This is a1960s SOUND ELECTRONICS Corp VINTAGE Bass X-202 Tube AMPLIFIER. Serial #21121 Made in Mineola, NY, USA. I’ve had this underrated amp for almost 25 years. It was in very sorry shape when I got it. The grey Tolex was a mess and the bottom of the case was beat up. I stripped it, filled the holes, and painted it flat ink blue with variegated gold leaf flames for a blues hot rod look to go with my playing blues standards. It would not cost you much to recover it with Tolex if you want the original look. It has the original exterior hardware and speaker cloth but I added a pair of rails to the bottom to keep it off the floor. The Jensen 15 speaker came from CAE in San Mateo, CA as the original was torn. I replaced some resistors, diodes and capacitors. The power cord is probably not original. All the controls appear original: On/Off, Bass, Treble, Volume, Polarity, plus 3 inputs and one external output. And the little blue power indicator works. And it has an internal fuse. I made the schematic of the amp circuitry that I will include. It weighs 42 pounds and is approximately 28x20x11. I read that Sound Amps were made in Mineola Long Island NY in the 1960s by John Dougherty, a former Ampeg employee, who later went on to run Marlboro amps, made by MICA (Musical Instrument Corporation of America) in Syosett. The Sound amps were made really well & used similar circuits to Ampeg & Oliver units. Dougherty also invented and patented the Quadra-Sound Blender, an outboard effect, which combined tremolo, vibrato and reverb, to produce a couple of unique surf-like effects.