The Hub: History of Dynaco part 3

In Part 2 of our Dynaco history, we left off with the influence and reach of Dyna's tube gear, still widely used today. Our focus in this entry is the solid-state era at Dynaco, and how the people and products of that era continue to influence the audio industry.

Dynaco was a late arrival to the solid-state show, which, given the general horribleness of many early solid-state amps, was probably a good thing. Greg Dunn's invaluable Dynaco History website tells us that Dyna's first transistor amp, the Stereo 120, appeared in 1966. By 1966 standards, the Stereo 120's 60 real watts per channel marked it as a high-power amp. As a side note, the FTC RMS power-measurement standards were not in effect then, and amps were often rated by standards such as "IHF peak power" or "instantaneous peak power", often referred to as "what it puts out right before it bursts into flames". By all accounts, Dyna's rating was a real, conservative one, as was expected of them.

The PAT-4 (PreAmplifier, Transistorized) appeared in 1967 as a companion piece to the Stereo 120. The PAT-4 was well-reviewed by Stereophile (although that review is unfortunately not yet in their online archives), but years later, in a Stereophile interview with Steven Stone, J. Gordon Holt expressed regrets about the over-the-top nature of that review. "It was several weeks later that I started hearing that it was doing other things less well than the tube stuff I had," Holt said.

Seeking to broaden their product range, Dynaco introduced the A-25 speaker system in 1969, at $79.95 each. Just to give a bit of perspective, that $160 per pair is equivalent to $925 today; so while they were an amazing value, the A-25s were NOT throw-away cheap. The A-25 became a favorite of music-lovers seeking neutrality and excellent overall performance. You can still find used specimens on AudiogoN for $200 or less (such as this pair) and they still provide incredible bang for the buck.

The A-25s were designed and built by the Norwegian-Danish company SEAS, and according to Dunn's Dynaco speaker history, over 1,000,000 A-25s were produced over their long run. The range was extended to include the A-10s below the A-25s, and the A-40s and A-50s above them. All were based on an "aperiodic" (internally vented to a sub-enclosure) configuration, and varied primarily in size, bass abilities, and power-handling. The A-25 was perhaps the best-balanced of the lot, and sales reflected that.

Dyna introduced a stream of new electronics, as well (see complete line-up in the AudiogoN Bluebook). A lower-powered variant of the Stereo-120, the Stereo-80, was introduced in 1969, along with the SCA-80, an integrated amp which featured a simplified PAT-4 and Stereo-80 on one chassis. A later variant, the SCA-80Q, included Hafler's "Dynaquad" circuitry, which synthesized rear-channel ambience for a rear pair of speakers. While not true quadraphonic sound, Dynaquad was popular, and was offered in the outboard QD-1 "Quadaptor", as well. The product lineup was completed by the FM-5 and AF-6 tuners, which were in the true Dyna tradition of offering remarkable performance for reasonable cost.

In 1970, the Phase Linear 700 introduced the era of super-power amps; its 350 watts per channel had previously only been seen in industrial amps like the McIntosh MC-350 and MC-3500. The 700 was rave-reviewed by Stereo Review's Julian Hirsch, likely because Hirsch's reference speakers, the AR-3a, were notoriously inefficient. At any rate, the horsepower race was on in the audio world, despite landfills full of blown speakers and burned-up amps.

Dynaco followed suit in 1972 with the Stereo 400, at least partially designed by James Bongiorno, who soon became better-known for Ampzilla, and started the Great American Sound (GAS) Company to build it. The Stereo 400 became a favorite of tweakers, and a double-the-output-transistors mod by Frank Van Alstine became an underground superstar at a relatively low price. Dyna followed suit with the Stereo 416, a to-the-max version of the 400.

The 400/416 was Dynaco's last hurrah. Founder David Hafler left in 1974 to work with Ortofon, having sold Dynaco to conglomerate Tyco, in 1969. Hafler founded the Hafler Company, which for many years produced high-value components reminiscent of vintage Dyna. Dynaco passed through a number of hands, including speaker company ESS, Stereo Cost Cutters (which became Sound Values, Inc.), and the Panor Corporation. As is the case of many other great American brands like AR, Fisher and Scott, the end came not with a bang, but a whimper.

Today, the sales-volume of Dynaco products is seen in the audio world only in the likes of iPods, where over 250 million units have been sold. Clearly, there is still a market for products for non-audiophile music -lovers. If only the audio industry would awaken to that fact.
Well done Bill, brought back a flood or memories, good, bad and downright ugly. Many thanks for these informative postings.
Thanks for taking the time to send your kind comments. I appreciate it.

So-- what kind of Ferrari do we have in the garage? Or is it a purely platonic relationship? ;->

My all-time faves were the 330 GTC and 365GTB-4.
My first and last was a 250GT SWB. Should have kept that baby worth a ton of loot today. Paid $2,500.00 for it in 1964, it was two years old then. Had a blast with it for about three years. Yep the 365 GTB-4 was fabulous aka Daytona, nearly bought one, but that is a lot of Ferrari.
Funny, I got a 250GT about that same time; unfortunately, mine was a Matchbox car!

The 250 GT was a beautiful car, and far more appealing to me than today's Ferraris. --Good thing, 'cause I could never afford one!
Drove a friends Testarossa about 3 weeks ago. Soon learned that a greybeard and a Ferrari is not a good match. Forgot how things happen so quickly in a Ferrari, my reflexes at 67 now can't keep up with what it takes to own one now. But at least have good memories of the one I had and it was marvelous. Nothing sounds like a V12 a full song. High end audio pales in that comparison.
....Time it was, and what a time it was, it was
A time of innocence, a time of confidences
Long ago, it must be, I have a photograph
Preserve your memories, they're all that's left you

And a pair of A-25s still working perfectly.

The greed of audio industry forced music lovers to walk away. Hopefully, the greed of today's manufacturers of $500 throw away items will lure music lovers back.

What is needed is NEW audio industry, offering awesome products for fair prices, like Dynaco and Hafler did.
Well, you guys left out a few things and need a minor correction. Regarding the speakers, the A-25 did not vent internally; there is a horizontal vent at the bottom of the front panel. The A-50 was divided into two chambers and was internally vented. I don't know about the others. Supposedly, each A-25 was "stuffed" while the assembler was looking at something that measured the "back EMF" from the speaker. The idea was to minimize that value. In more modern terms, the impedence peak characteristic of all speakers was reduced. In yet another fit of misplaced zeal, JGH gooshed over the A-25, claiming that its bass went lower than the AR 3a -- the gold standard of the time -- claiming that the A-25 was "flat to 30 hz." The statement is utter nonesense. The A-25 doesn't have anything below 50 Hz. That said, it is a much better sounding speaker than the AR-3a, which, despite its superior performance at the frequency extremes, has a rather discontinuous sound. The A-25 is a great example of the design principle of "get the midrange right and the rest will take care of itself."

Among the tube classics produced by Dyna was the FM-3 vacuum tube stereo tuner. Using the "tuning eye" tube, the home builder could align and adjust the tuner to meet it's specs without a signal generator or a 'scope. The FM-3 wasn't the most sensitive tuner out there, but featured a very steep quieting curve, so in the typical urban or suburban environment, it was very quiet. Of course, it had the classic "tube sound" of soft bass and gentle highs . . . but it was very musical, like the rest of Dyna's tube gear.

Contemporary tests of the time showed that the Stereo 120 did meet its specs, in compliance with what would become the FTC standard (other than the 1/3 power thermal-stress preconditioning period). It had a fully regulated power supply. The Stereo 80 had an unregulated supply, so it would equal the stereo 120 on transients, but had a lower continuous power. Oddly, and perhaps because of the difference in power supply, the Stereo 80 sounded better.

Julian Hirsch's gaga review of the Phase Linear 700 was not based the AR-3a, but on AR's "LST" which used the same woofer as the 3a but multiple midrange and tweeters from the 3a on a faceted cabinet. It was even more inefficient than the 3a, but unlike with the 3a, the non-ferrofluid cooled tweeters and dome midranges would not blow up under higher power. Hirsch's comment at the end of the review (having discovered the virtues of avoiding the dynamic compression inherent in driving such an inefficent speaker with a modestly powered amp) was "I wonder if 700 watts is enough?!!"
Bob: whould've thought we'd reach the point where $500 constituted "throw-away" territory? Clearly, I'm gettin' old.

Bruce: I recall Hirsch's comment, and given those speakers, he probably could've used another kilowatt or two.

You are of course correct about the A-25's vent; late-night writing sometimes makes for stupid mistakes. Likewise, the LSTs: afraid my decades of Stereo Review copies disappeared a decade again. My bad.

Thanks for taking the time to comment,guys!
thanks again for a great series Mr Bill

Bruce: were the ST80 and ST120 basically the same amp with different power supplies? If true, it's not all that surprising to me the 80 sounded better, albeit a lower RMS power rating. I've always asserted that the output stage power supply should have as low impedance as possible, and that "enhancement" (via regulation) only serves to raise the supplies' output impedance, thus degrading the amp's sonic signature.
I've been playing with Dynacos since I first got into this hobby - having started with the venerable Dynaco 70. I've owned 'em all except for the Mark VI... tons of fun to modify and a great way to learn circuits.

As I type this, I'm listening to a refurbished Dynaco ST-80 being driven by a modified Dynaco PAT-4. State of the art? Hardly, but it still sounds better than I imagined they would! A nice system for the family to play with while I get the expensive toys - heh.
Bob_b, Divide, thanks for the nice comments.

We all know that domestic tranquility brought about by deception is a
primary symptom of Audiophilia Nervosa! Good luck with that!
Thank you for this series. I used to build these kits with my father. Reading your series brought him back to life for me. Thank you.
You're welcome. Always glad to trigger good memories!