sorta off topic... treb and bass mod for les paul (and other) guitars

[pinkjimiphoton]

hi guys,
i was browsing joe gore's tonefiend site recently, and came across a demo he did of a hamer that had been modified to have volume/treb/bass instead of the original vol/vol/tone.

i really dug how you could clean up the dirt with the bass control, and figured i'd give it a shot. i wanted to do it in my les paul, which is a very dark sounding axe...
first i tried the layout he'd drawn, but it wasn't matching the schematic he'd posted in values or connections, and it just plain didn't work as he'd drawn it... of course, i'm keeping the two volume controls, so i had to take my output from the switch instead of the input to the pot.
this would work on strats or any guitar with at least three knobs, and is a really cool mod. in my case, each pickup has it's own volume control, the top previously tone control becomes a treble cut (pretty much a standard tone control, with the "woman tone" kind of feel) and the bottom one becomes a bass cut. VERY cool. i drew the attached pic as i wired it in my guitar, but you may find it to be counterintuitive as shown... in my layout, as you turn up the control, you cut bass... which cuts the balls somewhat. wire it backwards, and the balls will increase as you turn it up. your choice.
with the bass limited, fuzzes and distortions (or tube amps) will seem to have more cut, and you can basically make a les paul sound like a telecaster or strat... it's pretty cool!!! the neck pickup gets that liquidy hendrix neck tone, and the bridge can go from strident to phat.
the tonal combinations may be worth it to you... it's a simple mod, all ya need is a little wire and a couple caps; you can use the pots already in the guitar!
and if ya don't like it, you can change it back really easily.

i'll try and shoot a stupid pedal trick soon as i can... here's the wiring diagram:



if ya try it, let me know what ya think.

when the bass pot is all the way down, it's stock sound (as is the treble all the way up). no - load pots may be even cooler, as they give another option.

rock on!

[wavley]

You know, years ago I ditched the bass cut on my Jaguar in favor of series/parallel switching for the pickups and the bass cut switch became a polarity reverse for the bridge.  I rarely used the bass cut, but I never use the polarity reverse.  I had thought of installing a tiny pot in the hole where the switch goes for a variable bass cut which would be awesome for the humbucker mode because it gets a bit flubby sometimes.

You gave me the kick in the pants I needed to do this maybe.

[pinkjimiphoton]

it really works well, wavely...
and it's great with fuzz and distortion. i'm glad it may inspire you to play with it. different value pots may work better, but the 500k's in my les paul seem to work really well!!

[space_ryerson]

Hmm. I have a super-bassy old LP custom that might benefit from this. I was thinking of trying an inductor mid-cut, but this is free, so I'll try it first

[bluesdevil]

Goddamn, that's cool!!! Thanks for sharing. Sounds better than a split coil switch thing for thinner sounds.
I would love to try it in my ol' Les Paul, but I think I will have problems with possible mismatched tone pot values due to an active pickup in the bridge.
Maybe I can still use it in another guitar soon ... thanks again!

[SmoothAction]

Hey thanks Jimi. I have a Gibson LP studio (stock) that is pretty dark sounding any way you slice it. This may be the fix Im looking for.

[skumberg]

This is how G&L does it on their legacy and s500 guitars. I think it was introduced with the s500 in 1983.
http://www.glguitars.com/schematics/Legacy_schematic_blockdiagram.pdf

I like it in my legacy tribute and as you say rolling of the bass is interesting for experimenting with fuzz pedals.

[Mark Hammer]

Reverend does that too, with their Contour control.

One of the things I like to do is use an "overcompensated" Volume pot.  Typically, we usea small-value cap to jumper the input lug and wiper of a volume pot, sometimes with a series resistor in addition to the cap.  The intent is to retain a bit of the top end to compensate for the loading down of the pickup as the volume is turned down. 

The "compensation" provides an express route for the top end so that it bypasses the attenuation of the volume pot.  If you use a larger cap value, though, like 1000-1500pf, you provide a bypass for not only the top end, but the upper and middle mids as well.  The volume pot now starts to function like a bass cut between 6 and 10, and a volume pot once you turn down below 6.  Not for everyone, but it works.  Can be especally effective on bridge humbuckers, and "de-thicken" them nicely for chicken-pickin.

[pinkjimiphoton]

Goddamn, that's cool!!! Thanks for sharing. Sounds better than a split coil switch thing for thinner sounds.
I would love to try it in my ol' Les Paul, but I think I will have problems with possible mismatched tone pot values due to an active pickup in the bridge.
Maybe I can still use it in another guitar soon ... thanks again!

bill, if you're using this in a guitar with active pickups, it should be fine... this is designed to go AFTER the pickup switch bro. may work BETTER with active p'ups!

[pinkjimiphoton]

Hey thanks Jimi. I have a Gibson LP studio (stock) that is pretty dark sounding any way you slice it. This may be the fix Im looking for.

my epi quilt top standard was a great guitar, but CRAZY dark sounding... now i can dial it in to any tone i need, and actually use it on stage finally...
can sweep from les paul phat to almost tele crispness, even get close to a strat neck tone with the bass dialed out.
and you can sweep in however much distortion you want with your pedals from the guitar.

and it will work on strats or whatever, too.

[pinkjimiphoton]

This is how G&L does it on their legacy and s500 guitars. I think it was introduced with the s500 in 1983.
http://www.glguitars.com/schematics/Legacy_schematic_blockdiagram.pdf

I like it in my legacy tribute and as you say rolling of the bass is interesting for experimenting with fuzz pedals.

i stole it from joe gore (from "tonefiend" and GP magazine fame) who indeed stole it from the g&l guitars.

i wonder why every guitar doesn't have one.. i didn't realize it in the past, but i had a 3 pickup hollowbody kay with one of these controls on it many years ago...and that guitar was from maybe 1950-52. so it pre-dates leo's version.. in that case, a 1meg pot... but i don't remember the tone control values at all.

[pinkjimiphoton]

that's a great tip, too mark.
i find anything over about 150p is too much for me in that use, but i had used that big a value a long time ago.. very brite on my sg... too bright, as THAT guitar needs more of a bass boost cuz it's so brite already.

thanks guys... hope these mods are useful to someone! they're not mine, just trying to spread 'em around cuz i found 'em to be really useful.

[Ben N]

Wavely, I found the strangle switch on the Jaguar pretty useless and was looking for a good alternate use, too, but I sold it before I got around to changing the wiring. The difference is that it was an all or nothing proposition, and on pups that were already on the thin side. By making it variable, you make it useful, and on humbuckers... well, that sounds like a good idea. I bet it would go well with P90s, too.

[pinkjimiphoton]

with p90's, you can dial out some of the woofiness, and then dial in exactly as much grunt as you need.
i've gota a "strat" with a p90 at the neck, and a p100 at the bridge... seriously thinking about adding these controls to it, and moving the pickup switch (which is between the vol and tone pots)

[wavley]

Wavely, I found the strangle switch on the Jaguar pretty useless and was looking for a good alternate use, too, but I sold it before I got around to changing the wiring. The difference is that it was an all or nothing proposition, and on pups that were already on the thin side. By making it variable, you make it useful, and on humbuckers... well, that sounds like a good idea. I bet it would go well with P90s, too.

Yeah, but when I have it in both pickups in series sometimes I really miss it, plus I had Curtis Novak wind me some pickups that are considerably thicker sounding.  Variable is definitely the way to go.

[Mark Hammer]

I've mentioned this idea before, but perhaps not in any thread where it could gain traction.

Take a look at the tone control for the 5F2-A tweed Princeton, or similar amps ( http://www.freeinfosociety.com/electronics/schemview.php?id=802 ).  It is essentially a standard guitar treble-bleed control AND a variable volume-pot compensation in one control.  

In that amp, the volume pot is 1meg and the tone pot is a second 1meg pot, with its wiper tied to the input of the volume control.  One end of the tone control goes to a 500pf (470 or 510 in current parlance) that is, in turn, tied to the volume wiper.  The other end of the tone pot goes to a 5000pf cap to ground.  Rotate fully in one direction and you have 500pf straddling the volume input and wiper, with 1meg between the volume input and 5000pf treble-bleed cap to ground.  Rotate fully the other way and you have 5000pf to ground from the volume input, and 1M in series with 500pf between the input and wiper of the volume pot.

Like all volume-compensation caps, there is no effect of the "bright cap" when the volume is up full.  It only has an audible effect when the volume is turned down.  Of course, the principle difference between a guitar volume pot and an amp volume pot is that one is nearly always up full, and the other is nearly always closer to the bottom.  So this tone arrangement provides noticeable brightness in those amps where it is used.

However, that is not to say it couldn't prove useful in a guitar, as a treble boost/bass-cut  and treble-cut control.  My gut sense is that if one were to implement this with a 500k tone pot, the cap shown in the 5F2-A as .005 would need to be .01 to .02uf, and the cap shown as .0005 would need to be 1000-1500pf.  There would also either need to be a very particular pot taper used, or else one would stick a parallel resistor between the tone pot wiper and suggested 1000pf cap to provide audible tonal change within a reasonable portion of the rotation.  This would allow one to dial in some of the bass cut with the bypass cap having little or no series resistance, and the volume turned down a bit, or turn the pot the other way for traditional treble cut.  Note that the treble-boost/bass-cut only works when the volume is at less than max, but the treble-cut works at any volume setting.

I've tested it out, and it "works", but tweaking the tone-pot taper requires some trial and error to work acceptably.

[lion]

Hi Jimi and all
Just a thought. As far as I can see there's a significant difference between Jimi's LP circuit and the GL, with respect to the bass cut function.

In the GL circuit C1 forms a RC/High pass filter with the Vol control VR2. In Jimi's circuit the cap forms a filter with.....  - whatever input impedance (?) you plug into!
Meaning the function of the bass cut control will depend on outboard specs - might not be a problem, but probably not ideal. An alternative would be to use the bass cut on the neck pickup only and connect it ahead of the N-pu vol control giving a fixed R value.

Maybe I'm missing something?

Erik

[pinkjimiphoton]

hi erik,

beats me, maybe that's why it is far more noticeable into distortion than a clean amp?
clean, it's pretty subtle... into fuzz it's pretty sublime!!

on the neck pickup, it makes it sound more like a strat neck p'up.

in the bridge, you can get more into tele or almost rick kinda sounds. i did notice there's a low end "presence" that is affected, but no idea how that's working, so i'll take your guess as probable!