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
Alot of the collectable 70s pioneer/sansui mega receivers have an overly bass dominant sound...some would say 'tubby' quality...far from nuetral but kinda fun in a muscle car way...I didn't come into my own till the early 80s...when luxman and hk still made decent stuff...the hard part was finding good 2 way monitors ala BBC types...which are far more readily available today...but from a purely cosmetic and build quality standpoint...the vintage stuff has some merits...this is a crude generalization...but the low to moderate power offerings always seemed to perform better...the 70s amps listed above didn't hit my radar still much later...
Pubul57, aside from tons of repair and modification, my audio design experience revolves mostly around small-volume or one-off custom stuff for pro audio applications . . . various iterations of analog and mixed-signal "preamp"-type stuff. This has included mic preamps, electronic crossovers, long-line drivers and receivers, active bandwidth-limiting filters, small low-noise mixers, etc. etc., and various combinations of these building blocks combined into a single chassis. I used to get a lot of requests like "We need these PA systems to be at least 8dB quieter at the inputs to the mid- and tweet-amps, and get rid of that 'clippy sound' in the bass when it's really loud. Can you build something to do that?" And I would . . . and all kinds of similar stuff in FM broadcast and recording.

But I'm not an EE - my education is in classical music, and the way we learned about harmony, part-writing, counterpoint, form, etc. was to study the works of the masters (and the also-rans, too). I tend to take this approach to the study of audio design . . . since it's much more informative to analyze the harmony in Schumann's "Ich grolle nicht" than a silly textbook example, I'd rather listen to i.e. a DC-300 or whatever, then measure it and study its circuit design, than simply read about hypothetical circuits (and equations simply for their own sake) in a typical undergraduate EE text. The repair process is a natural method for analysis and measurement, and since I like to listen to music while I work . . . I've always kept a well-set-up amp/speaker system on my test bench, so I'm always trying to correlate what I hear to what I see and measure.

And I'm also generally a sucker for history, and love hearing/reading people's stories and narratives . . . hence this thread. Again, thanks to all for the contributions!
I had fun building the hafler pre and power amp kits;dh101 and the dh500 power amp.At this time of my early audio hobby the dh500 I thought was just awesome and produced the best sound driving my infinity speakers;the 500 still surfaces now and then with mods from musical concepts;
it was a pretty good performer for its time.
The DynaKit 120 circuit is a preamp on steroids. Output through a big capacitor: no transformer. Its sound quality was critisized until they come out with the conventional 150, which made the 120 sound good. I had both.

The Kenwood L-07M is a direct-coupled amp, input to output. It is really an analog-programmable DC power supply, with response time fast enough to play music. Response is DC to 100KHz. You have never heard bass until you try the L-07M.
Siliab, I am still running the 630,620, 600 Nakamichis. Bought them in 1977 and using Totem Mani's as speakers and Oracle Alexandria MKIII with B&O EN20 cartridge.

All sound great in my room, still!

Salut, Bob P.