This amp is a Natural Music Guild CA-15 amplifier, similar to both the Bartell CA-10 and the Contessa CA-15 Mini Bass amplifiers.  It uses the same tube lineup as the CA-10: (2) 12AX7, (2) 6V6, and a 6CA4 with controls for SPEED, DEPTH, TONE, and VOLUME .  It uses a 12" speaker like the Contessa Mini Bass.  

 

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