software

i have an esquire that i slapped togeather. '62 jazzmaster neck with a swamp ash body, reverse slant callaham bridge (lefty bridge with righty saddles) and the pup i wound at ugd. a 11k/6.5k tapped alnico II flat pole tele pup wound with 42 awg plain enamel wire, after putting the string around the coil i had to widen the hole in the bridge to fit the sucker in.

heres the question, i have a three way switch set up with
1- tapped output with tone cap
2- tapped output normal tone control
3- full output normal tone control

ive tried a .015 and now have a .012 for dumping some highs but it still has a little slightly ****ed wah tonality. not all that bad at all but im wondering if there is a way to calculate what frequencies a certain value cap will pass?

Yes there is a formula, i can't think of it at the moment. Wait a while and Artie'll deliver ;-)

Actually, this getting more into Kent S.'s area. The problem is, when you want to calculate the actual rollover point, you now have to take into account the input impedance of the amp, and all that stuff.

The quick amp; dirty formula is f = 1/RC, where:

f = rollover point
R = the pot
C = the cap.

So, assuming a 250k pot and a .022 cap, you'ld have f = 182hz.

But, like I said, thats quot;realquot; rough.
btw - You'ld move the formula around to get cap value:

cap = 1/fR

So, if you wanted a 300hz rollover point:

cap = 1/300*250,000
cap = .013uf

I think.

Artie

hot damn.. that post is vault-worthy lol

i'm writing this one down!

tom

You also need to take into account the inductance of the pickup coils. this affects a parameter called the reactance of the cap.

I was tracing some resources about it on the internet this morning but it's really complicated because most of the stuff deals with audio crossover networks or r/f filter technology. There's little out there on basic guitar electronics.

The formula Artie quoted above is a good rule of thumb. remember that most capacitors come in a series of fixed values and to get a value like .013amp;#181;F you may need to fix up a capacitor network

I think the best way is probably trial and error.

(Off topic: Artie, do you do your artwork and schematics on a Mac? It all looks horribly familiar... )

f = rollover point
R = the pot
C = the cap.

So, assuming a 250k pot and a .022 cap, you'ld have f = 182hz.

But, like I said, thats quot;realquot; rough.
btw - You'ld move the formula around to get cap value:

cap = 1/fR

So, if you wanted a 300hz rollover point:

cap = 1/300*250,000
cap = .013ufOUCH THAT WAS AN INSTANT HEADACHE --LOL!

So artie; in the rollover point, does that mean at that point, the frequencies below that frequency will get shunted as you roll the pot down, or does that mean frequencies above that frequency will be shunted? Like, say the f was = 300Hz... as you lowered the pot, would it reduce the frequencies above or below that number... below right?

above. That's where the pot is no longer effective. The lower value you use, the further up the roll off point goes, and the more intact you leave your original signal.

I like my caps tiny so i don't lose any mid range, just the very highs that pierce a bit too much.


Originally Posted by Quencho092above. That's where the pot is no longer effective. The lower value you use, the further up the roll off point goes, and the more intact you leave your original signal.

I like my caps tiny so i don't lose any mid range, just the very highs that pierce a bit too much.

Depends on the guitar, but I sometimes do the same thing. I rarely want to lose mids, but I'm always looking for ways to tame the highs when they get out of control. I found a nice cap value for a duncan distortion that allowed me to shunt just the highs and leave the mids unmolested. I pulled the cap out of a cheap boom-box that was damaged in a house fire. I'll have to measure it's value to see what it is. This cap allowed me to make a DD sound like an A2 custom when I rolled the tone knob all the way down. This gave me lots of very useful sounds to work with without having to have a whole shelf full of pickups to switch between. Very cool setup, but it lacked the lows I needed on that guitar. I added the Invader to replace the DD and it's been heavenly ever since. The low value cap doesn't really work with the invader. It doesn't have much in that frequency range to shunt anymore. No need to tame highs on an Invader anyway. I might throw that cap in my Hamer Archtop when I get my VVPAF and VVHPAF pickups in...