This is getting on my nerves, help?

[StarscreamG1]

As I have commented before, my first bass had NO setup and was a pure torture device to learn to play on. I didn't know any better so thats what I learned to play on. Picking it back up a few months ago and now knowing about setups etc. my basses now have decent set ups (though could be better but Im on that)....

Anyway, because I had to literally fight the fretboard on my first bass (and had no idea it was wrong at the time) its left me with a pressure/tense type habit with my left hand. I don't think I 'squeeze' the notes (I have always been complimented on how I sound on a bass for what its worth) but I hit them hard and firm. I never seem to be working with the neck (even on my precious Fender P and Dyna) but attacking it?? But I don't /look/ like I'm attacking it (if that makes any sense)

I now have a problem...on some things I play I end up with a horrible cramp on the underside of my thumb where it touches the back of the neck. Its like blinding white pain/ache and I end up having to stop and shake the hand and wait a few seconds.

I don't seem to do this with all my stuff though and I don't get it. I have tried to analyze what riffs bring this on and what ones dont and it seems to be real close together notes and 'interesting' fret/string changes. Sometimes switching basses to a smaller neck radius helps but earlier tonight nothing I switched over to helped. *my hand is still achy around the thumb from earlier*.

I have tried to be conscious of the amount of pressure I have with that hand/how Im gripping the neck because the axes I have now you don't have to 'fight', and I can relax it for a run through once or twice and then I just feel my hand tighten up. My thumb position on the neck is more classical style (I have no idea where I got that from as I was self taught but from reading around here that seems to be the preferred method for holding the neck??) held at the center of the back of the neck. I dont put a choke hold on the neck so it can't be how Im gripping the neck.

Is there something I'm missing or what? ... help?

[lemur821]

How does playing without your thumb on the neck turn out? Still pain? You must be unconsciously squeezing (or pinching) the neck some of the time in order to get a cramp.

[StarscreamG1]

I'm sure I'm squeezing the neck and I can't figure out how to stop. And I know its because of how HARD I had to fight the neck on my first bass. Its the only way Ive ever known how to play (and good axes this time around have shown me I've got some bad habits to try and fix). I have not tried to play without my thumb on the neck but I am sitting here with my Dyna in my lap and I tried it after reading your comment. I found I was putting a lot more pressure with the fingers on the strings but the thumb didn't ache at all. ... just practiced some more like that (thumb not on neck) with the one piece that is giving me so much trouble (an original riff) and no pain. I paid attention to the pressure I was using with my fingers a bit and after a few times I was able to get some serious speed up with no thumb on the neck.

Is that an actual way to hold the neck? If so I have never heard of it before....