Tone Before Volume Wiring

[minus.eleven]

I remember reading a thread where someone had done some serious electrical analysis regarding the circuit in a passive bass and its frequency response (anyone remember that? I think it had to do with a linear vs. audio taper discussion).

At one point, it was mentioned that having the tone control after the volume control caused them to be interactive - some kind of shelving effect, I believe. Correct me if I'm wrong.

For a simple p bass, I guess you would just take the hot from the pickup to the tone pot, and then also connect that hot lug to the input lug of the volume pot, and connect the output lug of the volume pot to the jack.

Has anyone had any experience with wiring it so that the tone is before the volume? Are there any downsides?

[walterw]

les paul geeks call tone-after-volume "'50s wiring", where the tone is connected to the volume pot's center lug, (output) rather than the clockwise lug with the pickup, (input). it makes for a slightly cleaner sound when the volume is turned down, but at that point requires the tone knob to be turned way lower to have any effect.

on a p-bass, tone-before-volume is normal stock wiring.

now that i think about it, i guess stock jazz bass wiring would have the tone after the volume, wouldn't it? i'll have to mess with one and see if the effect is the same, that is, whether turning both volumes down a little causes the tone knob to be less effective.

[slyjoe]

On a standard P-bass, the "before" and "after" doesn't really have any meaning - they are in parallel.

If you mean the the output jack is tied to the volume, that is true, but it doesn't mean one is before or after the other. The pickup hot goes to the lug of the volume AND the tone, and the center lug of the volume goes to the output jack.

[walterw]

Originally Posted by slyjoe

On a standard P-bass, the "before" and "after" doesn't really have any meaning - they are in parallel.

you're right, of course. "before" or "after" is a clunky way of describing what's going on.

[slyjoe]

walter - based on some of your other posts, I figured you knew what was going on.

It IS a little different on a jazz - there, the pickups go to each volume pot's wiper first instead of the lug that connects to the tone pot.

I think I remember the thread the OP may be referring to - there was a discussion about connecting each jazz pickup to the "top" lug instead of the wiper lug of its volume pot, and sending the signal from the wipers to the top of the tone pot.

[bassbenj]

Originally Posted by walterw

les paul geeks call tone-after-volume "'50s wiring", where the tone is connected to the volume pot's center lug, (output) rather than the clockwise lug with the pickup, (input). it makes for a slightly cleaner sound when the volume is turned down, but at that point requires the tone knob to be turned way lower to have any effect.

Passive wiring is a kind of trick and often a compromise. The deal is this. The pickup is an inductance plus a series resistance (resistance of the wire). Plus the inductance sees the resistance of the volume control plus any loading from the amplifier. Generally an R and a L form a kind of high cut filter that rolls off highs. The tone control on the other hand is a resistor (pot) plus a capacitor. That circuit is an R and C which also rolls off highs as the resistor is made lower in value.

The problem when either the pickup or the tone pot is connected to the slider (center lug) on the volume is that in turning down the volume that resistance goes to zero (or very low). So what happens is that either volume settings change the tone of the bass (as happens in my OLP MM Vol/vol wiring) or as in the "50's wiring" mentioned above where the tone control is greatly affected by the volume setting.

Active circuits solve a lot of these problems. But passive wiring has sort of developed standards which people have become used to even if they do tend to interact sometimes. A lot of guys just live with it because they like the other things it does (like my MM).