Tone circuit adjustment advice

[murk]

Hi there good people - my first post here
I'm after advice on my guitar's wiring.. it's an Ibanez single coil strat-a-like from 1980, one tone, one volume.

It's over bright.. (I play through a Mustang modeller amp and  I think that may show up the brightness)

I added a 1.5 meg resistor over the tone pot a few months ago which made a vast improvement.. but I still want to go a bit darker.
Now I tried a 68n capacitor and separately tried a 1 Meg resistor over the tone pot, but both just seemed to muddy it.

I get the feeling I want to push the resonant frequency down and somehow I imagine a drop of 4 tones would be just right!
It's like I need more low mids - but pole pieces aren't adjustable. I've tuned down a semitone too.

Circuit below..
I think this wiring is not the Fender pattern.. could that be causing over brightness?

Any advice gratefully received!

Attachments:

[JohnH]

Hi murk, and welcome to GN2

The sort of change that you are describing can be achieved by putting a small cap between the hot outer and ground lugs on the volume pot. The sort of values that might work are approximately in the range around <1 to 3.3nF, so if you get a few to try, I'd suggest say 0.68, 1, 1.5. 2.2 and 3.3nF ie, every second value of the usual range. If the guitar wiring cant be reached when its strung, some temporary flying leads taken outside the control cavity will let you experiment

cheers
John

[murk]

Many thanks for the advice John - I shall try that this weekend
Just so I understand, am I correct that this is kind of the reverse of a treble bleed type thing?
(i.e. treble bleed feeds treble back into circuit, whereas this dumps treble to ground)

[JohnH]

Jun 13, 2013 17:04:10 GMT -5 murk said:

Many thanks for the advice John - I shall try that this weekend
Just so I understand, am I correct that this is kind of the reverse of a treble bleed type thing?
(i.e. treble bleed feeds treble back into circuit, whereas this dumps treble to ground)

Sort of, but I think a better way to describe it is that it is tuning your circuit. As you noted, there is a resonant peak
, which is in the higher treble range, determined by pickup inductance and varoius capacitances such as that of the cord and other wires, and also the pup windings. Adding capacitance, while inductance stays constant, lowers the resonsnt frequency, above which the response drops quickly.
J

[murk]

ah..
When I added the resistor over the tone pot did that alter the resonant freq ?
I know effective pot value is now 220 k but it sure sounds a lot different than turning the tone pot down

[JohnH]

In theory, that would not change the peak frequency much, but would reduce the height of the peak, thereby reducing high treble content
J

[ashcatlt]

Jun 13, 2013 17:04:10 GMT -5 murk said:

Many thanks for the advice John - I shall try that this weekend
Just so I understand, am I correct that this is kind of the reverse of a treble bleed type thing?
(i.e. treble bleed feeds treble back into circuit, whereas this dumps treble to ground)

Ground is not a destination, but a reference. Get out of that kind of thinking early, and you'll be better off.

Much better to think of this as short-circuiting the high-frequencies. Certain frequencies will find it easier to get back around to the pickup via the capacitor than through whatever you plug it into.

What is actually correct is to think of it as a frequency-dependent voltage divider. The "top resistor" is the series combination of the resistance and inductance of the coil, while the "bottom resistor" is the parallel combination of this capacitor, the cable capacitance, the control pots, and the input of whatever it's plugged into.

[murk]

>>.Ground is not a destination, but a reference. Get out of that kind of thinking early, and you'll be better off.

Good point thanks - I did Physics to A level in UK, but after nearly 40 years the theory drifts away !

[0wnyourtone]

Good advice for lowering the resonant peak.

If you want more LOW mids though, I would try a larger value cap from .01-.033uF in series with a resistor. I'm not sure what a good value for the resistor would be, maybe 60-100K. (You could use a trimpot and dial it in) Basically you would be putting a static tone control across the outer lugs of the volume pot.

If you wanted to do both, lower the resonant peak and blend in a lower mid peak, I imagine you could try a combo of both, although I could see there possibly being negative side-effects to that. I'm not knowledgeable enough to comment there.

[murk]

This could get as bad as GAS.. though I expect that's been noticed already!
Can just see my guitar with ribbon cable hanging out attached to a little veroboard with trimmers and slide switches.

[ozboomer]

Jun 14, 2013 17:30:31 GMT -5 murk said:

This could get as bad as GAS.. though I expect that's been noticed already!
Can just see my guitar with ribbon cable hanging out attached to a little veroboard with trimmers and slide switches.

Actually, it can get a whole lot worse, viz: Toneshaper ...but although you learn a heck of a lot by going through all the mods & combinations, often, the simpler mods that give you some variety in sound and are easy to use are all you really need

YMMV...

[murk]

Well I've gone with the 2.2n - it's a subtle difference when you're trying it out, but when you're playing it's clear it's a lot more smoky.
I probably need to re-balance the value of the resistor over the tone control now!
Thanks - good result.