Pots and caps

Not sure if this is the correct place but just I was looking for some info on pots and capacitors.
I’ve looked around and can’t find anything here. With pots I understand the ratings of 250,500K and a lot push pull etc but I don’t understand the physical differences between “normal” . There seem to be so many different threaded diameters, shaft diameters and base diameters. I have a tele kit and was looking to upgrade the pots and spent a lot longer than I’d care to say looking for ones with 6.5mm diameter shafts. I guess I’m missing something. I have 9mm pots I’m thinking of using and making the holes on the control panel bigger so they fit. Can anyone direct me somewhere that there is an explanation of how u can find what pots you need for specific guitars etc?

Also with capacitors i have basically found out in simple terms the higher the uF the “darker” the sound. Anyone have any recommendations for a tele with a neck humbucker? Or is it just a case of personal preference and experimenting?

Cheers


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There are two basic hole sizes for guitar pots: Asian (small) and US (large). Folks here like Bourne pots that use US size holes. CTS does as well. In fact the hole size is sometimes referred to as CTS sized. If you upgrade to those you'll need to drill or get a new plate. Alphas are probably amount the best quality Asian pots. They are fine in my experience and seem to be what EMG uses, among others. They are cheap enough to buy several and throw out any that are scratchy or spec funny, though I have not usually found that to be a problem.

.047 is a standard humbucker cap. It's a Tele so if you want it twangier, you could start with a .022. if that's too bright add another .022 in parallel to give close to the standard value. If that's too dark then you clip out one of the .022 caps and add a .01. Values are additive so two .022 caps in parallel are equivalent to one .044 (similar to .047).

Tele control plates are easy to take out, so easy to do some experimenting.

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The tone pot capacitor value is only going to make a difference to the sound when you turn the pot down. For any given pot value, you really won't hear any noticeable change in the sound with different value capacitors with the tone pot set to 10. The pot resistance value will make far more of a difference to the basic sound. For a given capacitor value, a 250k linear pot on 10 will give you basically the same sound as a 500k linear pot set to 5, so from that you should be able to mentally visualise that the tone pot value will have a direct effect on the brightness of the guitar. (You can get 'no-load' tone pots which have a break in the track so that at the 10 position, there is no path through to the tone cap, which is only connected once the pot is turned down to 9 or less. This gives a noticeable increase in treble).


Likewise the volume pot value will also have a noticeable effect on the sound, with the bigger the resistance the brighter the sound, as the pot value shifts the resonant peak of the installed pickup. The bigger the resistance value, the higher frequency that resonant peak is. The general rule is to use 500k pots for humbuckers and P-90s, and 250k pots for Fender style single coils. For a really bright sound (especialy if the pickups are on the dark side) you can use 1 Meg ohm pots, but above that, the resonant peak is shifted beyond the useful frequency range of a guitar (especially the limited ability of the guitar speaker to produce much output above 5-6kHz)

Obviously a Tele with a neck humbucker provides a bit of a challenge/choice as to what value pots to pick, as even with 250k pots, the bridge pickup on a Tele can be pretty bright, so 500k pots would exacerbate that. One compromise would be to use a 500k volume pot and a 250k tone pot. If the neck humbucker is a bright-sounding pickup (such as a SD Jazz or any old PAF emulation) , then sticking with 250k pots for volume and tone probably is the best idea. If the neck pickup is duller sounding, then 500K pots would be best to stop the neck pickup sounding too muddy when selected.

Remember that you do have a tone control, so if you go for a brighter basic sound, then you can always tame it with the tone control. If you end up with a dull basic sound, you can't do much about it except with the amp's tone controls. But you can't boost what isn't there, but you can cut what there's an excess of.

There is always the option of using 500k pots and wiring a 470k resistor between the bridge pickup output and ground. So when the bridge pickup or bridge+neck pickup is selected, the pickup(s) sees a 250k (approx) load to ground, but when the neck pickup only is selected, it sees the full 500k.

As Fender3x says, it's easy to remove a Tele control plate and try different values out. Just be aware that the control cavity rout on a Tele isn't that wide, and full-sized pots can sometimes be a bit of a tight fit (especially if the plate hasn't been installed along the dead centre of the slot) and that widening the sides of the rout slightly (say with a drum sander on a Dremel) might be called for.

Thanks for all that. This forum is full of great knowledgable folk


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Not sure if this is the correct place but I have another noob question about caps.
The pitbull tele wiring diagram shows to wire the cap like the photo above but I have see a few others with the cap connected to the volume and tone pots. Is there any difference or am I missing something.

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The tone system consists of a capacitor and variable resistor connected in series between a signal input and ground. It doesn't matter if the capacitor is first or the variable resistor is first; it works just the same either way round. The variable resistor is the pot, with just two connections - between the end of the track and the wiper connection. You can swap the two pot connections over, so it doesn't matter if the signal is connected to the end and the cap to the wiper, or the cap is connected to the track end and the signal to the wiper.

On the Northwest Guitars diagram, note that the wire leg of the capacitor is connected to the end of the track on the volume pot - but it is also used to connect that track end to the back of the volume pot - which is also connected to ground. So it is electrically equivalent to the PBG way of wiring.

You obviously don't have the ground connection from the jack socket to the back of a pot yet, or the output signal connection, or the pickup connections.

But what you really do need for best long-term operation is a ground wire link between the backs of the two pots. Because the Tele control plate is metal, you can get away with not having that wire as the plate itself will connect the two pots (as long as at least the back of one of them is grounded). But pots become lose over time, and they may become loose enough so that the connection between the pots is either lost or becomes a very high resistance, at which point the tone control (or volume control depending on which pot has the direct connection to ground) starts to play up, or you end up with a much noisier guitar. This is easily fixed by tightening up the nuts again - but it's not not something you want to happen mid-gig. So simply linking the back of the pots with a bit of wire prevents that happening.

The Northwest Guitar diagram method would mitigate against that to a large extent if the jack ground wire went to the back of the volume pot, as the cap would then be directly wired to a good ground, even if the volume pot nut came loose, so the tone and volume circuits would always work as designed (you'd just lose the shielding of the pot that the case normally provides). But it is best to have that soldered connection between the back of the pots for long-term piece of mind.