How does a Treble Bleed circuit work? April 18 2012
Electricity only does one thing, it searches for ground. OK, let's hold this thought for a minute.
First you need to know how the volume pot is wired. It has three pins on it, the middle pin (wiper) goes to the output jack, one end (counter clockwise) goes to ground and the other end (clockwise) receives the pickup's signal. When you turn the pot, the wiper gets closer to one of the end pins. When it's turned fully CCW, the signal is shorting to the volume pot ground and you get no sound. But when it's turned fully clockwise, the signal bypasses the volume pot ground and goes to the jack to find it's ground. Now with modern wiring your tone control signal passes through the volume pot which is tied to ground on one end so remember electricity searches for ground.
By turning your volume control down, you're allowing some of the signal to "bleed" into it's ground pin. When you do this, the frequencies that leave first are the higher ones (treble), which makes the tone seem muddy and thick or without the "edge" on it.
A way to avoid this is by using a "treble bleed" circuit. It's called this because it prevents the treble (high) frequencies from bleeding off to ground. It accomplishes this by allowing these higher frequencies to sidestep the volume control rather than go through it and get it's ground from the jack. This is pretty much what the Vintage 50's wiring does (to be discussed later). This circuit can be just a capacitor or a resistor & capacitor combo in series or parallel. It all depends on what frequencies you want to pass. Ultimately it is going to come down to what sounds best to you, which is why we give you the option to turn this circuit on or off.