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Old 01-10-2018, 06:58 PM   #11
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St.Fill's Avatar
Join Date: Apr 2012
Location: Fla & Cali
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Originally Posted by Silimtao View Post
You're gonna have to hope that Fill sees this for the real technical advice.
Ha, I gotcha!!
(Thank you for that nice comment, Slim!!)

My explanations always seem to get long winded,. I know that some people here know this stuff already, but I have to assume that there are also some folks here that might NOT know, and would LIKE an explanation as to how this shit works, so here it is.
Originally Posted by DanRode View Post
I have 2 main questions. First, assuming 500k pots, what is the difference between .047 or .022 caps, and how would the treble bleed potential change that. Imagine something like Clapton's "woman tone". Do I want the neck and bridge the same?
First up... I've been a big advocate for "less than stock" cap values for a long time. Its been my experience based on a shit-ton of trial and error that a .01uF tone capacitor works better, not only when the tone control is 'off' (wide open, on 10") but it works WAY better, and is much more useable when the tone control is rolled back off of '10'. So my first comment would be to scrap the idea of a .022uF or a .047uF cap and go .01uF or even smaller, like .007uF but not smaller than .0047uF.

THAT being said, to answer your question as you posed it, IF you want to strictly go with something that Gibby would have put in a guitar, the .022uF cap is vintage spec.
Its (very) important to understand the relationship between a tone pots value (500k, 250k, etc), and how THAT affects what gets to the cap when the tone pot is NOT being used.

Simple explanation: A potentiometer is nothing more than a variable resistor. When the pot is on '10', the pots value determines how "hard it is" (how much it RESISTS) signal getting thru it, to the cap. The CAP is nothing more than a high frequency port, ITS value determining the range of high frequencies that it will allow to pass thru it, to ground, in a passive guitar circuit.

So a 500k pot on 10 will have 500k ohms of resistance to allow ALL the pickups available frequencies to get to the cap. The cap will allow "X" amount of HIGH frequencies thru it, depending on ITS rated value. (Note: if a tone circuit did NOT have a cap in its path, the tone circuit would act as another volume pot, since nothing would be in all the frequencies way to stop them from getting to ground).

The difference between a .022uF cap and a .047uF cap is that even with a 500k tone pot, the guitar will have slightly less highs with a .047uF cap than it will with a .022uF cap. Actual Gibson vintage guitars used 500k audio taper volume pots, and 300k linear taper tone pots, FWIW. I DONT think thats absolutely necessary, but that is what was in an actual '59 LP, 335, etc.

How does all this work with the treble bleed kit? The treble bleed will counteract the effect of the tone circuits load to some degree. In all honesty, I've never done an "A/B" comparison while playing around with tone circuits to see how MUCH it will affect that, but it definitely will.

The main feature of a treble bleed, obviously, is NOT to counteract the tone circuit, but to maintain the highs that a passive circuit loses when rolling back the volume control.
I dont use them in my guitars, simply because I WANT the tone to "dull" a bit when I roll back the volume. I like that tonal change, but thats just my taste in a guitars response. Treble bleed kits work as advertised, and I would not say "DONT put one in", because what works for me might not work for someone else, and vice versa.

Originally Posted by DanRode View Post
Next, is there somewhere I can buy matched sets of pots? CTS and Alpha are good quality but they vary. I want them as close to 500k as possible but it's more important that they test close to each other so both sets to respond the same. Otherwise, I have to buy a dozen pots, borrow a tester and hope to find some matching pairs in the group. I want to play guitar not test pots.
Originally Posted by DanRode View Post

For $99 I can get a solderless set from Obsidian wire. All the pots are within 6% of spec and matched within 2%. Switchcraft switch and jack are also included and connect solderless. It's 3x more but the soldering is top notch and it would take me 15 minutes to install.

Lastly, are there any other ideas or options I'm missing? Different components, values or wiring?
I sincerely believe that having pots within 10% of their rated value is a perfectly fine range to be within their rated spec. (FWIW, I have never seen a 500k pot that measured 500k on the button). A 500k pot thats between 450k and 550k (10%) is totally acceptable (IMO, anyway).

I check all my pots for total resistance on a volt meter and write it in marker on the side of the pots. I just took a quick look at a few of my "500k" pots (Alpha cheapies to CTS Emersons), and they range from 413k to 495k. The audible difference between those ratings is really minimal, if even detectable at all... I dont think thats a detail worth sweating over. Pot mfg's KNOW that we sweat shit like that, and they WILL charge you for your sweat, haha!!

However, the diff between installing 500k pots and 250k pots IS audible. Thats a difference worth considering when wiring a guitar.

I feel the bottom line is that long as its a high quality pot (CTS, CTS Emerson, Bourns, etc) the guitars circuitry will be reliable, and produce the results you're looking for. I've always maintained that circuit hardware (wire, pots, caps, jacks, switches, etc) is not the place to save a buck. There is nothing worse than scrimping on something like a pot or a pickup selector switch and having to rip the guitar apart again, to replace that pot or switch cause the pot has a dead spot in its rotation, or the switch doesnt make a connection in one of its positions. IMO, thats where a volt meter with a continuity setting is worth its weight in gold. You can find shit like that before soldering it in, AND you can check for continuity as you're wiring.

Not much worse than thinking you're "done", and finding out you're NOT done, cause a solder blob is touching something it shouldnt and the guitar has a short that went undetected... till you plugged into an amp.

The pre-wired kit you mentioned DOES have some validity if you want to make your life easier, and you want that control cavity looking nice and tidy. Obviously, the other side of that coin is being able to do precision work like that yourself, which IS a learning curve in soldering, wire routing, how much of this or that wire needs to have some extra lead so that maintenance is easier, what needs shielding, *which wires would be better off with a length of shrink tubing on them... (*GIBSON BRAIDED OUTPUT JACK WIRES!!! Learned THAT one the hard way TOO many times when wiring up a semi-hollow guitar ).

ANYWAY... hope that answered your questions, Dan. If not, shoot 'em out. If I know the answer (and you dont mind reading for a while), I dont mind writing for a while.

I used to develop and facilitate training meetings when I worked, and I edit College papers now for some students, so writing is one of my passions... clearly.

Originally Posted by DanRode View Post
If you were paying me to upgrade your guitar, would you want me to try to get it perfect or just shoot for good enough?
Exactly how I feel about helping someone with a question, assuming I know the answer to the question.
When I first laid eyes on you, I was transported to a place that only a fortunate few have been...
I was stupefied... transfixed... paralyzed... touched by angels. Never in my life...

Then, of course, you just HAD to speak, didnt you??
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