What cap value....

[Chuck H]

Well now that's a thought. Maybe daz's guitar would benefit from a bass control. Not a complicated circuit and would allow for adjustment without putting a cap in series with the pickup so stock sounds could still be accessed. I'm all about push/pull pots of guitars whenever it can help.

EDIT: It occurs to me that with a bass cut control on a push pull switch the tone control could simultaneaously be disengaged. This would add some bite to the intended effect and help to define notes. ie: reduce mud.?.

[35L6]

Does a series cap affect the resonant peak ?

[Helmholtz]

Does a series cap affect the resonant peak ?

Good question.
I think the resonance will be pushed to a slightly higher frequency, maybe by 5% depending on details.
But that's best examined by simulation. Chuck?

[Chuck H]

Good question.
I think the resonance will be pushed to a slightly higher frequency, maybe by 5% depending on details.
But that's best examined by simulation. Chuck?

On it. Be right back...

EDIT: Ok. So, interestingly with or without a 6.8n cap in series with the pickup the "peak" remains the same in the simulation. 2.94kHz for my PAF model using a 20 foot cable-ish. But if I instead read the center of the "crown" formation itself then adding the cap moves it from about 2.86kHz to 3kHz. Not a big deal but I think it's interesting that the true highest frequency didn't change even though the overall resonant peak formation shifted.

[35L6]

That is interesting . Pictures ?

[Chuck H]

Including the graphic. Only when overlaying the two plots (I have to do this manually with MSPaint) did I notice that there's a roughly 1dB drop in overall amplitude along with the frequency shift.

[Helmholtz]

Including the graphic.

Thanks Chuck.
Your sim result confirms my simple theory.
The additional cap acts in series with the cable capacitance and lowers the total capacitive load of the PU, thus increasing the resonant frequency.
E.g. if the cap is 10 times larger than the cable capacitance, total capacitive load is decreased by roughly 10%, which results in a 5% higher resonant frequency.

The 1dB overall drop is caused by capacitive voltage divider effect.

[Mick Bailey]

I've modified a few Jazzmasters to include a bass cut & regular treble control in the 'rhythm' position. This has worked exceptionally well - especially with the bass cut. This was a 0.0022uf cap in parallel with a C1M pot in series with the signal and before the volume pot. A similar arrangement with an appropriate cap could be mounted inside the guitar with a trim pot and using a regular 1M trimmer to give an adjustable cut.

[Dave H]

Including the graphic. Only when overlaying the two plots (I have to do this manually with MSPaint) did I notice that there's a roughly 1dB drop in overall amplitude along with the frequency shift.

You don't have to use Paint to overlay the plots, LT Spice will do it for you. For example, right click on the series cap and set its value to {1n*a} then add the spice directive .step param a list 6.8 10000 to the schematic. The spice directive is under the 'Edit' tab.

[pdf64]

Some vintage Rickenbackers have a bass cut cap, but on their bridge pickup, presumably to make it super trebly https://www.rickenbacker.com/wp-cont...4/01/19502.pdf

[daz]

OK, a lot of this goes over my head so i'm not sure, but i think some are thinking i'm asking about a tone control cap. But no, i talking a cap in series with the pickup's hot wire. Like a bass control but without being adjustable, but dropping frequencies below around 100Hz. Anyways, i tried it but wasn't particularly happy with the results. Might work better with a bigger cap value and pot as a bass control, but i wanted it to only affect the neck so thats out because i have my LP wired like a fender....pickups to the 3 way, common to the single volume control. In any case i experimented a lot and it doesn't work as well as i remember from past experiences.

[Mick Bailey]

I was thinking along the lines of fitting an adjustable cap/pot filter in series with the pickup inside the guitar so you could trim it where it sounds best.

Another idea is to use two caps and a trimpot to get a broader range. I did this on a LP for a customer and he really liked it. So much so that he only used the neck pickup afterwards. I think that was a 1n and 22n cap. I can't recall the trimmer value but think it was 100k. Connect the smaller cap in series with the pickup and parallel the larger cap + pot.

[Chuck H]

OK, a lot of this goes over my head so i'm not sure, but i think some are thinking i'm asking about a tone control cap. But no, i talking a cap in series with the pickup's hot wire. Like a bass control but without being adjustable, but dropping frequencies below around 100Hz. Anyways, i tried it but wasn't particularly happy with the results. Might work better with a bigger cap value and pot as a bass control, but i wanted it to only affect the neck so thats out because i have my LP wired like a fender....pickups to the 3 way, common to the single volume control. In any case i experimented a lot and it doesn't work as well as i remember from past experiences.

What capacitor value did you use?

[Mark Hammer]

I was thinking along the lines of fitting an adjustable cap/pot filter in series with the pickup inside the guitar so you could trim it where it sounds best.

Another idea is to use two caps and a trimpot to get a broader range. I did this on a LP for a customer and he really liked it. So much so that he only used the neck pickup afterwards. I think that was a 1n and 22n cap. I can't recall the trimmer value but think it was 100k. Connect the smaller cap in series with the pickup and parallel the larger cap + pot.

Took the thought right out of my head. Both Reverend and G&L guitars have used a "contour" control that provides a variable resistance and parallel capacitor in series with the pickup on the way to the volume pot. Full bandwidth signal passes through the pot, and bass-reduced (highpass) signal passes through the cap. Adjusting the pot that provides the variable resistance adjusts the relative balance of bass-trimmed and full-bandwidth signal. That said, I suspect the OP wants something with a steeper slope. I'm thinking that what he really needs is not something on the guitar itself, but rather a proper 2-pole, or even 3 or 4-pole, highpass filter in a box. The "mud" is going to come from how all that deeper bass impacts on pedals, the amp and speaker/s Yes, it is ideally eradicated in the guitar itself, but first-thing-after-the-guitar ain't so bad, either. It also means one wouldn't be reducing the guitar's output via passive loss. A proper active highpass filter could do the job well, without any signal loss apart from what one filtered out.