Capacitor position question for Gibson SG

[BackinBlack]

HI There
On the web in multiple places for 50's and modern wiring diagrams for Gibson SG's the capacitor 0.022uF is often shown connected between the middle leg of the volume pot and the outer leg of the tone pot. Why does the pitbull wiring diagram for "Two Humbuckers to 2 Volume, 2 Tone and a 3 way Switch" show the capacitor wired across the tone pot legs only (middle leg and ground) and its 0.047uF rather than 0.022uF?

how much difference will this make to how it sounds?

thanks for any help

[Sonic Mountain]

Basically there are multiple ways to skin the cat when it comes to wiring up guitars and they all do slightly different things or do the same thing different ways.

There is no hard and fast rules as to what cap you use. You are right that a 22uf is more common with humbuckers, but using a 47uf doesn't change functionality that much, generally just makes them sound a bit darker, which might suit the kit humbuckers better in this case.

Same goes for current flow, you can route it different ways and still have a working circuit.

Really the only way you'll get to know the different nuances is by trying different things and seeing what you personally like.

Understanding the functions and principles of each component is a really good way to start, all the controls are doing is managing the signal path from the humbuckers to the output jack. Once you get your head around that, troubleshooting and modifying the circuits becomes much easier and from doing that you'll start to understand how different wirings and components affect the final signal.

[McCreed]

Ditto to Sonic’s reply.
In regard to testing cap values to hear the differences, LP’s make this easier than say a strat because of access to the control cavity being in the back.
You can connect caps of various values with alligator test leads to the appropriate pot lugs, play the guitar while adjusting the tone(s) up & down, then clip in the next value and so on.
Once you hear what you like, solder it in and Bob’s your uncle.

[fender3x]

Ditto to Sonic’s reply.
In regard to testing cap values to hear the differences, LP’s make this easier than say a strat because of access to the control cavity being in the back.
You can connect caps of various values with alligator test leads to the appropriate pot lugs, play the guitar while adjusting the tone(s) up & down, then clip in the next value and so on.
Once you hear what you like, solder it in and Bob’s your uncle.

I think this is great advice. The little "chicklet" caps are cheap. It is good to get the common values between .01 and .1 so that you can try them and see what you like best. On my last build I had heard that .047 might be best...or maybe .022... What I thought sounded and rolled off best was a .033... Which I have seen is some old Gibson wiring diagrams. Now I know why.

BTW, my last build was strat style. To be able to try a few different values without removing the strings and pickguard, I wired the cap under the jackplate.


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[McCreed]

BTW, my last build was strat style. To be able to try a few different values without removing the strings and pickguard, I wired the cap under the jackplate.

Yeah, as much as I love strats, they can be a pain in the bum that way for testing caps or other things. I have run test leads out from under the pickguard, leaving a few of the bottom screws out the guard for the testing. Of course it still requires string removal at least twice, but it minimises some of the mucking around at least.

re: .033 caps, I have used them in a lot of my guitars for about 15 years now. I think they give a good, more usable, range.

[Simon Barden]

The tone pot has two connections and is being used as a variable resistor (unlike the volume pot which is wired as a potential divider and has three connections). The tone circuit is the variable resistor and capacitor in series between the output signal and ground. You can have the capacitor and resistor either way round, it works just the same.

The capacitor will pass the high and most of the middle frequencies but will stop passing the bass frequencies depending on its value. The bigger the value, the lower down the frequency range the signals start to get blocked. So with the tone pot on 0, there is no resistance between the capacitor and the pickup signal, so most of the upper frequencies get grounded, leaving only the bass frequencies being passed on to the amp, and hence the dull sound. With the tone pot on 10, you have the full resistance of the pot reducing the signal level going to the capacitor, so almost all of the pickup's output is sent to the amp.

0.022uF is the 'standard' modern capacitor value for humbuckers, as these are normally darker sounding than single coils, which will generally have 0.047uF capacitors, so that when rolled off, both types of pickups still have enough low-mid frequencies left to make the notes sound bassy but still distinguishable. But what you like your tone control to do is very subjective, and not everyone likes the dull tone that full tone roll-off can give. If you are never going to use it backed off that far, why have it set up for that, and why not have a less aggressive tone control arrangement? So I now generally fit 0.015uF capacitors. Which still gives allows quite a dull tone, just not that dull. But it is a personal preference, so really you should try some different values and make your own mind up what works for you with a certain pickup type.

Gibson have used 0.1uF, 0.047uf, 0.033uF and 0.022uF caps on humbuckers for their tone pots in the past. 0.022uF has been their cap selection for many years now. But remember that Gibson came from a jazz guitar background, and the Les Paul was originally designed to be a jazz guitar, so Gibson needed it to be able to get very dark and mellow sounding, hence the larger value caps on the earlier guitars.

Note that the tone capacitor value will make zero audible difference with the tone control set to 10. There is some very minor treble roll off with bigger value caps, but you'd need a spectrum analyser to detect it as it's in the order of a 1/8dB level difference between 0.047uf and 0.022uf at the higher frequencies. You'll probably roll off more treble by having a guitar lead that's a few feet longer than your standard length.