I'm trying to buy an Epiphone Viola Bass (the Hofner Beatle Bass imitation). But the pitch on the Epi Viola basses I've tried drifts considerably when I play the open E (or low notes up to about G at 3rd position), oscillating between flat, sharp, on pitch, sharp, flat, etc, a bit like tape warble. (This happens regardless of right hand technique.) Other than this, I like the bass, though I'm not interested in it if the problem is unfixable. Is there a way to cure this pitch warble problem or should I move on to another bass?
Check two things: -That the pickups are not too close to the strings, and -That the strings are winded correctly and there is a good breaking angle after the nut, going to the bottom of the tuning peg. The strings should depart from the botton of the tuning peg, not the middle or top. Lack of angle at the nut can sometimes create such warbling effects, in my experience.
I have the Epi, and love it... I do not seem to have that problem, so check the strings and pickups stuff as mentioned before... Does not seem to be inherent in the instrument...