A guitar bass tends to be easier to play than an upright because the strings are not as taut. Has to do with the physics of pitch and string length.

A fretless requires increased accuracy in machining the fingerboard to the required tolerances. Frets can be adjusted to make up for such deficiencies. A fretless fingerboard has to be right on its own. Given that the fingerboard is accurate, the neck is adjusted properly, and the string gauge is properly matched to the instrument, there should be no problem with buzzing or rattling. You do want to hear that hornlike "mwah" sound which gives the fretless souind some of its unique character. You should be able to hear this with or without an amp.

Dean Guitars has an electric upright which retails for $500 USD. It sounds decent, though cannot be played with a bow.

Hope this helps. Good luck in your efforts.

R.

"My primary musical instrument is the personal computer."