Wednesday, January 19, 2011

Treble Bleed Mod

In this post, I would like to present my way to make a good guitar treble bleed mod (treble bleed prevention). If you were searching on-line about this circuit, you probably know what it is, and that it can be made in many different ways.

If you don't know what it is...
The treble bleed mod is a circuit which can help you keep the treble in the guitar signal, when you're turning down the volume potentiometer.
Probably you know, that when the volume pot knob is turned a little bit down, the guitar signal is quieter and also darker or smoother – it's loosing some high frequencies. Treble bleed mod will help in preventing treble frequencies from bleeding to the ground.

It's made from capacitor, or capacitor and resistor in series or parallel. It should be connected to the input and the output lug (firs and middle) of the volume potentiometer .

There is no perfect treble bleed prevention for a passive circuit. For example:

1. You made some treble bleed mod. Now, your guitar sounds good to you with the volume knob on „5”, but on „3” the tone is too bright and harsh.
2. You decided to change parts for different values. Now, you have a nice, clean tone on „4”, but on „6” or „7” it's too dark.
3. However, it is possible to make an 'almost perfect' – 'well balanced' treble bleed mod. It just need experiments.

My way:

I like to make a treble bleed preventing circuit by using a capacitor and a resistor in series.
This is how it looks like:

How it works? 

The resistor in this circuit works similar to the potentiometer in the tone control. It's regulating how much of the signal will pass the line. 

The capacitor got affect on what frequency level will pass the "RC bypass". Higher value = more treble in the signal.

The treble bleed mod can be made from a capacitor only also.

If you made the mod only with a cap, it will be probably quite unbalanced. On some knob positions your tone will be too bright, on some still too dark, on some just like you want. From the other side, some folks like this unbalance.

BTW, remember, the pot case must be connected to the ground.

My experience:

I made this mod in the guitar with PAF-style humbuckers and 500K pots. I discovered, that I like to use a 24K resistor with a 560pF or 680pf capacitor.

When I'm turning down the volume pot knob, the tone becomes quieter (of course), not too dark, but still quite smooth and well balanced. The 24K resistor is helping me especially on really low volume levels. Without it, my quiet tone was too harsh and „cheap”. With it, the capacitor is not adding too much of treble, so I have quite good balance between all frequencies.

Remeber, you need to test few values of parts before you get what you want.