Pots resistance influence on sound and capacitor compatibility

[ppg]

I am going to buy new pots for my "new" MIM Jazz, which needs it badly to play properly. The question is, I found on net that there are different types of pots, the 250K one and the 500K (or even 1M) and in several discussions people said that the 25K will sound brighter and the 500K more darker sound. What do you think about using 500K on Jazz to "darken" it little cause I really dont need too much brightness. Does it need some additionals adjustmenst or you just wire it and thats it?

The second question is, there are different types of capacitors for tone pots, 022, 033 and 047 mf (what the hell mf stands for by the way?). Whats difference between them and which one would you choose (or HAVE TO choose) for 500k tone pot. Thanks.

[line6man]

Originally Posted by ppg

in several discussions people said that the 25K will sound brighter and the 500K more darker sound.

WHERE THE HELL DID YOU HEAR THAT!?

That couldn't be further from the truth.

First off, 25K pots should not be used in high impedance passive setups, as placing such a small resistance across the pickups is going to divert most of the signal to ground and kill a lot of output.

Second, 500K pots are brighter than 250K/25K pots.
When the volume is turned all the way up, there is a greater resistance from the signal to ground, so less of the signal is diverted to ground.
This gives you a hotter output and more treble.

Originally Posted by ppg

The second question is, there are different types of capacitors for tone pots, 022, 033 and 047 mf (what the hell mf stands for by the way?). Whats difference between them and which one would you choose (or HAVE TO choose) for 500k tone pot. Thanks.

mfd or uF stands for MicroFarad, which is a measure of capacitance equal to one millionth of a Farad.

The actual composition of the capacitor means nothing, as long as you choose one with a good tolerance. (I would suggest a film capacitor. I like Orange Drops personally.)
As far as the value goes, higher values cut lower frequencies, so the higher the value, the more treble cut.

0.047uF is the standard for most guitars and basses, though some like 0.1uF.

[ppg]

Originally Posted by line6man

WHERE THE HELL DID YOU HEAR THAT!?

That couldn't be further from the truth.

First off, 25K pots should not be used in high impedance passive setups, as placing such a small resistance across the pickups is going to divert most of the signal to ground and kill a lot of output.

Second, 500K pots are brighter than 250K/25K pots.
When the volume is turned all the way up, there is a greater resistance from the signal to ground, so less of the signal is diverted to ground.
This gives you a hotter output and more treble.

I read it few times on some guitar forums. I looked once again and I am pretty cofused about this: the normal pots have 250K and 500K or 25K and 50K??? I didnt mean to say "25 and 500", but "25 and 50" or "250 and 500" if you follow me.
You say that 500K will give you brighter sound, so 250K should give you darker, logically, or not?

For the modulators: I am just trying to find if I can modulate jazz bass sound into something more bassy and less brighter, because thats what I am worried about (I actually didnt have jazz before), so I am asking about this if this could be the way. I dont even know how much the difference in sound using said parts would be...

[line6man]

Originally Posted by ppg

I read it few times on some guitar forums. I looked once again and I am pretty cofused about this: the normal pots have 250K and 500K or 25K and 50K??? I didnt mean to say "25 and 500", but "25 and 50" or "250 and 500" if you follow me.
You say that 500K will give you brighter sound, so 250K should give you darker, logically, or not?

For the modulators: I am just trying to find if I can modulate jazz bass sound into something more bassy and less brighter, because thats what I am worried about (I actually didnt have jazz before), so I am asking about this if this could be the way. I dont even know how much the difference in sound using said parts would be...

Yes, 500K pots will be brighter than 250K.

[MglMatador]

For the modulators: I am just trying to find if I can modulate jazz bass sound into something more bassy and less brighter, because thats what I am worried about (I actually didnt have jazz before), so I am asking about this if this could be the way. I dont even know how much the difference in sound using said parts would be...

Moving down to a 250k pickup will reduce the magnitude of the resonant frequency peak that happens in the 3kHz to 4kHz range. Since there is 'less' signal at the peak, it will sound less 'bright' (in exactly the same manner as moving down a graphic equalizer slider at the same frequency). The peak will drop at least 6db.

If you don't want to change the magnitude of the resonant peak, you can also add to the capacitive loading of the pickup by soldering a small value ceramic or film capacitor in the 300-600pF range directly across the pickup leads where they attach to the volume pot(s). This will shift down the frequency of the resonant peak and will cause the peak to accentuate different frequencies. Also, since you are adding the caps to each pickup individually you can voice them differently: for example, make the neck pickup 'darker' with a cap but leave off the cap from the bridge. This will exaggerate the difference between the neck and bridge pickup positions, if that is what you are going for.

Try it and see what you think, there are a lot of possibilities there.

[Muaguana]

I'll take this as an opportunity to shamelessly promote my potentiometer thread...

Pot Shootout: 250KΩ vs. 500kΩ, audio vs. linear

Hear the difference for yourself, at least in terms of pot resistance.

[timmus]

25K pots are the norm in guitars with inboard preamps IIRC....250-500K in passive axes