Cap function?

[teb]

Hey electronics guys....what exactly is the function of the orange caps stuck between the toggle switch and the pots? I happened to notice that my middle toaster (which I wired straight to a volume pot and output jack) seems to sound more crisp and lively than the neck and bridge pickups in the standard five-knob, 360-style configuration with the caps.

[cjj]

Those caps cut some of the low frequencies. It's officially called a "high pass filter", high frequencies go through, low frequencies don't. The frequency where it starts blocking is called the "cutoff" frequency and is determined by the values of the caps and resistors (pot setting), so it's not exactly a set frequency. Also, with this circuit, it's not really a sharp cutoff, it more of a gradual slope, so most stuff just below the cutoff still gets through, but the further below that frequency you go, the more it gets cut.

I could go on and get into the mathematics of it all, but that's probably more than you want to know already...

[teb]

Makes sense, thanks CJ!

[johnallg]

Looking at it from a tone control point-of-view, which these caps and the pots they go to are, they pass the higher frequencies to the pot, which when varied, attenuates more of the highs and the instrument becomes more bassy, as these are not passed by the cap and left for the amp to process. As you turn the pot to a lesser resistance value, more highs are shorted to ground and the pickup sounds bassier.

[chrisdski]

I just restored a 78 4001. The electronics were all mucked up and the bridge pickup was dead. Sergio re-wired the pickup (most excellent job- plug plug) and while rewiring I had .022 orange caps handy for the tone circuit- so I used those. If I understand the previous explanation, the caps are high pass filters (lessens bass) and the tone resistors are low pass filters (increases bass). What effect does using .022 caps vs. .047 caps have - is more or less of the bass frequencies being suppressed with a .022?

[johnallg]

Chris, moving the .047uF tone cap to a .022uF (or even a .01uF) would shunt more mid to low frequencies to ground and make the pickup sound bassier. In the case of the .0047uF cap Todd originally asked about, the one in series with the pickup, changing to a .01uF or even the .022uF you ask about) would allow more bass to pass to the amp and it would almost sound like no cap was there, just a wire.