Talk to me about Pots and Caps

therose789

Can someone give me a really simple explanation of what they do and how using different values changes how your guitar sounds? 

ICBM

Pots:

The volume control acts as a variable voltage divider which controls the signal level, but it's also the main load on the pickup. Higher values give a brighter tone but worse treble loss as you turn them down. You can use either Linear or Log taper depending on how you want it to work - Log is generally better as a gain control for cleaning up an overdriven sound, Linear is generally better as an actual volume control on a clean sound.

The tone control acts as a variable resistance controlling the amount of signal that is sent through the tone cap. Higher values give a brighter tone when turned up full. You always want a Log pot unless you're going for a very specific, soft jazz tone when a lower value Linear can work well. (Essentially by turning the bottom part of the normal range into the whole sweep of the pot.)

Traditionally you use 250K for single coils and 500K for humbuckers, but there are some crossovers, eg P90s which work better with 500Ks because they are voiced more like humbuckers. You don't have to stick to the rules either, you can mix and match pot values with different pickups or with each other, eg a 250K volume and a 500K tone.

You can also wire up the connection between the pickup, volume and tone pots differently which affects how they interact. (50s wiring, modern wiring, independent wiring etc.)

Caps:

Larger values roll off more midrange - not more treble. All caps roll off treble, the size determines how far down into the upper midrange the effect goes. The useful range is usually .01uF to .1uF, although mostly you will find .022uF (with humbuckers) and .047uF/.05uF (with single coils) as the most common values.

Cap *type* and brand has no effect on the tone! At all. Not even a subtle, magic pixie-dust effect. This is provable no matter how many times you may hear people go on about how wonderful their vintage-style paper-in-oil (PIO) caps sound. Of course it may be that the values of poor-tolerance PIO caps are different from the more accurate modern ones, and that's what they're hearing… if they're not just imagining it.

Also important: the capacitance of the guitar cable can have a big effect on the tone of the guitar. It essentially acts as an extra tone control, permanently turned down. From an electrical point of view it's actually part of the guitar, because it isn't buffered from it. Shorter cables give brighter tone, and *sometimes* more expensive cables do too.

Does that help?

Skodadad

That was a very good post @icbm, the thing that stumps me is how does a single wire to the tone pot have any effect? Is the tone pot essentially drawing tone from the main signal and if so where does it go? I would understand if it was in line. I've always wanted to ask but as you can see am having trouble communicating what I mean.

ICBM

Skodadad said:

That was a very good post @icbm, the thing that stumps me is how does a single wire to the tone pot have any effect? Is the tone pot essentially drawing tone from the main signal and if so where does it go? I would understand if it was in line. I've always wanted to ask but as you can see am having trouble communicating what I mean.

It goes to ground, which is also connected - even though often not shown (or not shown fully - the connection is often 'assumed') on schematics. Yes, the tone cap is drawing high frequencies away from the main signal and sending them to ground, via the pot which controls how much.

That's actually one of the reasons the cap type can't matter, because any subtle differences in harmonics that could occur are in exactly the part of the signal that the cap is itself removing!

Skodadad

Ash yes of course! I never even considered the ground! DUH

Gassage

I cannot do this as I don't have a beard or an adenoidal voice.