This amp is a Contessa CA-15 Mini Bass amplifier, similar to both the Bartell CA-10 and the Natural Music Guild CA-15 guitar amplifier.  It uses the same tube lineup as the CA-10: (2) 12AX7 (7025), (2) 6V6, but with a solid-state rectifier with controls for Bass, Treble, and Volume.  Interestingly, it uses a 12″ speaker for a bass amplifier. Schematic available in the SCHEMATICS section.