Back at the dawn of audio-time, the American hi-fi industry took root in the post-World War II surplus of both electronic components and electronic technicians (as we wrote about in an
previous blog entry). We've mentioned how much the audio industry owes to those who gained technical proficiency from training received while in the armed forces, and today's subject also came out of that incredible pool of talent.
We've also mentioned how tightly-knit are the threads of the industry, how the same names appear again and again, designing a piece for a friend here, starting a new partnership there. David Hafler is one of those threads, inextricably linked to his own companies Acrosound, Dynaco and David Hafler, but also responsible for helping many more companies get their start.
According to Barry Willis' obituary of Hafler in
Stereophile, Hafler was born in 1919, had a degree in Math from the University of Pennsylvania and saw duty as a communications specialist in the Coast Guard during the war. As was true of many of his fellow techie servicemen, after discharge Hafler turned to electronics as a vocation.
As detailed in Greg Dunn's thorough and informative
Dynaco Company History, David Hafler and friend Herbert Keroes founded Acrosound in Philadelphia in 1950. The company wound transformers for individual sale as well as OEM usage, and Acrosound transformers were utilized by hobbyists and manufacturers alike.
Acrosound's presence and prestige were enhanced by the publication of articles by Hafler and Keroes in the Audio Engineering Society's journal, Audio Engineering (which later split from the AES and was renamed simply AUDIO). "An Ultra-Linear Amplifier" appeared in the November, 1951 issue, and helped popularize ultralinear amplifiers (and not coincidentally, the transformers Acrosound made for ultralinear applications). "Ultra-Linear Operation of the Williamson Amplifier" appeared in June of 1952, and presented an upgrade to the then-popular "
Williamson", design by D.T.N. Williamson of the M.O. Valve Company, and detailed in articles in the British journal "Wireless World" from 1947 through 1949.
In the early '50's, home-builders of amplifiers usually started from scratch, followed a schematic and parts-list, and had to purchase all the parts individually. Those companies which did offer kits still required the builder to stuff and solder the circuit boards; Hafler had the then-novel idea of offering complete kits for amplifiers featuring fully-assembled circuit-boards. Acrosound offered a
preamp kit which looked similar to our featured unit. Keroes apparently opposed getting into the kit business, and the rift between him and Hafler caused the partnership to dissolve in 1954.
Hafler forged a new partnership with Ed Laurent in 1955: The Dyna Company, commonly known as Dynaco. The new company was located in Philadelphia, and their first product, a 50-watt power amp designed by Laurent, appeared soon after their doors opened. That first product was called the Mk.II, even though there WAS no Mk. 1. Perhaps the idea was to give an impression of an established company, the same reason Porsche called their first model "356". Or perhaps Mk.1 did exist, but wasn't quite ready for prime time.
Not surprisingly, the Mk. II featured Dyna-built transformers, and was available in kit form as well as fully-assembled. The Dyna reputation for clarity in instruction manuals and ease of build began with the company's very first product. The Mk. II was quickly improved into the legendary Mk. III in 1957, and a companion preamp, the PAM-1 (PreAmp: Mono), appeared the same year. The preamp was powered by an octal socket on the Mk. III.
Dynaco entered the stereo era in 1959, with the introduction of the Stereo 70, a 35-watt per channel power amp. The Stereo 70 also featured an octal socket for powering the PAM-1, either singly or paired. The logical mate to the ST-70, our subject piece the PAS-2 (PreAmp:Stereo) appeared in 1960.
The Mk. III and the PAS-2 (and its successor, PAS-3) were among the best-selling pieces of audio gear of all time. Consider them the Model T and '32 Ford of the audio world; thousands were "hot-rodded", and indeed, entire companies were based upon modifying them.
We will continue with the story of the Mk. III and PAS-2/3, and how they influenced an industry. We will also examine the later Dyna products and the legacy of David Hafler and Dynaco alumni.
