Another Tone Cap Question for Jbass

beyondat · #1 11-21-2010, 08:20 AM

Is it true that when the tone knob is fully open the cap has no effect on the sound? I had a RMC.1z 100v cap on my p-bass and it really cut a lot of the highs when turned all the way down which I liked. I want to put one of these on my Jazz bass but I don't want it to effect the highs when the tone knob is fully open. Thanks

iiipopes · #2 11-21-2010, 08:33 AM

All capacitors and all potentiometers that eventually go to ground in the circuit will affect the tone. The main way to lessen the loading to ground on your bass if you want to change out for the .1 mf capacitor is to change out the 250kohm tone pot for a 500kohm or 1meg linear taper tone pot. This will slightly decrease the amount of loading to ground, and will tend to counter using a higher value capacitor, while keeping a reasonable taper so the pot is actually usable through its range. Another way would be to change out the current 250kohm tone pot with a Fender "no-load" pot, so that when you have the tone control turned all the way up, it effectively disconnects the tone circuit so you get the full bore pickup through the volume knob, emulating, for example, original Strats that had no tone control on the bridge pickup.

Rant: with the availability of the no-load pot, I don't see the point with players who want just a volume knob on their instruments. If they play for any length of time (meaning years), whatever style the player plays, eventually some on-board tone shaping will be necessary, whether from change of style, to taking the twang off new strings for the first couple of hours of playing them after a change, to whatever. So the no-load pot can have a much broader use than just for current American Standard Strats to emulate original Strats.

**line6man** · #3 11-21-2010, 10:09 AM

When a tone pot is turned all the way up, it's placing it's full resistance between the capacitor and ground. This resistance is not infinite, so the capacitor is always cutting the treble to some degree.

There are two ways around this.

1. Get a no load pot or add a push/pull bypass switch to remove the tone from the circuit when you don't want it.

2. Switch to a higher pot value, so that there will be more resistance when the pot is all the way up. The downside is that if the value is too high, the tone control will act more like an on/off switch and won't adjust smoothly.

A 500K tone pot on full sounds very close to a bypassed tone control, IME. I could only hear the difference when the volume was on full, but once I turned the volume down some, there was no audible difference between the 500K tone on full and being bypassed.

**line6man** · #4 11-21-2010, 10:12 AM

Quote:

Originally Posted by iiipopes

The main way to lessen the loading to ground on your bass if you want to change out for the .1 mf capacitor is to change out the 250kohm tone pot for a 500kohm or 1meg linear taper tone pot.

You do not want a linear taper pot for a tone control!
Linear taper pots tend to act like on/off switches as tone controls. They do nothing for a large portion of the rotation, then suddenly kick in.

If you have a 1M pot, you especially do not want a linear pot, because it's not going to get into that normal 0-250K Ohms range until the last quarter of the rotation.

beyondat · #5 11-21-2010, 12:25 PM

Thanks, I'll try the 500k pot route since I have a few of these pots laying around. How would I know if my pots are Linear or audio taper?

**line6man** · #6 11-21-2010, 12:39 PM

Quote:

Originally Posted by beyondat

Thanks, I'll try the 500k pot route since I have a few of these pots laying around. How would I know if my pots are Linear or audio taper?

If the pots are marked, "A" would indicate an audio taper, and "B" would indicate a linear taper. (A500K, B500K, etc.)

If they aren't marked, use an ohm meter.

The halfway point in the resistance on a linear taper is at half the rotation. On an audio taper, it's around a fifth of the rotation.