The Hub: History of Dynaco part 1

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.
Audiogon bill,
Thanks for the trip down memory lane. My first experiences in audio were with the Stereo 70, modified of course, and I too received my electronic training courtesy of the taxpayers, in the military. It's exciting to think about pioneers in any discipline, but we have to thank people like Hafler, Keroes, et al, for their vision and hard work.
The greatness of the original Dynaco designs are proven by the fact that a great majority of their kits were assembled by first time builders and most of those kits worked when plugged in for the very first time. This becomes more amazing when one considers that other than their transformers, the chassis and the tubes (usually Telefunken), Dynaco used the cheapest parts they could find.

You wrote: Those companies which did offer kits still required the builder to stuff and solder the circuit boards...

Most companies that offered kits at the time didn't use circuit boards at all, they were assembled by using the "point to point" method. Dynaco did eventually sell kits that required the builder to assemble the circuit boards: The FM-1 and FM-3 (designed by the legendary Stuart Hegeman).
Khagen, Deci:

Thanks for the comments. Deci, you are of course correct in stating that most kits were point-to-point; sorry I didn't clarify that point. I think I may have mentally blocked out the horrors of many of those rat's-nest units!

We will eventually look into Hegeman's career, from HK to HAPI. Anybody remember that one?

Thanks for taking the time to write.
We will eventually look into Hegeman's career, from HK to HAPI. Anybody remember that one?
Yes! Although I've never seen one in person. Peter Aczel reviewed several incarnations of the HAPI preamp in "The Audio Critic" volume 1 nos. 5 & 6, and volume 2 nos. 1 and 2, ca. 1977-1979. I have the last three of those issues -- when you work on that article let me know if you'd like pdf's of the reviews (which were glowing).

Wonderful article on Dynaco, Bill. Thanks!

Best regards,
-- Al
The Dynaco ST70 was my first venture into the audio world.
I used a Pas2 and a pair of small JBL's. I later purchased a
second ST70 and completely rebuilt both units with upgraded
resisters and caps. I also used some silver wire. I wired them in triode and bridged them to use as monoblocks. My source was a Lynn LP12 table and My speakers were replaced with some Snell C's. This was many years ago but my buddies tell me that they still think it was the best sound they had heard in my house.
After having built a Heathkit amp and tuner, I built several Dynaco Mk IIIs, and they were easy. The PAM-1, though, was a maze of wires. I finished it, but it was a mess and produced more anxiety for me than any final exam.

Audiogon bill, I thoroughly enjoyed your informative post.

I recently sold the last of my Dynaco equipment which was a clean pair of Dynaco MKIII monos. Now that I sold them the price is sure to double in the near future.
Al, Tan, Db, Rrog, thanks for the kind comments.

Al, not sure an Aczel endorsement is a plus. Tan, ST70s have often outperformed pricier gear, as have the Snells. Db, for me, preamps are nearly always spilkies-inducing, whether it's building 'em or looking at someone else's labyrinthine wiring job. Rrog, there's enough of the MkIIIs out there that they're not going to go for Marantz 9 money anytime soon. I hope. ;->
I was once told by Art Ferris that the three top selling preamps of all time were 1) Marantz 7 2) Dynaco PAS (with at that time around 100 K units sold) and 3) Audible Illusions (at that time around 17 K sold). Now those number were a couple of years ago but the differences between the top two and third place are pretty staggering.
Thanks, Myles.

Wow, haven't heard Art's name in a while; this is the Art who used to be in Castro Valley? Sold him Mac pieces, back in the day.

One of the real frustrations of audio archaeology is that first-hand info is almost non-existent. It's hard to get a sense of scale regarding production quantities, but I'm sure the numbers produced by companies like Garrard, AR and Dyna would totally swamp almost anything being done today, at least outside of a few Chinese mega-factories.

Thanks for taking the time to write.
Nice article. One note, however. Regarding the existence of a Mark I power amplifier, according to an interview with David Hafler in Vacuum Tube Valley (issue #15) your second statement is the correct one: there WAS a Mark I but it was not "ready for prime time".

Hafler: "We had an amp that we called the Mark I, but it never went into production because it needed some modifications before it got too far. So that became the 50-watt Mark II."

Hope this is useful information.
Thanks, I appreciate that. If I'd had another month to research, I might have EVENTUALLY come up with that!

Thanks for the info, and for taking the time to write.
Yet again, another stellar thread. Thank you!!!

David Hafler may have been Bud Fried's best friend. Bud took David's passing especially hard. And, like so many other real life relationships, when one of them is taken from us, the second goes not long after.

Bud used to often talk to me about he and David using a pair of David's KT88 monoblocks as a measuring stick way back when. I didn't realize it until recently, but the Dyna MKIII were most likely what he was referring to.

A couple of years ago, I put together a Dynakit ST70. For whatever reason (modern resistors, caps, and diodes?), despite all of the reference level amplifiers I owned/own, not one of them equal the ST70's midrange and overall rightness of tone.
Wow. I read all of Fried's newsletters through the years, spoke with him a few times, and never heard of the connection to Hafler. Both were, of course, in Philadelphia for many years, and it's certainly a logical association.

Thanks for the info. I'm a great fan of Fried's, and am always glad to learn more about him and his career.
Hi Bill,

Not sure about Art being the one in Castro Valley. I know him from Pleasanton, CA (So of SF) and of course is the owner of Audible Illusions.

Maybe the two Arts are one and the same. Somehow I've never encountered
EITHER one in the flesh. ;->

Thanks, Myles.
Same guy. Take a look at this review of an Audible Illusions pre:
Awesome - love reading this having just recently purchased a Dynaco ST-70 from Mr. Will Vincent. Excellent article!