Vintage EV Electro-Voice Model A20CL Lowboy Circlotron 20W Tube Amplifier PARTS
Monday, November 9th, 2026







It is 100% original, in untouched and unmodified condition. This is a mono integrated amplifier with phono equalization settings and the well regarded Wiggins Circlotron circuit. Made in the mid to late 1950s. Rated at 20watts between 20 and 20KHz within 1dB. According to the sales brochure, all DC is removed from the output transformer allowing class B operation of the output tubes. All switching transients are eliminated resulting in the efficient utilization of the output tubes. The impedance of the output transformer is one quarter of that found in conventional amplifier circuits, affording vastly extended range response at full rated power. A damping factor control permits the particular loudspeaker system employed to be perfectly coupled to the amplifier output, eliminating loss of bass from over-damping, or override due to under-damping. This unit has been in my possession for a few years now, but the project pile has gotten out of control and I decided I need to start thinning it. I never even powered this one up (while I’m no expert in tube equipment, I know better than to power up an old unit that has been dormant for as long as this one seems to have been). All tubes seem to be present, as well as all original knobs. Cosmetically, the unit in good to excellent condition (considering its age), with some stains here and there. Please inspect pictures carefully as they are part of the description. The amplifier will be double boxed and surrounded in foam to ensure safe arrival to its destination.