In 1950, David Hafler and Herb Keroes started Acrosound in Philadelphia, a company dedicated to building and selling audio-quality output transformers. These transformers were well received in the marketplace, and their unique ‘ultralinear’ circuit design was used as a template for many homebrew and commercial hi-fi amplifiers. Hafler’s interest in amplifiers and kit sets led to a parting of ways with Hafler teaming up with Ed Laurent and founding the Dyna Company in 1955.

Keroes remained at Acrosound, continuing with transformer production and eventually following Hafler's lead, producing a few high-quality amplifier kits.

The 20-20 was a dual channel 18-watt power amplifier designed to match Acrosound's S1001 stereo preamplifier. The two channels could be operated in parallel to produce 36 watts mono. Controls included mono/stereo switch and two channel level controls.

The 20-20 employed a patented self-balancing direct coupled circuit combined with ultra-linear connected output tubes and Class A operation was used throughout. Silicon rectifiers were used in the power supply.

Originally priced at $69.50 (in kit form), today a well-presented or restored and working example would fetch around $650.00.

Click on a thumbnail
for enlargement