WAH on Telecaster

[StromTele]

Looking at constructing a fixed (cocked wah) tone control with an passive RLC circuit, (employing the obvious inductor).

 

[Lightium]

Very little people here speak musician jargon. Be specific and/or post a link.

 

[StromTele]

500K logarithmic push/pull potentiometer with an attached RLC circuit - resistor/inductor/capacitor.

 

[Lightium]

What problem did you have, schematic/part values?

https://diagramweb.net/img/wah-pedal-wiring-diagram-3.gif

 

[StromTele]

Schematic primarily. I think/hope I can calculate values for a mid high range in Hertz

 

[StromTele]

This is not for a Pedal. This is passive.

 

[Lightium]

So, it's passive and for audio tone control?

 

[StromTele]

Correct. No pedal, no battery.

 

[Lightium]

I imagine if you put your inductor across the output of a regular two knob tone control, that's be a start.

 

[StromTele]

Push /pull logarithmic tone pot

 

[rjenkinsgb]

Mod: Bridge tone control, with Eldred mod 'cocked wah' sound

Hi all! This is a mod that I've not yet seen on the forums, though it's based on a mod from guitarnuts.com. The link is : http://www.guitarnuts.com/wiring/simplebtone.php, and an Andrew Rodgers is credited with it. Guitarnuts says: The tone controls work completely normally in positions one...

www.tdpri.com

Another version:

 

[StromTele]

Thanks ! Not looking for the Eldred or Arlo mods. Am familiar with those. Wish to have a passive RLC configuration

 

[rjenkinsgb]

OK, then a parallel resonant LC circuit tuned to the wanted frequency, connected across either the pickup to volume point or the final output of the guitar, via the push-pull pot switch.
(What guitar would you be adding it to? Tele in your name is probably bit of a giveaway? That's one type I do not have..)

A section of a pot in series with the switch could adjust the depth of the cutoff either side of the peak.

What frequency (or string/fret) would you want it centred on?

 

[rjenkinsgb]

For info, an LT700 audio transformer is nominally 550mH on the high impedance winding. They are 16x16x20mm, readily available and cheap. (Ignore the other winding).

With a 0.47uF in parallel, that gives a resonant frequency of ~313Hz, very close to an open high E string at around 330 Hz.

The frequency changes with the square of the capacitance change; using 1uF makes it around 215Hz, or 0.1uF gives 679Hz.

(Assuming the inductance and capacitance are in tolerance).

 

[JimB]

The frequency changes with the square of the capacitance change;

I think that you mean square root of the capacitance change.
Looks like a typo, your numbers are OK.

JimB

(Or, should I say the reciprocal of the square root of the capacitance change.)

 

[StromTele]

Yes !!! For a tele, and was looking at upper mid frequency range, which I'm guessing around 800-900 Hz. Wished to put it on the tone pot as an option.

 

[rjenkinsgb]

OK, A 68nF would give around 823Hz, or 56nF 907Hz

Because of the possible component tolerances, I'd probably try a 47nF then add 4.7 and/or 10nF caps to bring it down to the sound you like.

You could possibly use the changeover switch to swap from the fixed tone cap to the tuned circuit? It would then become depth rather than tone.

 

[StromTele]

Excellent ! Thanks. Could you sketch out a couple workable RLC schematics for the push-pull?
I think the down position of the pot would just be something like 0.022 as a base brighter sound. Thanks, Marc