Help with Tone/Filters

[CPK]

Hi guys,

I've recently upgraded the pickup on my P Bass to an EMG GZR, which I absolutely love. It sounds great with the tone wide open. One thing I really miss though, is being able to roll off a lot of those highs when I need to. For this reason I'd like to mess around with the tone circuit.

I've dabbled a little in electronics before, so understand it's an RC filter, but still can't work out exactly what I'd have to do to give that filter more range. I'd like to keep all the highs intact with the pot wide open, but have a much lower cutoff with it all the way down. Does this make sense?

Do I need to change the pot, the cap, or both?

Cheers

 

Edit:

In order for me to better understand how these work, could anybody tell me, roughly, what value a 250k pot should read when it's all the way open? Should it be very close to zero? In other words, the tone circuit is entirely bypassed?

Edited January 12, 2020 by CPK

[Stub Mandrel]

Try wiring the capacitor across the wiper and bottom contact of the pot.

This removes it completely at one end.

For the most you can get out of a passive tone control, fit a Fender TBX kit.

https://www.rattleanddrum.com/fender-tbx-tone-pot-genuine-fender-parts.html?gclid=CjwKCAiApOvwBRBUEiwAcZGdGHLjeY9sPwpjpAQVu3FylPyQPphSh4jpT25CQTk9do0mpRJWf82ttxoC-2sQAvD_BwE

 

[itu]

If the pot is very big, like they tend to be, the lowest setting can be from few ohms to few hundred. The accuracy of those low end carbon track pots is not fascinating.

As long as you have any passive pots in the circuitry, they act as filters. They cut the highest end of the frequency spectrum. If you bypass any pots in the circuitry (remember that we discuss about a passive, so high impedance circuit), the response will widen.

The reason to use big pots is to reduce the effect. A common hi-Z bass has two to four pots in parallel, so the impedance is not 500 k or 250 k but something much lower.

Another thing is if your system is lo-Z and the adjustments are made by active circuitry. Then the pots do not affect the response.

[ikay]

A higher value cap will cut more highs. Eg. a 0.1uf cap will give a darker sound than a 0.47Uf cap with the tone turned down. What's in your bass at the moment? If you also want a brighter sound with the tone fully open you could use a no-load tone pot which effectively removes the pot from the circuit when fully open.