While the two are often credited for creating the “Ultralinear” transformer, their work was an expansion of a circuit design by Alan Blumlein that never came to fruition. The secret to Blumlein’s clever design was to use taps from the output transformer to feed signal back into the output stage circuitry. The Acrosound transformer circuit quickly became a staple in the early 1950s for electronic hobbyists building their own amplifiers.

Following the success of their transformers, David Hafler began selling entire amplifiers as build-it-yourself kits—a rather novel idea for the time. This allowed the average audio enthusiast to follow a schematic, choose the power of their output transformer, select specific tubes and customize their own unique amp. What made Hafler’s idea different than the rest at the time was that his circuit boards came preassembled, freeing up a considerable amount of time for the purchaser. Allegedly due to differences of opinion over kit production, David and Herb went their separate ways in 1954.

During a visit to Brociner Electronics in New York, Hafler met Ed Laurent who was also designing power amplifiers at the time; they joined forces in 1955 as Dyna Company. Soon after incorporation, Dynaco announced the Mk. II 50-watt amplifier that came available as either a kit or preassembled. This sold for many years, superseded only by the soon-to-be-classic Mk, III 60-watt unit. As they gained momentum in the emerging hi-fi market, Dynaco relocated to a former chocolate factory with an old walk-in refrigerator that served as a well-isolated listening room.

Demand for Mk. II, Mk. III and PAM-1 preamp allowed the company to offer some new products: most notably the Dynaco Stereo 70. With the help of Bob Tucker, the ST-70 was designed in 1959 to reduce distortion and improve audio quality with four EL34 output tubes, a GZ34 rectifier tube, two 7199 input driver tubes, two ultralinear output transformers and a power transformer. At the time, solid-state amps were dominating the market and the ST-70 was available at a surprisingly affordable price. More than 350,000 ST-70 amplifiers had been sold when production finally ceased, making the ST 70 the most popular tube power amplifier ever made.

In the following years with Ed Laurent as Chief Engineer, Dynaco produced a multitude of hi-fi products including the FM-1 stereo tuner, the A-25 bookshelf loudspeakers, a range of solid-state amps and the Dynaquad integrated system matrix to create “4-dimensional” sound from stereo recordings. In the late 1970s, Dynaco released a short-lived set of new loudspeakers developed by Ed Laurent, the Phase III. The speakers were well regarded by the audiophile community, but their introduction was apparently too late to make any strong impression in the marketplace, and Ed Laurent left shortly afterward to join SEAS Corporation. Dynaco was acquired by ESS Labs, LLC in 1979, and its assets acquired by Stereo Cost Cutters. The Dynaco division was closed in 1980.

SCA 80Q Integrated Amplifier

The Dynaco SCA-80Q is an all silicon solid state stereo control amplifier of exceptionally high quality. It functions as the control centre for all mono or stereo signal sources, such as a record player, radio tuner, tape recorder, television sound, etc., and provides output connections from two 30 watt power amplifiers for either two or four loudspeakers, as well as a front panel jack for stereo headphones. Thoughtful planning has provided exceptional flexibility with remarkable ease of operation. The SCA-80Q incorporates special circuitry which enables Dynaquad 4-dimensional playback for increased realism from a four speaker system without any additional electronics. Alternatively it may be used as a conventional two channel stereo amplifier with provision for optional connection of a second pair of speakers in a remote location.

AF6 Stereo Tuner

The Dynaco AF-6 is the culmination of years of Dynaco design research directed towards the goal of exemplary performance under a wide range of reception conditions, the high reproducibility which assures consistent results from kit-built units, all at modest cost. It provides a generous layout for easy assembly and outstanding serviceability. The primary consideration in the development of each new Dynaco product is exceptional performance; the AF-6 delivers this in full measure.