Bach says 24 frets and at least 5 strings. Gamba repertoire and all. But I only play that stuff around the house. On a 50s gig, 4 strings and 12 frets would be enough -- although I do like grabbing that low C on the last note of Sea of Love. Who cares if it's authentic. Norteño's not supposed to have a low B either, but it does now.