[quote name='Greggo' timestamp='1366037223' post='2047547']
to be honest I do do that, i use the floating thumb where my thumb is on string below one im plucking, but as im plucking my finger is hitting the muted string and this seems to create the sound. its not always noticeable, but its certainly there and is not something I've recalled when playing previous basses. I guess its partly technique but Im thinking there must be something else thats making it worse / more noticeable and was thinking that it may be my technique of stringing perhaps.
The action is on the low side (as low as can go without fret buzz), but then when increasing action it does lower the noise a bit, but then makes the bass harder to play.
The strings are Ernie Ball Cobalts on one bass and D'Addario EXL160's on the other. More noticeable on Cobalts with a pretty hot humbucker.
[/quote]
Oh ok then.
Is it more like a clicking sound? If so, maybe you push the lower string accidentally to touch the frets.
It might be your best option to observe closely what you are doing, and where the strange sound comes from....