2. amps-preamps
  3. 1322333418

How do we remember 1970s amplifiers?

I would be curious to hear some of the memories and impressions associated with the following short list of 1970s amplifiers:

- McIntosh "first generation" SS amps, MC2105, MC2505, MC2300, MC250, MC2100
- Dynaco Stereo 400 and Stereo 120
- Phase Linear 400 and 700
- Bang & Olufsen "slide rule" receivers (i.e. especially blackface Beomaster 4000)
- Original Ampzilla (not Son of Ampzilla)

I've chosen this list mainly because they cover a wide range of approaches to solving the issues of early semiconductor technology, and they were all pretty mainstream products in the U.S. I'm excluding the Japanese receivers/amps not out of predjudice; it's simply that the circuit designs varied quite a bit with each model, and thus harder to broadly classify their characteristics.

I'm interested in impressions of both sonic and non-sonic attributes, and a preferred ranking of the above, if you like.
kirkus
dividebytube
50 posts
 
I've owned the MC250 - the industrial looking 50WPC amplifier. It uses autoformers and actually sounds fairly tubey. Good bass, a little muddy in the mids, and a not very detailed treble. It had a bit of a grainy smear to the sound - at least with the speakers I had at the time. But still, it was a very enjoyable and musical amplifier, just not very high-end.

I've also used a (rebuilt) Dynaco ST-80. Like the ST-120, it's actually capacitor-coupled to the speaker, so some of the faults could be attributed to the bad electrolytics of the time. The only I rebuilt had modern caps and sounded half-decent. Certainly not world-class, but a nice little dorm amp or something for a second system. Again, it just had a slight grain and a slightly forward/etchy treble.
fstein's avatar
fstein
199 posts
 
Well, my Flame Linear blew up, as did my dyna 120.
Having worked my way thru the dyna line, and going by their reputation only, I rushed to sell my Mk 3's for the newer better solid state - big mistake, the magic went.
ajw_atlanta
1 posts
 
I also work in the hi-fi business and have been fortunate enough to change bits and pieces as I went. My very first system was an Apt Holman preamp / HK Citation 19 amplifiers (a pair bridged mono 220w/ch), a Micro Seiki MB15 / Micro Acoustics entry level cartridge with a pair of Yamaha NS100 monitors. I spent quite a lot of time listening to music back then!

Times have changed as well as the sophistication of my systems but the 70's was a fantastic time in audio! Loads of fun. Thanks for the trip down memory lane.
tbg
5,263 posts
 
I had a Dyna stereo 120 which had substitute transistors and never blew up. I used them on Rectolinear III speaker. I had the Phase Linear 700 with the Dayton Wright Electrostatics and the Watson Labs Model Tens. I also had the Ampzilla with Infinity 2000As. It is hard to say which of these gave the best sound. Probably the Watson Labs and PL 700. I never had any problems with the Phase Linear. I sold it to a disco and they blew it up in less than a month.

You neglected to add the Stereo 70, the Audio Research Dual 50, 51, 75A, 76 amps, and the Paoli 60M amps. The Dual 75A and Paolis were great on my Infinity ServoStatics. I keep this combo for five years.

This was a fun period for me with young kids, Hobie racing, and great sea food in addition to some good audio.
salectric
751 posts
 
My system in 1976 would probably still sound pretty good by today's standards. Here's the lineup:

Table #1--Rabco ST-4 with ADC XLM
Table #2--Thorens TD-124 with homemade pivoted arm and Decca Mk 5

Phono---homemade based on Trevor Lees circuit (supposedly a copy of the Paragon 10)

Linestage--homemade passive (pot in a box)

Power amp (100 Hz and above)---Dyna 70 with extensive mods

Power amp (below 100 Hz)--Williamson Twin-20 (Audio Amateur magazine project)

Speakers---KEF B200 in homemade transmission line; Fulton FMI-80 for mids; RTR ESR-6 electrostat tweeter
More to discover