YAMAHA JX50B bass amplifier with five control knobs. - Brand: YAMAHA - Model Name: JX50B - Type: Bass Amplifier - Control Knobs: 5 control knobs This is an old vintage amplifier, but it still works without any problems. As expected from a manufacturer of audio subwoofers, it reproduces low B frequencies with a deep, resonant sound. Size is 30 x 59 x 67 cm (depth x width x height). Thank you for viewing. Weight is unknown.