I have a strat with a jb jr in the bridge and ssl 2 in the neck and middle. the thing is that I use my tone knobs alot, especially for distortion. Some times I find the jb jr abit too harsh and the way I usually solve this is by rolling down the tone knob a bit. Also when using single coils I usually turn the tone knob down at least half way too make the sound smooth rather than the thin sound you get when you just keep the tone knob at ten. Also I have the secon tone knob wired to the bridge pickup instead of the middle pickup.
However the problem with this guitar is that when i roll the tone knob down the pickups immediately lose charachter and sounds weak and dull. What would be the easiest why to fix this problem? I like the guitar but it is annoying when you don't get along with your beloved intsrument.
Try a different type and value of tone cap. They're cheap, you can get a bunch and see if any of them make a difference to you.

I'd suggest trying an Orange drop in a .015 and a .022 and a .047, though there are plenty of others to try. You can also get different volume/tone pots, but the stock Fender ones are OK so it might not help much.
I've put some high quality pots in it. I also have identical pots in other guitars so I don't think that's the problem. I'll try some other caps. The cap I have in it now (.047 PIO) from what I've heard is supposed to work well in a strat but perhaps it's not as good as everyone make it out to be. Could it be possible that the pickups don't like tone knobs? I know that the jb jr is mostly high mids and treble. Is it possible that might also be a reason it doesn't soud the way I want?
Also I have a very similar setup in another strat except for different pickups (handwound vintage style strat pickups). That setup works well in that guitar. I'm not sure that it's the same type of cap in that one but I know it is of the same value.
I bet that .047 is your problem. Try something smaller, I'd use a .022 or a .015 with a JB.
I'll try that. I just find it a bit wierd that the neck pickup which is a vintage style strat pickup acts the same way as single coils usually works well with .047. Anyway, thanks for the advice.