Treble Bleed off mod for PRS Custom 22, Help

[NOVA70]

Hi,
I just got a new PRS Custom 22 Artist that I would like to install a treble bleed off mod. I noticed that there is a capicitor on the volume control already. It has the 5 way rotary switch. I tried installing an 100 ohm resistor but I found it to be to bright. Does anyone know the value of the cap PRS installs or have any recommendations on how to do this?
Thanks,
Pat

[Clorenzo]

As you said PRSs already have a treble bleed circuit, consisting on a single 180 pF cap accross the in and out lugs of the volume pot. Another typical circuit is a 150 kOhm and a 680 pF cap in parallel.

The single cap moves the pickup resonant peak up in frequency as you turn the volume down, so not only does it prevent the usual treble roll-off, but also gives a different flavour (more single-coilish) to the pickup tone.

The cap + resistor basically keeps the frequency response constant so the tone doesn't change noticeably.

To see the effect of these two options or others you may want to try, you can use my volume and tone simulation spreadsheet available here:

http://harryjguitar.com/voltone.xls

Please read the first page for instructions. As explained, if you want to simulate just a capacitor in the bleed circuit, give the resistor a very high value such as 1000000 kOhm.

[NOVA70]

Thanks for the help Carlos, I'll try the 1000000k resistor.
regards,
Pat

[Clorenzo]

Originally posted by NOVA70
Thanks for the help Carlos, I'll try the 1000000k resistor.
regards,
Pat Sorry, I think I wasn't clear: The 1000000k resistor (that would be 1 Gigaohm! :eek: ) is just the value you have to enter in the spreadsheet to simulate that there's no resistor. You are not supposed to put an actual 1Gohm resistor accross the pot. I don't even think such a thing exists!

[NOVA70]

Hi Carlos,
I went to Radio Shack and got a 1 megohm resistor and a 10 megohm. Which should I use?
Regards,
Pat

[Clorenzo]

Hi Pat,

Let me try to explain this again: the cap that you have now in the volume pot IS a tone bleed circuit itself, you don't need to, and you shouldn't, add a resistor. If you like the way it works, just leave it like that.

If you don't like it because it makes the sound too trebly when you turn down the volume but you still want to avoid the treble roll-off, you can remove the existing cap and replace it with a 680 pF cap and a 150 kOhm resistor in parallel, i.e. both soldered between the pot lugs where the current cap is soldered. This will give you a more linear effect.

Hope this makes it clear,

[NOVA70]

Yes it does , thank you. I have added This type of mod on 2 of my other PRS Single Cuts from a schematic I got from Seymor Duncan, but those guitars did not have any caps at all on the volumn control. What confused me was the exsising cap by PRS. I thought I could add the resistor and accomplish the same. I use tube amps (Komet) so the volume control is in use alot. I noticed with this guitar when you roll it down it tends to get bassey sounding that's why I thought I was missing something by not having a resistor on the volumn control. Thanks for your help.
Pat