Special FM Tone Caps

[nervous]

My 1993 had a .01 tone cap:

And my 1996 has a .022 tone cap:

What's the difference and how does it affect the tone control function?

Thanks.

[BubbaVO]

Did you search the board? This has come up somewhat regularly.

But the basic rule is: : the higher the capacitance, the darker the tone.

Here's a pretty good article that I will occassionally re-read when I'm thinking about trying something different:

http://www.premierguitar.com/Magazine/Issu...Capacitors.aspx

http://www.premierguitar.com/Magazine/Issu...rs_Part_II.aspx

[nervous]

I did check teh archives but couldn't find a simple explaination of what they do. I did find this to add:

As far as cap values go, the higher the value, the darker the tone at any given point in the pot rotation. 0.1uf being darkest, with 0.022uf being brightest (smaller values like 0.015uf or 0.01uf are used to brighten up exceptionally dark sounding guitars, and add extra bite). Humbuckers have less highs because of phase cancellation and use a brighter cap like 0.022uf or 0.033uf. Single coils need more highs removed to sound good, and use anywhere from 0.022uf in Modern SSH Strats, and 0.047uf (0.05uf) to 0.1uf in vintage Strats and Teles. Gibson P90s typically use 0.033uf, and will really scream with 0.015uf or 0.01uf Paper In Oil caps.

So, assuming that uf is the same value as mf (both micro-farads right) I guess that means the .22 I have in the '96 will be a little less bright than the .01 in my '93. Then again, from other things that I have read the differences are imperceptible anyway. Just a curiousity, that's all.

[Uncle Thor's Hamer]

Good topic, I've been thinking about tinkering with my tone cap.

The tone pot is resistance, and the capacitor is capacitance. The two combined define a 3db point. 1/(2*pi*R*C) gives a frequency which is considered the knee of the curve. Above that point the high frequencies are cut more, below that frequency the signal is considered unaffected.

It is a "low pass filter", letting through low frequencies. As you rotate the tone pot you will change the R in that equation, changing the knee of the curve for the same value capacitor.

If you change the capacitor value, there is a corresponding change in the starting frequency with the tone pot at full treble. Go to a smaller cap and you get more high frequencies with the tone pot at full treble. Go to a larger cap and the max treble is a lower frequency to begin with.

Say you have a small cap with a full treble cutoff of 6khz. This means that all frequencies below 6khz will pass through to your amp, and those above will be blocked. If you swap out the cap for one with twice the value, the starting full treble cutoff frequency will now be 3khz. The guitar will sound darker at full treble.

The situation is a lot more complicated because the circuit is not ideal. The pickups have resistance and inductance due to the coils. There is distributed capacitance is the wiring. The volume pot can affect the resistance as you turn it down (though Hamer uses a circuit that minimizes the interaction). Capacitors themselves are not perfect and have complex interactions internally. Finally, the wire to your amp and the amp itself can influence the circuit. All that to say that you can't really just do a quick math calculation to find the right cap value, you need to experiment.

A quick addition. The change in capacitor only affects the full treble settings. If you roll the tone control off until you like the sound, changing the tone cap will only affect how far you turn the tone knob.

For example, the Newport gets a real mellow jazz tone at about 4 on the tone knob. Changing the cap will mean using maybe 2, or maybe 7 on the tone knob to get that same sound.

If you run at 10 on the tone knob then the change in cap will make it darker or brighter. Otherwise there is no reason to change out the cap.