If you prefer your sound a bit dirtier, or perhaps, looser, the premium price of a JBL equipped black twin might not be worth it. For some sounds it was a perfect, like stepping back through time to a Memphis recording studio. I sold it because, for me, it did not sound good. It was a late 68 production with gray framed JBL D120F's in it and the factory JBL badge on the grille cloth. JBL's are universally considered 'hi-fi'.very clean, good bass but perhaps a bit harsh on the treble side.brittle maybe? I had a factory JBL equipped twin for a very short time. Another clue on a later 60's speaker might be a tiny F punched into the foil label. Unfortunately these stamps are not always on the speakers and are sometimes on the cabinet, or on the inside or outside of the chassis. Supposedly, if they are original to that amp, they would have an ink stamp on them that matches the stamp on the tube chart inside the cabinet.or a stamp that would be a code like AA2565.25th week of 1965. Hi Scott, It is kind of rare to find factory installed JBL 120F's in a twin but not unheard of.
