Low Cut sw mod... what did I do wrong?

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Harmoncj
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Low Cut sw mod... what did I do wrong?

Post by Harmoncj » Sat Nov 14, 2020 6:22 pm

Trying to make the rhythm sw into a hi pass filter , and its so irritatingly close to working.

what I started with. (stock jazzmaster wiring)
Image

what I just did...
Image
PROBLEM. Almost does what I wanted. the switch works right but when you use the knob to low cut,, you also get a bit of hi cut, so its more of a cocked wah sound. I remember planning it on breadboard and not finding a lot of good cap values settled on 471 which is oddly small

I think the problem is that the low cut filter needs to come before the volume knob to work effectively but I can't demo this on breadboard obviously so I wanted a second opinion/ I think this is the solution:
Image
convoluted as it may seem. is there any way to predict what cap value would be good in this situation? I might go with the trusty jaguar choke switch ~302 and hope for the best

thanks for any help!!

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jorri
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Re: Low Cut sw mod... what did I do wrong?

Post by jorri » Sat Nov 14, 2020 6:47 pm

Is it causing interaction with the lower tone cap? You can also wire a high cut with resistor on hot and only cap to ground, so maybe, especially if the lower tone is rolled down. Also If you want highs why have the added tone rolloff a tone pot with do on full?

It could also just be a matter of chosing a better cap value...

What could be more convenient is somehow bypassing the tone control. But i have only done that with a non-variable, since those use spst switch, i used the other side of a dpdt to disonnect the tone control....

But yes i have idea if you wish to do this the same way a regular strangle is wired, i think you can only use one side of the switch to bypass it. You wire volume and jack to e.g. pin 1 and 2 (centre and another) then wire the strangle pot to the SAME pins, so when engaged it shorts the strangle, when not it passes through it.
Then you other side to connect whichever passage of the tone circuit is convenient to two pins in a similar manner so it connects the circuit when engaged.
***If you find a jag wiring diagram with dpdt it may show this.

I do not know if before or after volume would affect it, i wouldnt have though so??

If you can try it with clips sans switch that may help circuit designing it.

Harmoncj
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Re: Low Cut sw mod... what did I do wrong?

Post by Harmoncj » Sun Nov 15, 2020 3:24 pm

thanks for the help jorri! but it hit me the next morning, just use a drop down resistor at the end to simulate volume knob after the lo cut filter. I do not know technically speaking why exactly you need this... impedance something but I just know it works and sounds more correct this way. and I am getting desired results with cap values closer to the range that youd see as a jaguar choke switch.

THIS IS THE CORRECT SCHEMATIC FOR A LOW CUT MOD:
Image

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jorri
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Re: Low Cut sw mod... what did I do wrong?

Post by jorri » Mon Nov 16, 2020 4:38 am

I don't fully understand but it gives the cut freqs somewhere to drain and separation from amp. In many circuits a pulldown resistor is the first and last thing, or it just sees the RC filter impedance and interacts with it?

Harmoncj
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Re: Low Cut sw mod... what did I do wrong?

Post by Harmoncj » Mon Nov 16, 2020 5:33 am

I'm not completely sure but it has to be related to those 2 reasons you described, I just know it was creating a mids effect without that extra resistor, might have even solved it by simply running into a buffered pedal but I wanted to fix it right for all situations.

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