Dynaco

Founded by David Hafler and Ed Laurent in Philadelphia, Pennsylvania in 1955, Dynaco was an American hi-fi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components.

David Hafler and his friend Herb Keroes started a Philadelphia, PA based company called Acrosound in 1950, dedicated to building and selling audio-quality output transformers. Herb's mother invested a substantial amount of money in the company, which apparently didn't return much of a profit. As part of the marketing of the transformers, and concurrent with Hafler's own interests in audio, they developed and extended the Blumlein "Ultralinear" circuit, using taps from the output transformer to feed signal back into the output stage screen grid circuitry. Numerous homebrew as well as commercial hi-fi amplifiers from the early '50s were based on Acrosound transformers. Hafler was interested in selling entire amplifiers as build-it-yourself kits, a somewhat novel approach in the early '50s. The average hi-fi enthusiast generally started with a schematic, chose an output transformer (which determined the power of the final amplifier), selected parts and tubes accordingly, then hand-crafted his unique component on a homemade chassis. Further, Hafler's idea was to supply preassembled, tested circuit boards which only needed to be connected to the transformers, controls and power supply to produce a working unit. Even the Heath and Knight units of their day generally required the purchaser to assemble and test the PC boards themselves, a time-consuming task.

In 1954 Herb and Dave went their separate ways (allegedly due to differences of opinion over kit production and marketing). During a visit to the New York-based Brociner Electronics (owned by Victor Brociner, whose influence in audio design was also far-reaching) Hafler met up with Ed Laurent who had designed a novel single-tube driver circuit for a power amplifier. More or less together, they founded the Dyna Company with the intention of not only producing transformers, but high-quality audio circuitry using them. Soon after incorporation in October 1955 at 617 N. 41st St in Philadelphia, Dynaco announced the Mk. II 50-watt amplifier. Available as a kit or preassembled, it sold for several years, into the 1960s, superseded only by the soon-to-be-classic Mk. III 60-watt unit. Hafler wrote an article for Radio-Electronics Magazine in 1955 delineating the design of a high-power version of the "Williamson" amplifier using Ultralinear circuitry and the new output transformers. This amplifier offered a slightly different circuit topology from the Mk. II and Mk. III units soon to appear in Dynaco's line, but showed that the Ultralinear idea was applicable to many amplifiers. Shortly thereafter, Dynaco moved to 3912 Powelton Ave., where they remained for several years. Interestingly, the building was the former site of a chocolate factory, and the old walk-in refrigerator served as a well-isolated listening room!

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