September 12, 2023
#470
Gentle reader,
Bob Berne, of Mesa, Arizona has acquired a number of rare original Dynaco stereo equipment over many years of searching. He, along with Bruce Woodrow, both readers of this blog, and I have become real-life friends.
Recently, Bob was able to win an eBay auction for a super-rare 1990's (Panor-era) Dynaco ST-400 Series II power amplifier.
As you may know, I have a Panor-era ST-200 power amplifier, matching PAT-6 Preamplifier/Tuner and QD-2 five channel update of the 1970's Dynaquad. All were purchased used via eBay over several years.
While the ST-400 Series II power amplifier has twice the power output of my ST-200, that means ONLY a 3 decibel increase in sound output! 3 decibels is the smallest increase or decrease in sound levels which most people can detect. For each 3dB increase in audio output, a DOUBLING of power output is needed.
The twelve photos above are the seller's which he used to post this super-clean and ultra-rare Dynaco ST-400 Series II power amplifier on eBay.
Bob, who has forgotten more than I ever knew about electronics and audio equipment in particular has provided me the following photos of the insides of his Dynaco ST-400 Series II power amplifier.
With the top cover removed, one can see the interior is dominated by the large toroidal power transformer and two huge power capacitors. The front of the amp is at the bottom of the photo.
Both sides have matching circuit boards attached to huge heatsinks which form the side walls of the power amp.
"DYNACO 17-0002 REV A Copyright© 1992"
"MISAPPLICATION HAZARDOUS" means, do not touch the terminals!
Below are photos of my ST-200 from a previous article I wrote about it when I purchased it (also via eBay) comparing it to the Kenwood amplifier I had been using.
Notice the completely different design of the ST-200 compared to the layout of the ST-400 Series II images above.
Note the yellow serial number sticker on the ST-200. Also note that the RCA inputs are together compared to single RCA inputs on each end of the rear panel of the ST-400 Series II. The ST-200 has switched output for two pairs of speakers.
The ST-200 also utilizes a toroidal power transformer and matching left and right boards with large heat sinks for the power transistors.
A closer look at the PC board.
The toroidal power transformer close-up.
The ST-200 differs from the St-400 Series II in other ways. The small PC board above is for individual adjustment to each channel's volume.
Below are some of the very FEW photographs I could find of Dynaco ST-400 Series II power amplifiers I could find on the Internet.
Note the lack of a serial number sticker on this ST-400 Series II which was for sale in Canada. Other images of this follow further down in the article, but from the US.
These images are of a preamp/power amp duo for sale. I also found the same images, but larger when this pair was again offered for sale by a different seller. Note the lack of a serial number sticker on this ST-400 Series II as well.
Below are some images I had found earlier of ST-400 Series II power amplifiers. I spent years gathering a large collection of Panor-era Dynaco stereo equipment which I found on the Internet.
Note the "US Audio Mart" verses the SAME image having "Canuck Audio Mart" seen further above in the article. This amp has stickers on the rear which Bob's does not.
I often wonder why some folks post poorly displayed items for sale. Not that I am an expert photographer.
Years ago, I subscribed to several audio magazines and when I saw an add for the "new" Dynaco company, I wrote (yes, before the Internet was a widespread thing) a letter requesting information on their products.
These are what they sent me. When I saw the prices, I realized that I could not afford to buy anything but their cheapest item, the QD-1. YEARS later, I decided to sell these as a LOT. Stupidly, I did not SCAN them. Now that I think about it, I did not own a scanner back then. OK, now I will stop mentally kicking myself.
I chose to put these scans full sized. Some of them are not readable at the same size as the other images. Things highlighted in yellow are equipment I have owned.
These are scans I made of pages from the Orion Blue Book of AUDIO equipment. It includes original Dynaco equipment and later Panor-era equipment information and prices. If you look at the retail prices of the 1990's equipment, you can see why so few were purchased then and likely why the company went out of business. Which equates with why finding them for sale is such a rare and often pricey treat.
I have never had my hands on a ST-400 Series II power amplifier. I did own one of the original ST-400 power amps (below, that stack was for photographic purposes). So, I cannot comment on the weight (gotta be heavy!) or SOUND of it, but based upon the incredibly wonderful sound of my Panor-era stereo equipment, I am sure that Bob is enjoying it's musical output.
Yes, the four knobs AND the fuse holder are incorrect. It only came with one knob, So, these substituted just fine. My very first piece of REAL stereo equipment was that PAT-5 preamplifier which I built from a kit in 1976. FM-5 was a later (used) purchase as was the ST-400.
Above is a photo of all the brochures I had received from the original Dynaco company when I wrote to them in the 1970's.
This is the system which I have painstakingly assembled over MANY years of buying and trying equipment since 1976.
Below are links to two other articles I have written about latter-day Dynaco equipment.
Thank you for taking the time to read my humble blog. Feel free to leave a comment below or on Facebook.
September 12, 2023
#470
Well I guess the st-400 series 2 is a copy of a Sae A205
ReplyDeletehttps://www.diyaudio.com/community/threads/sae-a205-amp-mosfet.399149/