G&L PTB Circuit (volume that cuts lows instead of highs)?

[333]

G&L's PTB (Passive Treble Bass) circuit features a bass cut control which removes frequencies starting at the lowest end of the spectrum and continues to remove them upwards making a stop at the low mids. (retaining the mids and highs)

I want the exact same thing only instead I want it to cut signal not just from the bass spectrum but to continue all the way through the mids and then through the highs until there is no more sound, and to use this as my volume control.

What I'm here for is a quick sketch up diagram if anyone has the time and kindness to help, thank you.



*I don't want a treble bypass cap nor 50's wiring, thanks*

 

[AlexR]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

The PTB works as it uses a cap to siphon off the lows......starting at a certain frequency determined by the cap. What you want is not a '1-control' operation with components.....as you would need several variable potentiometers each with their own cap and each coming into operation at a certain part of the circle.
Its more something that an algorithm and micro circuit board would be able to accomplish.

 

[gregory]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

Man you guys are just killing me here!!! Lows aren't "siphoned off" by a capacitor. That isn't even possible!

The bass portion of the PTB is a basic 1st order high-pass shelving filter. Lows are attenuated by the voltage divider formed from the bass pot and the volume control which the highs are allowed to bypass through the parallel capacitor.

 

[gregory]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

You might want to try replacing the volume control with something like this...

 

[333]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

You might want to try replacing the volume control with something like this...

View attachment 81659

I can read esoteric and astrological symbols but I haven't got round to electrical engineering, I assume this is a 1Meg pot with a 0.082uF cap but I still have no idea how it's wired, explain further details please? it's not just a treble bleed cap is it?

 

[gregory]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

The triangle is ground. The left side (input) comes from the selector switch. The right side (output) goes to the jack.

I have not tried it myself, so I can't vouch for the values, but they should at least do something.

If it works then try putting a tone control at the input.

 

[333]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

Ah yes, that's easy to read now.. look I can arrange some payment if yourself or anyone around can create a volume that cuts the lows before the highs, electrical engineering isn't my expertise so it would take me too long to work it out for myself.

 

[gregory]

Re: G&L PTB Circuit (volume that cuts lows instead of highs)?

It will work better with a buffer/active pickups in order to help avoid the inevitable tone suck once the pot drops below 500k, just that the bass and then mids will hopefully drop off quicker.

The 82nF is probably quite a bit high.