definitely try 500k first. 1M pots are an option depending on the guitar though. i've used them in the past and they can brighten up a dark sounding guitar with high DC pickups.
philking told me 2M pots would be overkill... anyway, i tried them - and he was right ;) very piercing brittle treble with 2M pots.
Okay, now this I don't understand. If you wire up your guitar so the pickup goes straight to the jack socket, do the trebles also sound very "brittle and piercing"? (I'm asking about this specific guitar). My understanding of it is that the lower impedance pot will roll off more of the treble than a higher impedance pot. So surely with no pot at all, the impedance of "the pot" is infinity, and the trebles are "natural" - any pot put in place will take the trebles off relative to this state. Am I missing something here? I guess my point is that the pot can't add treble, it can just take less away!
Please do correct me if I'm mistaken about this!
Roo
ok.... "very" was an exaggeration on my part, "slightly" would have been closer to the truth.
in the case of the specific guitar:
this was a soft maple flying V with at that time cold sweats. there was originally 300k pots in that guitar, which was definitely too dark. i found 500k also dark. i went to 1M and found it was almost ok, but i wanted a bit more brightness. trying the 2M it was clear this was a bad decision - the treble was quite spikey, and it didn't have any more definition in the bass end than 1M. the quality of the 2M pot itself was also a little disappointing - i ordered it from torres and was expecting CTS like quality - actually it was an Alpha pot. the difference between the pot values going 300k->500k was subtle but noticable. the 500k->1m swap was obvious. the 1m->2m swap just made the treble nasty sounding.
now - what i actually needed in that guitar was not more treble, but less bass. increasing the value of the pot helped to a certain extent, but it didn't really solve the problem.
i kept that 1M pot, and tried various other pickups, including a rebel yell which was ok. last weekend i tried a VH2 in that guitar, and the treble was too harsh by far with the 1M pot. i suspect it would have been fine in the treble with 500k, but the bass of the VH2 was over powering in that guitar.
you are right - a pot can't add treble, but it takes less away. more treble can give the illusion of less bass. perhaps the warpig owner felt they were too dark in his guitar, and that with the 1M pots it helped things.
in the end i fitted pickups from another manufacturer in that V, but it was a tricky case. i expect stormy mondays would have worked, but wouldn't have been appropriate for my music.
i think 1M pots are good in the right situation, where things are say 20% too dark for you and you have 500k. based on my experience i would never wire a pickup straight to the jack, or with a no load pot. some people get good results - but not me. my amp is a Marshall 2204 - easily bright sounding, which might have affected my experience.
on some of my steinbergers, i've removed the tone control from the bridge pickup - this is a nice mod to brighten the tone a bit. its not quite the same as going to 1M pots, but it is similar. it might be a good way to see what 1m pots would give you if you installed them.