Taper In Relation To Pot Value?

[j. pierce]

I recently wired up one of builds, and even though the pickups were single coil, being that all I had in my parts bins where 500K? pots, I used those. Now the odd thing is, the usable sweep seems to be bunched at the end of the taper - that is, volume drops off very quickly as I begin to roll it off from 10, to where it's basically silent (unless the gain on my amp is up rather high) very quickly. (Around 7 or 8? I'm not exactly sure. But very quickly into the sweep.) If I'm just going to set and forget, it's no problem, but it's too finicky for whilst-playing adjustments.

My first thought was that I hadn't used Audio taper pots, but I went back and checked (both the codes on the pot and with a multimeter) and they are audio-taper - is this a side effect of using a higher value pot than needed? Will switching out to 250K? pots help me out in this regard?

Thanks guys.

[JoeAArthur]

I wouldn't think it would be either taper or value. I've had Tele's with 1 meg audio pots for volume and had a pretty even sweep throughout the range.

Is is possible the control is wired backwards - meaning the center terminal is connected to the pickup or pickup selector and the output is taken from what would normally be the hot outside terminal? This type of connection, while it will work, loads down the pickup as the volume is reduced which doesn't happen with the normal connection.

If not... what is connected between the center lug of the control and the output jack? You might turn the pot to halfway and measure the center terminal connection to ground - a lower than expected resistance here (i.e. less than 40-50K) could give the action you are describing. If some other connection isn't loading the circuit down at this point... it could just be a bad pot.

[j. pierce]

Is is possible the control is wired backwards - meaning the center terminal is connected to the pickup or pickup selector and the output is taken from what would normally be the hot outside terminal? This type of connection, while it will work, loads down the pickup as the volume is reduced which doesn't happen with the normal connection.

Bingo. Don't know how I managed to do that, but yeah, that's the case here. I've done enough of this type of wiring, you'd think I'd get it right. Or notice it when I opened the thing up.

Thanks!

.j

[bssist]

I just found this site while looking for the cause of my very similar problem. I am a bit confused on why this is and how to overcome it. My understanding is that on a two pickup instrument (I just finished my PJ bass) the volume pots are wired backward to keep from shorting out the amp input and dropping the output of the second pickup if one is turned all the way down.

Do I not understand the theory correctly? What can I do to overcome these issues.

Just for reference - I got my theory info from stewmac.com.

Thanks for the help!

Murf