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Cool Tone Circuit Mod


orgmorg
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I have never really liked the way the typical tone control on a guitar just turns everything to mud, so I got to tinkering with it.

I usually use a .001 treble bleed cap with a parallel resistor across the vol pot. In this mod, the resistor stays put, but the cap goes between the middle lug of the Vol pot and the normally unused lug of the tone pot. Then I switch the other two lugs around, so the lead from the vol pot goes to the wiper of the tone pot, and the tone capacitor is on the lug that lead would normally go to. I don't know enough about electronics to really say exactly what is going on, but My guess is that as you turn the tone knob into the normally muddy zone, it passes some higher freqs back to the output, with increasing resistance. It really makes a huge difference, and turns it into a much more usable control. I like a .010 or .015 tone cap with it, but it works good with a .022 as well. I figured I would share it here, and maybe someone else could explain it better and even improve upon it, in terms of fine tuning it and such. Possibly it has even been done before, but I have never seen it.

tone_circuit2.jpg

Edited by orgmorg
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2 P90's with 250k pots. I initially had 500k pots, but the guitar was overly bright due to the body wood being oak, so I put the 250's in. That's really how this came about~ needing a usable tone control to moderate the piercing treble. It's nice to have that available for when you really want to cut through for a lead, but it is also nice to be able to turn the tone control down without sounding like your amp is buried in a pile of laundry.

It seems to work better with the 250k pots than it did with the 500k

I have also used it on a guitar with a P90 neck/Tele bridge (also 250k pots)

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if you really want to test it then doing it in the same guitar at the same time is the most effective way.

you could try it in a guitar with les paul style controls, 2 volumes, 2 tones... just use one of the pickups for the test and wire a switch to decide which pair of controls is in use

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Fluent A/B comparison within the same guitar is possible with a switch between wiper and clockwise lugs of the tone pot, since shorting them together reverts it to a conventional volume & tone circuit. Could for instance be done quick and dirty running two wires to a switch dangling outside, if you don't mind a little temporary hum picked up by those wires.

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Good point, but I don't have one like that, nor am I likely to. I would build one if someone requested it, but that hasn't happened yet, and I much prefer the 1 vol 1 tone setup for anything I build on spec.

I thought about putting one together just for test purposes, but I think what I will end up doing is building an outboard test station with a variety of switches and pots and such connected to alligator clips so I can easily swap out caps and resistors, and have two (or even more) parallel circuits to switch between. Then, before I do any final wiring in a guitar, I can wire the pickup switch straight to the output jack, plug into the test board and have at it. Then I can swap out components without soldering anything.

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Good point, but I don't have one like that, nor am I likely to. I would build one if someone requested it, but that hasn't happened yet, and I much prefer the 1 vol 1 tone setup for anything I build on spec.

I thought about putting one together just for test purposes, but I think what I will end up doing is building an outboard test station with a variety of switches and pots and such connected to alligator clips so I can easily swap out caps and resistors, and have two (or even more) parallel circuits to switch between. Then, before I do any final wiring in a guitar, I can wire the pickup switch straight to the output jack, plug into the test board and have at it. Then I can swap out components without soldering anything.

Absolutely brilliant. Added to todo list.

Has anyone done this before?

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this guy has lots of comparison vids - he just mounts the whole lot out of the guitar on cardboard

when i was comparing tone caps i used a beater guitar and i just taped the extra bits to the outside of the guitar body

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That's a pretty interesting video. It makes me really want to try this mod, too. I might have a go at it, it's time to change the strings on my HHjag anyway, and I've been wanting to mod one of it's vol. controls to spin-a-split. While I'm at it, I think I'm gonna try this out.

Edited by DarkAvenger
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Don't waste your time.

I went ahead and cobbed together a test panel like I was describing.

Set up this circuit, and a normal circuit side by side.

Spent some time switching back and forth between the two.

Not a bit of difference. :D

I think using the lower value caps (which does make a difference) is still new enough to me that I am hearing differences in comparison to the higher value caps in my head.

Maybe I need to start doing drugs again. B)

I guess the tone cap still offers a much less resistive path than the treble bleed cap, even for the freqs that would normally go through the latter.

Oh well, I'm learning something anyway, I suppose. :D

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one thing i found when comparing cap types was that there was very little difference in tones available - but there was a difference in taper, and therefore feel of the tone control. this made some easier to dial in than others and i suppose could lead to a perception of sounding better

i used a selection of new and vintage caps rated at 0.022, after going through and matching i ended up with a selection of caps that actually measured 0.02 and used them for tests. they were set up on the same pot with a switch to select which capacitor was used.

there was absolutely no difference in tone between the full on and full off settings, but like i said before, some rolled off gently, some suddenly.

so yeah, i think value makes much more difference to actual tone than the type of cap... even though i would have sworn differently last year

i still dont like ceramic disc caps as a general rule, they seem to vary from the stated value a hell of a lot more than the others i tried.

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Ya, I don't use the ceramics either. Mostly because they are percieved to be cheap/inferior. I don't mind shelling out an extra 50 cents for a capacitor to appease the voodoo gods. What gets me is the $20 ultra boutique caps. Even if someone specifically requested one of those and was willing to pay for it, I'd like to think I would refuse purely on principle.

But after doing this test, I totally see how people can really believe they are hearing these amazing tonal differences they get themselves psyched up for. Like: "Wow, man! I put these Mullard Mustard caps in my Strat and it totally makes my Peavey Bandit sound like a Marshall plexi!!" :D

The human brain is a never ending source of amusement.

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It's because of the tolerances probably. Ceramics are usually +/- 20%.

a lot of caps are stated +/- 20%, not just the cheapo ceramic discs. better ones are 10% which is still more than enough for quite a bit of tonal variation.... that's why anyone wanted to test them needs to match on values (something not done in the videos i linked to)

of all the caps i tested, the ceramics where the worst offenders. our of a pack of 10 0.022uf ceramic disc caps all were below 0.018 and some were as low as 0.014 - well out of stated tolerance! none of the other types (new orange drops and various vintage caps) were out of the stated tolerance, and they tended to be either side of the stated value rather than below

if anyone is after consistency its worth measuring pot values too as they can be just as bad. WD sell 10% ones at a little extra and some companies like BKP pickups also offer custom pots which are still 10% tolerance, but the stated value is 280k or 550k which means you never get one less than 252 or 500k - personally i prefer to get a batch of standard pots and grade them to match pickups/guitars or tone /volumes. no firm rules yet but i seem to be liking slightly lower than 500k for P-90 volumes

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  • 3 months later...

So let me get this straight my hand rolled, with killer beez wax by jamacian princess cap doesnt make me sound like Jimi?

Only if you get the ones that are rolled left handed.

fundamental freq of guitar on 24th fret aprox 1.35k. should i cut anything below that on my guitar? IMHO no. i dial most my eq pretty high on my guitars set them at the lowest to around 440hz there is no reason to set a tone control to .7hz. its not the tone pots resistance that determines the freq sweep its the volume pot on a standard setup. the tone pot is only a variable resistor to ground so essentially its a balance pot one side volume and tone roll off ie anything that is below a fundamental note is a volume control. and normal on the otherside.

f=1/2piRC for those who don't know it :D

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Talking of experimenting, prototyping and A/B comparisons, I recently started working on a few preamps and have found that using Molex KK and TE CST connectors has been a wonderful help as it is unbelievably easy to temporarily have flying leads out to breadboard or to swap components without constant soldering. Plus it allows me to make Wal-level tidy cavities!

:D

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