This is your typical tube PA head that was very common in the 60’s. This one uses (4) 12AX7 and (2) 6L6 tubes. It has 4 channels, each with it’s own Volume control, along with a master Volume, Treble, and Bass controls. It also features reverb controllable with a single knob for the entire unit. No labels indicating Bartell manufacture but it certainly looks like one.
Cool ! I bought one of these heads at the pawnshop across the street from Ted’s old music store about 8 years ago. It was labeled “Hohner”, but it sure looked like a Ray Massie buold.
Steve Soest