What may have helped kill Dynaco tube gear in the 1970's ?

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What may have helped kill Dynaco tube gear in the 1970's ?

Postby Bob01605 » Wed Apr 02, 2008 2:40 pm

Image

Most tube lovers feel that the solid state revolution was the primary force in the demise of tube audio. Although that was probably the primary factor involved another issue that gets little attention is the FTC's 1974 ruling on how amplifier power may be advertised. What happened was in response to manufacturers rating amplifier output by a wide variety of methods - ("music power"', "peak power", "rms power", "continuous power" etc.), in 1974 the FTC came out with their guidelines as to how amplifiers must be rated.

As you can see above in the 1975 Dynaco product brochure some of the Dynaco tube gear did not fare so well. The venerable ST-70 which had been advertised at "35 watts per channel" and "20 cps to 20 kc within 1 db of 35 watts at less than 1% distortion" was now rated at just 20 WPC and a power bandwidth of "50 - 10,000 Hz"

Many prospective and present customers probably read into this that "Hey - only 20 WPC and 50-10,000 Hz bandwidth?? - Dynaco has been lying to us for years!" Of course this is not the case but prospective customers looked at these specs and some probably didn't buy the amp because "It won't reproduce ALL the music" (20-20,000 Hz)

Yes - tube amps slowly went away and were replaced by hard sounding solid state amps that had none of the musical magic of the tube gear. How many of you, maybe 50 years old or older, traded in your Dynaco tube gear in the 1970's for "better" solid state gear ? LOL - I did (foolishly) and I'm still kicking myself in the butt for doing so ...

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Postby Kyle K » Wed Apr 02, 2008 3:37 pm

IIRC, in an interview with the now pretty much defunct Vacuum Tube Valley, David Hafler, when asked about why Dynaco entered the solid-state market said that SS gear sounded the same as tube gear. I was shocked that he actually said that. If the head of the company thinks that, you would think it would certainly influence marketing decisions.
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Postby EWBrown » Thu Apr 03, 2008 6:08 am

Dynaco was also trying to enter the SS amp market big time, and I'm sure that they considered tubes as "obsolete" and "less desirable" simply to sell their new products. Plus they were pushing the Big Watts, and the relatively "flea powered" stuff was too old fashioned to the sales and marketing folks. THen there were those notoriously ineffecient speakers like AR-2s, AR-3s, AR-4s, etc. They were dull enough, in sonic quality to hide the "sins of solid state" back then...

I still have one of the original Dynaco ST80 SS amps, and it sounds awful, when compared to an ST-35, SCA-35 or ST-70. The ST80 can make good speakers sound bad, and with lesser speakers it sounded, well, OK. Yellow_Light_Colorz_PDT_20

I keep it around just to demonsstrate to the "transistorized true believers" that the 60s and 70s era "sand amps" weren't really so great, after all...

/ed B in NH
Last edited by EWBrown on Thu Apr 03, 2008 8:10 am, edited 1 time in total.
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Postby Slartibartfast » Thu Apr 03, 2008 6:37 am

Kyle K wrote:IIRC, in an interview with the now pretty much defunct Vacuum Tube Valley, David Hafler, when asked about why Dynaco entered the solid-state market said that SS gear sounded the same as tube gear. I was shocked that he actually said that. If the head of the company thinks that, you would think it would certainly influence marketing decisions.


I am curious. Why is Vacuum Tube Valley defunct?

Thanks

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Postby Bob01605 » Thu Apr 03, 2008 7:23 am

EWBrown wrote:Dynaco was also trying to enter the SS amp market big time, and I'm sure that they considered tubes as "obsolete" and "less desirable" simply to sell their new products. Plus they were pushing the Big Watts, and the relatively "flea powered" stuff was too old fashioned to the sales and marketing folks. THen there were those notoriously inefecient speakers like AR-2s, AR-3s, AR-4s, etc. They were dull enough in sonic quality to hid the "sins of solid state" back then...

I still have one of the original Dynaco ST80 SS amps, and it sounds awful, when compared to an ST-35, SCA-35 or ST-70. The ST80 can make good speakers sound bad, and with lesser speakers it sounded, well, OK. Yellow_Light_Colorz_PDT_20

I keep it around just to demonsstrate to the "transistorized true believers" that the 60s and 70s era "sand amps" weren't really so great, after all...

/ed B in NH


Ed,

Years ago I had a Dynaco ST-120 which I believe was the original Dynaco sand amp released about 1966. I think this amp would give your ST-80 a run for the money as the worst sounding Dynaco amp ever created. I remember years ago running this amp through my old PAS-3X preamp. Even that mellow (and a little hazy sounding) preamp could not hide the sins of early solid state design pumped out by the ST-120. The ST-120 was a hard and very dry sounding amp that introduced listener fatigue after just a few minutes of play.

I agree with your assesment that those early speakers hid some of the sins of those early solid state designs. I also had AR and KLH speakers in those days and even with the tweeter controls turned up the top end was dull enough to hide some of sonic issues that those early transistor designs had. I think the AR speakers were even worse than the KLH designs in this regard. I can still remember a friend of mine adding a German made tweeter on the top of his AR3a to try and get some top end out of his speaker.

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Sand Fleas and other Nasties

Postby EWBrown » Thu Apr 03, 2008 8:23 am

THose old ST-80 and ST-70s were in the days before complementary pair transistors, and bipolar power supplies, so the audio output had to be coupled through a big fat electrolytic capacitor, which alone destroys the sound quality. Then they also used to insert an inductor in series with the output, in the ST-80 this was wound around the body of the big (beer can sized) caps, which was really beyond the definition of "crude" design at its worst... :o :o :o ( is there an upchuck smiley? )

The "end" was when McIntosh went SS and even used fancy and very expensive OPTs to match things up... At least they weren't pumping audio through a nasty "computer grade" capacitor with a coil wrapped around its midsection, , so they were at least a level or two better, but at the exhorbitant prices, they better darn well have been...

My first SS amp, actually a full receiver, was a Sansui 5000X that I bought at the PX in Long Binh, in Viet Nam, in mid-1971. The going PACEX price was $179.95, and the US equivalent, 5000A was just below $600. Back then, I thought it sounded OK, but then I was running it through some kinda crappy speakers, and somehow the combination of two "wrongs" somehow made a "right". (almost...)

Years later, when I connected it to a set of Altecs, they sounded so very bad, I assumed that the speakers were at fault, but that was later disproven, once they met up with an ST-70...

The 5000X was also notorious for blowing its output transistors (at least they used a bipolar PSU and no computer grade coupling cap) and after the third replacement of them, even with better transistors, and most of the rest of the PA stage transistors (they went like a string of firecrackers), I finally gutted out the power amp section and just used it as a tuner / preamp until it completely died. It eventually landed in the freebie pile at the local Hamfest, long ago... Someone rescued it, just for the wooden case Yellow_Light_Colorz_PDT_07

/ed B in NH
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Re: Sand Fleas and other Nasties

Postby Slartibartfast » Thu Apr 03, 2008 8:53 am

EWBrown wrote:THose old ST-80 and ST-70s were in the days before complementary pair transistors, and bipolar power supplies, so the audio output had to be coupled through a big fat electrolytic capacitor, which alone destroys the sound quality. Then they also used to insert an inductor in series with the output, in the ST-80 this was wound around the body of the big (beer can sized) caps, which was really beyond the definition of "crude" design at its worst... :o :o :o ( is there an upchuck smiley? )




Ed,

You mean like this Dynaco SCA-80Q:


Image

This looks like the audio output is fed through an LC network, through the headphone jack and then out to the speaker terminals.

Also, if you look at the rectum frier board, you will see some very hot power resistors. :o
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Postby Kyle K » Thu Apr 03, 2008 10:52 am

About Vacuum Tube Valley - The company still exists as a seller of tubes, parts and gear, and they still sell back issues. The last issue of the magazine was in 2004, although I think they were taking subscriptions well after that.
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Postby soundmasterg » Thu Apr 03, 2008 2:28 pm

Yes, I renewed my subscription and have not received anything. I've asked for my money back several times only to be told that they are working on a new issue and they will have it ready before the end of the year....that was 2007.

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Postby EWBrown » Tue Apr 08, 2008 8:02 am

That ST-80Q looks the very same, inside... I did end up replacing the output transistors and some smaller caps, but it is otherwise pretty much "stock", with no mods or "serious" repairs.

I suppose with that era's lousy SS amps, feeding a pair of AR-3s, and "headbanging" with Deep Purple, Led Zepp or Jimi Hendrix, that some rough-sounding amps into muddy-sounding speakers didn't really matter all that much (and if any "spiritual condiments or adult beverages were part of teh experience, then moreso was the case of two wrongs somehow appearing to make a right) Yellow_Light_Colorz_PDT_09 Yellow_Light_Colorz_PDT_04

Oh, yeah, don't forget the couple of quarters taped to the top of the cartridge head on thoose ubiquitous Garrard record-changers :o

Those groove-grinders tracked about as well as an Irqaui Scud missile...

/ed B
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