So... I upgraded the pickups in my Jazz Bass to DiMarzio Model J's and they sound great! I've been thinking about rewiring the bass so it has a master volume, blend pot, and a master tone (instead of 2 volumes and a master tone). I found a diagram for this, and the diagram shows 250K pots (which is what it has now). However, I've heard that you should use 500K pots with DiMarzios. As long as I have to buy a blend pot and take everything apart... it would be real easy to swap out the 250K ports for 500K pots.

I just wanted some opinions. What should I use with Model J's, 250K or 500K?

So... I upgraded the pickups in my Jazz Bass to DiMarzio Model J's and they sound great! I've been thinking about rewiring the bass so it has a master volume, blend pot, and a master tone (instead of 2 volumes and a master tone). I found a diagram for this, and the diagram shows 250K pots (which is what it has now). However, I've heard that you should use 500K pots with DiMarzios. As long as I have to buy a blend pot and take everything apart... it would be real easy to swap out the 250K ports for 500K pots.

I just wanted some opinions. What should I use with Model J's, 250K or 500K?

As a rule of thumb you should always use the value of pot the manufacturer recommends for a given pickup or system of pickups. If the DiMarzio wiring diagram shows 250K pots that's what they should be because the response and tone of the pickup is somewhat dependent on the loading of the volume pots. The exact amount of loading is determined by the values of the pots, the pickups were actually designed taking this loading into consideration. Keep in mind that adding another passive volume control as a master volume may increase that loading even a little more. You may wish to check with DiMarzio as to which pots should be used, both for the blend pot and the master volume. They may suggest using different values that are ideal for this particular application.

I don't know the answer, but I do know this topic has been covered quite a bit. If you haven't tried a search, I would suggest you do so.

Timely topic. I was on the phone with Dimarzio today with the same question.
They (was it Steve?) told me that it's completely personal preference. And it makes sense.

In my case I've got a Model J in the bridge position and a stock Fender P. Sounds good with 250k pots. ;)

500k are supposed to sound brighter and the lower the number the more it bleeds a bit of the sound off (atenuates, i think is the correct term).

Just what slaerts said:the higher the number the more treble allowed through, the lower the number the more bass.Both of mine have 500k stock and sound good.If you want more consistency you can get a few 250k pots and mod them like the Fender No-Loads so you dont lose treble as you turn your volume knob.I have a website where this guy compared a few different sets of pickups with 250 and 500k pots so you can hear the difference.

http://www.talkbass.com/forum/showthread.php?t=352658

Scroll down for some sound samples.

Thanks for the responses fellas. After readin them... I think I'll stick with 250K pots.

The Model J is somewhat dark, so 500K volume pots for me, and a 250k no-load tone pot.

The no-load tone pot takes the tone pot completely out of the circuit. Less loading on passive pickups, and a bit brighter. Mine are in a MIM-J fretless.