn down both pick ups while both are selected. The signal goes into lug two and out of lug three.

I also have a 1M pot before the output with a .0022 cap across it as a bass cut. This complicates things too.

[El Heisenberg]

 should mention its a weird guitar. A ric 330 copy made by orlando who i heard had made gibson copies. I got it 2nd hand from Paul Gilbirts stash that hes selling at this shop. It was already rewired so that the blend was the master volume and the four other pots were bypassed. Just volume and pu selector.  The pick ups came with dimarzio color wiring and i wired them to switch between parallel and series to take care of the darkness of it.

[Paul Marossy]

should mention its a weird guitar. A ric 330 copy made by orlando who i heard had made gibson copies. I got it 2nd hand from Paul Gilbirts stash that hes selling at this shop. It was already rewired so that the blend was the master volume and the four other pots were bypassed. Just volume and pu selector.  The pick ups came with dimarzio color wiring and i wired them to switch between parallel and series to take care of the darkness of it.

Hmm... would the seller be Cowtown Guitars?

[El Heisenberg]

Yea