5 position tone switch cap values

[jaystainbrook]

Hi everybody. I want to put together a 5-position tone switch for my bass (Westone Quantum) and I was wondering if anybody had ideas about what the cap values would be ideally. Right now it's a .047 uF which to me sounds pretty middle of the road. Ideas?

[GlennW]

I've made a few and like .1, .069 (.022 and .047 in parallel), .047, .033, .022. I rarely used the .022, but had to fill a spot. You could use no cap for a position as well.

I'd suggest you get a bunch and see which ones you like before you start soldering.
Run a couple of wires 6" or so from the tone pot (if you're using one) and let them exit between the pickguard and body; that way you can swap caps will minimal effort and get an idea of how they sound.

[jaystainbrook]

I got one together with those values. I'm not using a tone pot, instead I put a 500k resistor in it's place to simulate keeping it closed. However, the effect was really subtle, which I guess makes sense since the resistor is limiting the effect of the caps.
So I took it out, and while the effect was more audible it wasn't the sound I was looking for. I was under the impression that there was a resonance peak in the freq response that was higher with the tone control closed. I want to get the sound of different caps without rolling off too much of the highs. Am I doing something wrong, or did I already get that and it's supposed to be really subtle?

[GlennW]

Originally Posted by jaystainbrook

I want to get the sound of different caps without rolling off too much of the highs.

Rolling off the highs is what caps do. The bigger the value, the more highs get cut.

IME the tone pot chokes it very noticeably. They seem to have more presence without the pot (I don't use volume pots either, so that may be a factor). What I'm getting at is a .1uF cap with no pot will sound brighter than the same cap with a pot turned on 0.

Lately I've been using only one or two cap selections (or three with a on/on/on switch) because while in theory it seems cool to have a lot of options, in reality you don't need all that because you can tweak the amp to compensate for small changes in cap values.

If I were you I'd leave out the resistor and/or pot and and try to find a couple of cap values you like instead of trying to fill the switch.

I wouldn't call hte differences subtle; a .1 and a .022 aren't similar at all. What kind of caps are you using? I'll find Mouser's OD page and add it.

http://www.mouser.com/catalog/629/666.pdf

The top right section contains the ones I use. A few of some of the first four values should give you enough to find something you like since you can add them in parallel to make "in between" values.

[jaystainbrook]

I pulled the switch, the resistor and everything else that I mucked up and did what you suggested in the first place - run a couple of wires out of the control cavity and try out different caps. Now I can hear an audible difference which makes me think I must have had something soldered up wrong.

I read online here : http://www.sugardas.lt/~igoramps/article57.htm
As well as in Kuhnel's great book on preamp design: http://www.pentodepress.com/
That the tone cap does more than just roll off the highs. It also boosts the "mids" by interacting with the pickup's inductance. The advantage of a switch instead of the typical tone pot is that you can adjust where the highs roll off without losing that extra boost. That's what I was trying to say earlier. They explain it alot better than I do.

All the theory in the world doesn't help, of course, if I can't solder my way out of a paper bag.