Fun with guitar vol/tone circuits

[MWaldorf]

Having a couple of gigs with the Hallmark under my belt, I decided to start futzing with the vol/tone circuit. The stock was a 250K volume and a 250K tone pot, with a 0.047uF capacitor (I could be wrong on this; I didn't measure the stock cap value). I replaced the 250K volume pot with a 500K pot, which allows more high end to pass through, and I put a 500pF capacitor across the sweep as a treble bleed, so the tone stays bright as you roll off the volume.

Next, I replaced the stock tone pot with a Fender TBX stacked pot. These are very interesting, in that you've got a 250K pot that goes from 0 to 250K in half the sweep (full counter clock-wise to center), and a 1M pot that goes from 0 to 1M in the other half of the sweep (center to full clock-wise). The stock TBX arrangement allows you to create a fascimile of a no-load tone control, which is fine, but it can also be set up to work as both a treble and a bass cut, using the circuit below, which I found through the magic of google:



This makes the tone control a treble roll off from 5-0 (full roll off at 0) and a bass roll off from 6-10 (full roll off at 10) At the center, with a convenient detent, it's like the standard tone control on full. I wound up using a 0.001uF capacitor on the bass roll off for a more dramatic effect. I got the TBX on eBay for about $15, plus a couple of bucks for some different capacitors from RadioShack. Note that the TBX uses a standard sized pot shaft, so you'll have to drill out the Hallmark knob sleeves a tad to get them to fit.

So, what does this all sound like? Pretty cool I'd say. The full volume setting has more presence and the treble bleed cap keeps the tone pretty consistent across the volume levels. The TBX really makes a big difference - by rolling off the bass, I'm able to get more Fender-y tones. This is especially useful to me on the "Strat" settings, ie neck+middle and middle+bridge, but it's also useful in the other pickup settings when I want less beef in the tone.

Here are pictures of the installation:

[Dennisthe Menace]

Hey Mel, that's a WILD Set up!. How does the Mids tolerate this when you roll off the Bass??

[Veenture]

Pretty neat presentation Mel!

[MWaldorf]

Hey Mel, that's a WILD Set up!. How does the Mids tolerate this when you roll off the Bass??

The bass roll off is very similar to the "thin switch" on a Fender Jaguar, except it's a pot instead of a switch. You can vary how much effect it has by using a different value capacitor. When the knob is on full, the signal only passes through the capacitor, and the smaller the value on the cap, the higher the frequency of what is passed through. A Jag uses a 0.003uF cap on the thin switch. I initially tried a 0.0047, then a 0.002 and finally the 0.001 that's in there now, each resulting in a "thinner", less bassy sound. There's a drop in volume, but it's still workable.

[Vec]

Cool idea MW...I'm considering doing something similar to my next Custom 60. I'm considering doing a dual gang tone pot but one that has separate controls for bass & treble so they can be adjusted independently if need be. I'll keep you posted on the results if my project ever gets off the ground .

[MWaldorf]

Cool. There's a schematic for that at the bottom of the discussion where I found the TBX mod:

http://www.tdpri.com/forum/tele-tech/35794-tbx-rewire.html

[oipunkguy]

this is awesome. I had no idea that the TBX was a one meg valve on the other side.

[Sarah93003]

Very cool! Thanks for sharing that!

[101Volts]

Though the thread's several years old and the images are gone now, I thought I'd bring it up for discussion.

Are there any push-pull potentiometers that have a 500k value in one setting and 1 meg in another?

Austin

[panther]

The only ones I'm familiar with are 500K. But if anyone has them ore a wiring diagram needed, it's these guys. Look around they have hundreds of different configuration. You could spend all day just thinking about what to do.
Dan


http://www.guitarelectronics.com/