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.
I had never liked Ampzilla, too rough sounding to me.

Phase Linear sounded dead, typical solid state sound of that age.

The one I liked most was SAE 2600. I used to own one driving a pair of Gale 401s, really sweet and dynamic sounding.

These is just my opinion of course, others will surely disagree.
My memories of the Dyna 120: BANG! Blew up all the time; warranty repairs drove Dynaco out of business. I remember them more from the middle 60s. I had an SAE but my Quad 303 was a better amp.
I think my ability to afford higher end gear was transitional in that decade. My memories are limited to the early 80's and NYAL which was my first experience of the warm, lush sound of tubes, along with the Dynaco 70. What I have set in my memory of those is what I'd describe as a more romantic sound...certainly colored, a bit mushy perhaps (what a horrible adjective to apply to audio reproduction, but it's more an emotion I'm after there). I doubt I'd like them if I heard them today, but who knows. I was completely unimpressed by muscle amps like Phase Linear - they just gave me a headache. Now there were some Krells from that period, and perhaps a Levinson, that really turned my back around to seeing what SS could do right without the associated headaches.
Some model Yamaha receivers were very good for the small amount of money they cost. A few were as low as $149.00 or $199.00 including tuner.

BGW was a great amplifier for commercial application, a southern California company that came to market about 1971 as I recall.

I sold a few to "rock and roll" stereo customers, certainly it was a superior sounding product than the Phase Linear that was more popular at that same time.

Dave O'Brien of McIntosh clinic fame tested lots of Kenwood KA6000 and spoke highly of them. About 50 watts per channel at multiple output impedances and sturdy power supply.

Link below shows it with matching tuner of same era.
My first excursion into the "high-end" came in 1984 when I stepped up from my Fisher X-101 with Sanyo turntable (other components?) to a McIntosh system. I purchased a used C-26, MC-2505 and new XL-10 outfit, along with a new Thorens TD-146 with Signet TK3A(?). I was so sure that McIntosh was the ultimate that I don't even recall listening to the system before bringing it home.

To make a long story short, I really tried to like it, but to my chagrin it really didn't do it for me. It seemed muddy and uninvolving. This stereo stuff wasn't as easy as I thought!

Oh well, that began my (futile?) search for the holy grail of audio!!
A friend found the Dynaco Stereo 400 on a thrift store, rated at 200wpc into 8 ohms, 300wpc into 4 ohms. A beauty, but this one needed several fixes. Some people say its harsh and grainy.
We bought a Cerwin-Vega A-1800 to power a small PA in 1977. As with some of the amps on your list this was the first generation of higher powered solid state amplification so there was little to compare. When the band split I got the amplifier. I also had a pair of Marantz 8B's at the time. I never did warm up to the Vega as a playback amp so it did duty in my DIY Bass amp rig which never left the house.

In the mid nineties I decided to go through the Vega and upgraded as many parts and wire as I could. Surprisingly, it warmed up and became fairly listenable.
I had a Phase Linear 400 driving a pair of Bose 901 original series in 1972.

At that time it was the best amp/speaker combination I had owned.

Preamp was a Dayton Wright; don't remember the model but it was my first preamp without tone controls.
In the 70's, I was still a receiver dude. Separates were a little too esoteric for me back then. The thought of a separate amp was light years away.
I had a Kenwood 8000 and something integrated amp. I think it put out 75 wpc. I used it with Rectilinear 3a speakers and the sound was excellent. I have fond memories of that system. My turntable was a Thorens TD160 with a Shure V15 cartridge.

Should have kept the system.
Back in the 70s, I used to own a Crown IC 150 pre and DC 300 amp. Speakers were Infinity 2000a electrostats (tweeters). TT was a Thorens TD 160 w/ Ortofon cartridge. I loved that system and had it for more years than I can remember.

The Crown gear never stopped working. I sold the IC 150 about 5 years ago. Just sold the DC 300. About 2 years ago, I bought a DC 300A for mt son. The factory rehabbed it and the amp sounds great on his system and works perfectly. His pre is an ARC SP 9 -- also immortal.

I have a D 150A II in the house as a back-up amp. One day I'll hook it up into my system to check out how it sounds compared to my ARC VS 115. I'm prepared to be surprised. :)
I'm still using the the Dynaco. It was a "Quad" when I used it in the 70's. I had it mated with my "Quad" Phase Linear 4000. Since that time I converted it to stereo.

Without a doubt I thought everything I had was "hot stuff" at that time. Now, I use the still powerful Dynaco in the entertainment room where nobody listens anyway, but it bangs out that bass.

I guess your question is how we remember, as opposed to how we compare with today's amps; and I remember it as "all good".
While I remember it as "all good", compared to today; that stuff would be junk.
You forgot the Audio Research D150 and D75 around that time, late 70's. I ran a high end hi fi store. We had Ampzilla's (nicer sounding than the Flame Linear) and BGW's (too harsh) or the Crowns (REALLY harsh). SAE was around then too, had some cost effective stuff that competed with the Crowns and Phase Linears well. Nothing sounded better than the Audio Research in my store. I had Magnaplanars, Dahlquist DQ10s, KEF104's (my favorite of the day) and DCM Time Windows all in my high end room. An Audio Research SP3A hooked to a AR D150 amp to a KEF104 was the best we had.....Nice Micro Seiki turntable with a Grace tonearm and a Dynavector cartridge.....
This is slightly before the 70s, but my old man had a Fisher tube receiver, a Garrard Lab 80 turntable with an Empire cartridge, and AR speakers, and he ran that kit well into the mid 80s. Lamp cord for speaker wires, with the speakers just lying on the floor.

He was just here for Thanksgiving and couldn't repeat often enough how completely insane modern hi-fi is (which translates to "You may be 43, but you're still a schmuck), and he can't understand why anyone would want/need anything more than a Bose table top thingy.

Despite this bravura, he did take the time to listen to a Van Karajan Mozart CD all the way through three times. So how ridiculous was that, pop?
Good thread. Brings back memories to my Dynaco SCA 80 and then Stereo 300/ Pat 5 mated to my large Advents. Boy did that set up sound good back then.
I seem to remember Phase Linear amps had a reputation for catching on fire. That made an impression on my memory.
Well it was from an earlier time, but what I had in the 70s - the MAC MA 230 hybrid integrated. I remember it as being the greatest piece of gear of all time. I assume I was delusional, but I did not know any better and so it was the greatest piece of gear of all time.
Loved Phase Linear 400 driving ESS Towers, but my budget dictated Yamaha integrated, which I still have (upgraded by Ezekiel).
Not trying to be argumentative. As I mentioned above, I used to own Crown gear. As I recall, it was considered SOTA in its day. I beieve it was top rated by J. Gordon Holt's Stereophile (before it accepted advertising) back in the 70s and was used to drive the most demanding power hungry hi-end speakers, e.g., Tympani panels, etc.

Yet, it's earlier repuattion does not appear to have survived time. Just a question: why is that? I admit that I have not critically listened to Crown gear recently nor compared it to my current gear. Perhaps some of the oldheads out there can tell me why the old vintage Crown gear has fallen out of favor. Maybe it was the use of copious amounts of NF to achieve spectacular performance stats??? Dunno.

Loved that old stuff. Happy Holidays!
The closest I come to your list was a B&O turntable with the non pivoting tonearm and snap in cartridge. I liked it a lot.
Aside from that was a Quad 303 preamp and a BGW500D amp that brought me lots of joy. The rest is quite foggy.
I know this is not from your list but, see what you started.
Wow, I'm really enjoying everybody's comments, thank you. I particularly like the venomous reactions to the Phase Linear amps . . . as I think it's in so many ways the poster child of 1970s solid-state amplification.
Yet, it's earlier repuattion does not appear to have survived time. Just a question: why is that? I admit that I have not critically listened to Crown gear recently nor compared it to my current gear. Perhaps some of the oldheads out there can tell me why the old vintage Crown gear has fallen out of favor.
Bifwynne, these sorts of questions are what I had in mind to discuss when I started the thread . . . and I'd like to try as much as possible to avoid the subject of NFB, as it has a way of hijacking threads. Specifically, I think the "1970s transistor sound" is related much more to poor linearity in several key circuit areas, principally the "quasi-complementary" (all-NPN) output stage and its inescapable notch distortion.

But the Crown gear is an excellent subject, especially as it compares to Phase Linear . . . I have my suspicions that Bob Carver actually derived his designs from the Crown DC-300 schematic. They both use quasi-complementary output and driver stages, although there's a subtlety in the Crown design that's not immediately obvious: the drivers operate in Class A and in parallel with the output stage through the crossover region, smoothing out the notch distortion to a significant degree. It also makes the whole thing far less temperature sensitive for its bias conditions.

Although I don't know the exact chronology, I find it interesting that when Crown added an opamp front-end to the DC-300A (and D150) that Phase Linear followed suit by doing the same thing with the 700 Series II and 400 Series II. But Carver's amps still show the earmarks of a cheap copy, especially how he cut costs significantly by simply using an electrolytic to bootstrap the voltage-amp load, rather than the true current-source transistor powered off a separate supply rail in the Crown design. Carver was also obviously having stability issues with all these amps, as shown by the ferrite beads and picofarad-value capacitors "liberally sprinkled throughout the schematic" (to borrow an expression from Douglas Self).

All in all, from today's perspective both are dated designs and have a couple of the same flaws, but the Crown is a thoroughly well-optimized and beautifully engineered amplifier, and I think this shows in its sonics and its remarkable reliability. I'd say that with easier loudspeaker impedances, one could still do much worse than a DC-300 today.
My sonic memory of solid state amps from that era is that they never pleased me as much as the tubed Dynaco amps from a decade before.

I had only experience with solid state amps like mid 70's Pioneer beheamouth receivers, Yamaha A1 integrated.I was a newbie.
Before that it was a mono ,tube system built into a tv console. when I was growing up.

The solid state amps of the day ,never had the same sense of realism as the old tv system had, but it was newer and just had to be better and so I left it at that.I was a newbie.

Then a friend of mine got a used Dynaco stereo 70 and Pas 3 pre amp and his Ls3/5a speakers went to a new level.
We had the same Yamaha intgrated amp and speakers, cables etc.In those days if I heard a sound I liked, then I went out and duplicated it.I was a newbie.

So I went out and got a tubed Dynaco set up and was quite happy.

In retrospect, I should have quit while I was ahead.

But being a newbie, I flitted from one new "best" system to the next, and near the end of the 70's or early 80's bough a NAD 3020.

Not as good or as pleasing a sound as the tube stuff, but still better than the solid state amps I had been using in the 1970s.

This is the reason I find the new fascination for 70's solid state stuff so perplexing.
From someone who was there and listened to that stuff when it was new and all the rage, and then moving on to better things,I just can't see the interest in any of it.

Sure there's lots of features and lights and bells and whistles and shiney knobs, but at the end of the day, it's the sound that comes out that counts.

But then again this hobby has verred so far off the path from where it was when I started that, trying to achieve the sonic truth has become a no no, and any gear that is not coloured and covered in a hazey cloud of electronic mist is seen as too analytic and fatiguing.

I'll take my coffee black please, just make it a premium blend.
Transaudio-was that Trancendental Audio on the Niagara Blvd?
I remember it well when I was a newbie.

They had some Dan fellow working there that I think tinkered around with amps and may have sold a couple over the years.

I believe he is still at it to this day.
Sold my car to buy a high end system as a Freshman in college -1977. Talk about a killer dorm system. First amp was a Phase Linear flamed (literally) -- However, I thought it sounded very good. Then went with a fabulous Harman Kardon Citaion 16 amp and a GAS Theadra preamp, Dahlquist DQ10's (Denon TT w/ Supex 900 MC cartidge). It was fabulous. The HK amp was a tank and sounded superb. I replaced it with an Ampzilla in the 80's and regretted it. The Ampzilla was always breaking and was not as smooth as the HK...much better mids with the HK. The Ampzilla was very transparent sounding and had major balls in slam and low end energy. BTW, I got the "bug" after owning a nice Yamaha receiver w/ Infinity speakers. The rest is history and am still spending way too much money on stereo gear.
Kenwood L07M (mono) was reasonable as was the Grandson of Ampzilla. I had heard the ampzilla, it was rough around the edges, I had heard Flame Linear 400 and 700B, harsh.
Pioneer had some old Class A amps that I recall sounding quite nice... They were Series 20 or 30, don't recall exactly.... Compared to today, no contest
My system in 1978 was a GAS Son of Ampzilla, GAS Theadra preamp and a GAS Sleeping Beauty cartridge mounted on a JVC Direct Drive turntable. Speakers were Rectilinear 7's. Never could get the 7's to sound as good or better than the old Rectilinear 3a speakers that I traded them for. I also had a Sansui Tuner which I should have kept.

I loved my GAS electronics, quite smooth yet revealing in their day. The piece de resistance of my system was my Teac reel to reel recorder (can't remember the model).

I was working in retail at a mom & pop audio store so I changed my equipment quite frequently back then.
Sweet memories....
I owned a Phase Linear 200B (which outperformed a Quad 405 in a straight shoot-out).
Lacee, thanks for bringing up the little 20W NAD . . . this is the perfect 1980s equivalent of the Phase Linear amps. I serviced these back in the day, and even had the "Power Envelope" decendent (3225PE?) as a test-bench amplifier for several years. In contrast to the big, "all technical" 1970s aesthetic, it was small, lightweight, low-powered, and simple-looking. But like the Phase Linear, it was cheaply made and unreliable . . . and the sonic signiture was filled with exactly the opposite types of problems.

I will say that the preamp sections were pretty decent, maybe even good considering the low price . . . but the power-amp section was an absolutely atrocious piece of engineering. The key "feature" was that it didn't have emitter resistors on the output transistors, and I assume that this was an attempt to reduce notch distortion. But even if this had been a good idea (which it wasn't) . . . they then chose the absolutely cheapeast big power transistors available (2N3055/MJ2955) that have poor linearity even by 1970s standards. The result is that even with enough idle current to make it run pretty toasty, it was still really operating in underbiased Class B, and put out a whole slew of nasty harmonic and intermodulation distortion products. This may have been "redeemed" somewhat by the single-transistor input stage, which guaranteed a big helping of even-order distortion as a big sugary coating for that rancid-piece-of-meat of an output stage.
Not as good or as pleasing a sound as the tube stuff, but still better than the solid state amps I had been using in the 1970s.

This is the reason I find the new fascination for 70's solid state stuff so perplexing.
From someone who was there and listened to that stuff when it was new and all the rage, and then moving on to better things,I just can't see the interest in any of it.
Well, selective memory seems to work both ways . . . we overwhelmingly shun what was in vogue in some eras, and romanticize others. One of the reasons why I mentioned the 1970s B&O receivers was because (like the NAD amps of the 1980s) they offered a modestly-powered, domestically sensible alternative to the "high knob-per-dollar" mainstream aesthetic. They were vastly better engineered than either the Phase Linear or the NAD, but had a few quirks of their own (esp. cultural?) . . . I'm wondering whether they're remembered similarly to some of the more high-profile [sic] pieces of the decade.

The music was so much better back then that we didn't know the equipment was lousy, and a good time was had by all.

Since everything is relative, and none of us had rigs much better or much worse than the next guy; we all thought our rigs were killer at that time.
My first stereo was an Altec-Lansing 911A compact in 1972 for $419 (about $2160 in today's money). It aspired to rare heights for a compact--it incorporated a (slightly de-tuned) Altec 44 wpc receiver, Garrard SL95B (their top line consumer deck until the Zero 100), Shure M93ED, and Altec 887A speakers, an 8" 2-way sealed cab. The tuner section was excellent and the amp section wasn't too shabby either.

A couple years later I was working at a hi-fi store in SoCal where our amps were Phase Linear (we needed their 700 to power the Ohm F's), Accuphase, Marantz Pro (a good lie at the time), Crown, and a few SAE's left over.

One day We hosted a Marantz clinic where an audio engineer would measure (for free) power and distortion on any unit you could lug in. I proudly brought in my Altec 911 and was disappointed to find that its 44 wpc at mid-band dropped off to 27 wpc at 20 Hz. Turns out Altec had shrunk the power supply (compared to the receiver it was based on) to fit it in the cabinet with the turntable.

There was an orphan pair of entry-level SAE components back in the storeroom--the Mk XXX preamp and the Mk XXXIB power amp. I picked those up and started using them instead. The amp was rated at around 50 wpc but the tests at the time indicated it put out more like 70, but the cool thing is it had textbook square wave response (even better than the Crown) in the bass. You could really hear that--any speaker it powered had cleaner, tighter, more extended bass with this thing than with a receiver.

SAE was also founded by James Bongiorno who founded G.A.S. and also co-designed the Dynaco 400. As I remember it, however, the treble was a bit hot. Still, I wonder how much our perception of the separates of the time is influenced by the way we used them. We had no awareness of a "burn-in" period, let alone a warmup period for solid state. We plugged things in and immediately started evaluating them. Now I never turn my power amp off, and it was pretty edgy when I first plugged it in and turned it on.

I also had the privilege of meeting John Iverson and spending a day with him as he demonstrated his incredible A-75 class A power amp into his own speakers. Until that day I'd never known that hi-fi could do *that*!

Currently my #1 power amp is just past the '70s--the 1981 Heathkit AA-1600. I got it used for $239 and it makes my jaw drop. Just two years into the '80s, it is so far beyond the amps of the '70s. It reminds me a lot of the 1990-ish Jeff Rowland Design Group amps.
Dynaco Stereo 300 / QSA300 Power Amplifier





Rated 4-channel Power Output: 75 watts continuous average power per channel into 8 ohms (40 watts per channel into 16 ohms) 20-20,000 Hz, at less than 0.25% total harmonic distortion. Distortion reduces at lower power outputs.

Available 4-channel Output Power:

20-20,000 Hz, all channels driven, 0.25% maximum THD:

75 watts continuous average per channel @ 8 ohms;
100 watts continuous average per channel @ 4 ohms;
40 watts continuous average per channel @ 16 ohms.
Stereo Operation Available Output Power:

Low Impedance Mode Connections:

80 watts continuous average per channel @ 8 ohms;
150 watts continuous average per channel @ 4 ohms;
200 watts continuous average per channel @ 2 ohms;*
High Impedance Mode Connections:

80 watts continuous average per channel @ 16 ohms;
150 watts continuous average per channel @ 8 ohms;*
* 5 minutes sustained full power limit without a fan.

Power at Clipping, 1 of 4 channels, 2500 Hz, less than 1% distortion:

90 watts @ 8 ohms;
130 watts @ 4 ohms;
45 watts @ 16 ohms.
Power at Clipping, Each Stereo channel, 2500 Hz, less than 1% distortion:

Low-Z mode:

95 watts @ 8 ohms;
160 watts @ 4 ohms;
240 watts @ 2 ohms.
High-Z mode:

160 watts @ 8 ohms;
90 watts @ 16 ohms.
Intermodulation Distortion: Less than 0.25% at any power level up to 75 watts rms per channel into 8 ohms with any combination of test frequencies. Distortion reduces at lower power levels.

Half-power bandwidth: 37.5 watts per channel at less than 0.25% total harmonic distortion from 5 Hz to 50 KHz into 8 ohms.

Frequency Response: +0, -1 dB, 10 Hz to 40 KHz @ 1 watt into 8 ohms; ±0.5 dB, 20 Hz - 20 KHz @ 75 watts into 8 ohms.

Hum and Noise: Greater than 95 dB below rated output, full spectrum.

Input: 35,000 ohm load; 1.0 volt for 75 watts into 8 ohms.

Semiconductor Complement: 52 transistors, 40 diodes.

Slewing Rate: 7 volts per microsecond.

Damping Factor:

Greater than 80 to 1 KHz into 8 ohms;
Greater than 50 to 10 KHz into 8 ohms.
Channel Separation: Greater than 70 dB by IHF standards.

Connectors: Inputs: phono jacks. Outputs: Color coded 3-way binding posts with standard 3/4" spacing.

Dimensions: 18-1/4" wide, 14-1/2" deep;, 7" high panel, 17-1/2" wide. Add 1/2" for feet.

Shipping weight: 58 lbs. Net weight: 52 lbs.

Power Consumption: 120 VA quiescent; 10 amps maximum; 50/60 Hz, 120/240 VAC.

Designed by:

Harry Klaus

Year Introduced:



$269.00 kit
$399.00 assembled


Basically two ST-150 units in a single chassis, with separate power supplies. Usable as four independent channels or as a bridged stereo amplifier with 300 watts per channel. The MC2/MC3 meter kits provided output monitoring.



This page created and maintained by Greg Dunn.
Copyright © 2000 Greg Dunn

I originally purchased this as a 4 channel amp which I used with my "Quad" Phase Linear 4000 pre. At that time, I thought it was "hot stuff".

Now, it is in use as a bridged stereo amplifier with 300 watts per channel. It sounds like what it is, "A big powerful mid fi amp". It works fine in our entertainment room where at least three conversations are always going on at the same time.
SAE was also founded by James Bongiorno who founded G.A.S. and also co-designed the Dynaco 400.
I thought Bongiorno was just one of several people who designed different SAE products (not one of the founders), but I may be wrong. I had forgotten his connection to the Stereo 400; thank you.

One thing about the Dyna 400 and the GAS products was that they didn't skimp on the quality of the silicon . . . these were all fully-complementary output stages that used the transistors' characteristics very effectively. The GAS amps extended the complementary-pair thinking through to the input and voltage-amp stages, which IMO deserves respect for its conceptual elegance, even though there are some fundamental problems with its implementation. This fully-differential approach is also a hallmark of many of John Curl's designs, though I would hesitate to imply that the Levinson designs bore influence from the GAS.

But the Ampzilla was hugely influential . . . it did start out as a project amplifier with the schematic published in a magazine, and like the Williamson amp published 25 years or so before, bits of it seem to turn up everywhere. The current crop of McIntosh SS amps (from approx. the mid-1990s) use a front-end that strongly resembles Ampzilla's, with a few refinements.
Currently my #1 power amp is just past the '70s--the 1981 Heathkit AA-1600. I got it used for $239 and it makes my jaw drop. Just two years into the '80s, it is so far beyond the amps of the '70s. It reminds me a lot of the 1990-ish Jeff Rowland Design Group amps.
I remember these from the Heathkit catalogs, and dug up a schematic . . . and from the way it looks on paper, I'm not surprised that you like the way it sounds. It's kinda like a simplified Dynaco 400, but with the biggest flaws fixed (esp. the intermediate stage with its current-mirror).
I remember my dad replacing his Fisher receiver (complete with built-in tape deck) and Fisher speakers with a new McIntosh 4100 receiver, DCM Time Window speakers, and a Nakamichi cassette deck. The difference in power and sound was incredible and formed the basis for my interest in audio. I have since moved the Mac/DCM combo to a second home, and it still sounds great.
I had a couple of NAD 3020(bought new for the princely sum or $200.00 each)and never had a problem.

Maybe I was lucky, but then I've never had problems with any of my gear.

The cost to performance of the Nad was it's biggest selling point.

It also got lots of rave reviews and if I can remember, was one of very few components to ever get positive press from all the audio rags back then.

How would it perform today?
I think there is a comparison of the old 3020 to a present day unit, and the reviewer tended to still find quite a few nice things to say about it.

Sorry if it measured so poorly on the test bench or had such inferior parts, but we are talking $200.00 new.
I would presume the better measured gear with the superior parts also cost more, so really all that you can compare is how the sound of the parts used compared, and to my ears back then on Rogers Ls3/5A speakers and later Mission 770 speakers, the Nad was good enough to not warrant any updates for a couple of years.
Even then I used the pre as a phono stage and then used the two units I had as dual mono pre amps with a single power amp.

I later got into Conrad Johnson MV75A-1 and Premier Twp pre amp,and Acoustat medallian 3 stats, and onto my first foray into the High End of that era.

This was the early 80's, the gear was better no doubt about it to my ears,and yet the Ls3's are still quite well regarded and fetch more used today than I would have ever imagined back when I bought them new for $400.00 bucks.

Yes the good old days,when $600.00 bought you a decent integrated amp and a pair of speakers.

But in keeping with the OP, I still remember 70 amps as being feature laden ,pricey units that could be bettered sound wise by simpler units costing far less.

There was a thickness to the sound of some of those receivers, like my 100 watt Pioneer or thinness like the Yamaha A-1,that never really clcked with me.

The sound of 70's amps was all over the map, so pick your colouration and sing the praises.

Time marches on things get better, and there are still some sonic bargains to be had.Those who think that great sound is only available to the rich who can afford $75,000.00 amps, and turn to vintage gear for solace, needn't do so.

I really am quite impressed with my 2 Watt DecWare Zen Select amp.

It is the spirit of the 3020 today.
I have a mint Phase Linear 400 Series 2, in which I installed DC protection circuitry a couple of years ago. I have all new electrolytic caps waiting to do a total recap, I just haven't gotten around to it yet. To my ears, it is not a bad amp at all. Not the finest, but better in some ways than some other amps of that era that I've had in my collection.
Lacee, you're probably right that I was a bit too harsh on the 3020 . . . NAD's manufacturing quality steadily declined through the 1980s, then plummeted under the ownership of KH America in the early-1990s . . . and this is when I serviced them. It seemed that the late-1980s stuff failed at least twice as often as that from the early-1980s, even though they were newer. The current product of the time (I'm thinking of the 505 and 705) had out-of-box failure rates of at least 25%.

The 3020 was indeed cheap and it did have a nice phono preamp, this was probably the best part. And after two failures in two years with my 3225PE bench amp, I added a pair of 0.33-ohm emitter resistors and switched to 2SC3281/2SA1302 output transistors, then re-biased. It completely transformed the performance . . . the distortion was reduced by something like 75% leaving overwhelmingly even-order products. The little NAD then sounded quite nice with my KEF C25 bench speakers . . . which I guess was exactly the kind of setup for which it was intended.

Still, I don't know whether to praise the design because it didn't take many changes to make it a nice little amp, or to be really annoyed because these changes would have cost less than $2.00 per unit in production . . . probably cheaper if you factor in volume pricing of the day and the better reliability during the warranty period. With the Phase Linear 700 it was far more clear-cut -- the circuit was wholly unsalvageable. The best thing for one of these is to use the case and heatsinks (but NOT the transformer) for a project amp.
My AR receiver gave me many years of joy, but the sound is only in my imagination now. I was seventeen; it was a very good year...
Mostly I remember my speakers (Kef) and 'tables (several). My only memorable electronics were SS models from Audire - the Diffet pre and a power amp which I can't recall the model designation of. Purchased cheap at Crazy Eddie, a large New York discount chain that somehow got the Audire line.

IIRC, they sounded quite good. Of course, that's a damn big "IF" in the IIRC. Not too much later I bought a pair of the earliest production Quicksilver mono amps which - I think - were simply great amps (of their type).

I lucked into owning, perhaps the sexiest components of all time, the Nakamichi 600 cassette deck, 620 100 wpc amplifier and 630 tuner/preamp. Spinning the tuning wheel of the 630 was a particularly sensual experience, as was the light show of the center-tune indicator. The system also featured a Philips 312 table with a Signet TK9E cartridge, and A/D/S 300 speakers with an M&K subwoofer. This system was very good with the classic rock I was mainlining at the time but considerably less good with the Jazz I was beginning to become fascinated with. I remember acoustic bass sounding particularly hollow and disembodied through this system. In retrospect, it was most probably the tendency toward one-note bass of the subwoofer that was mostly to blame.

Economic necessity led to my parting with the 620 and the 630, but I still have the 600, which still sounds great when properly setup. It didn't take long to find components that sounded considerably better, but I have yet to own anything nearly as great looking.
Lacee , so pleasant to read your comments, they are so parallel to my own. The store I worked at was a little place called Wack Electronics in Milwaukee Wisconsin-from 1975 to about 1977-then to a sound contractor, then back to the store until I became a rep in 1980. You are right about the tube stuff, it WAS better even then. (McIntosh too, but I wasn't a dealer) As a rep, I reprsented Jon Dahlquist, NAD, the folks at Crown, and Joe Grado- Proton too when it arrived. It was quite a time in hifi, I was a little late to party, there was so much business, so many hobbyists buying stereos in the 70s. By 1980 it was changing, rack systems where coming to big box stores, reel to reel was fading as Nakamichi took off. I so remember that Advent cassette recorder! There many very nice people in high end hi fi in those days, I think its still this way.

A DC300 in 1975 was a different beast compared to the competition than in 1980. Flame Linears in 1978 or so where the first company to meet the "dollar per watt" ideal, and at 399, the best bargain going. But boy they didn;t like to messed with. Crowns would work and work. But on something like an electrostat? Yuck! The Audio Research was smooth as could be.

NAD< what wonderful stuff in the time of the 3020, the 7020. That stuff STILL sounds good. A NAD 3020 and pair of little Fried speakers was fantastic

I eventually got more into pro, learning about live sound and installed sound where Crown eventually migrated when hi fi dried up. By the 90s it seemed high end hi fi stores where reduced to one per 1M market. "Listening to records" was no longer the cool hobby!

By the way, I just bought a Stromberg Carlson 1939 AM tube radio I found on ebay, with the acoustical labyrinth system, the very first transmission line bass system. VIntage Hi FI is still just as cool as it was new!

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.

11-29-11: Kirkus

--->SAE was also founded by James Bongiorno who founded G.A.S. and also co-designed the Dynaco 400.

I thought Bongiorno was just one of several people who designed different SAE products (not one of the founders), but I may be wrong. I had forgotten his connection to the Stereo 400; thank you.
You're right. I knew he was involved; I thought he had founded it, but that was Morris Kessler, with whom I'm not familiar. It looks like Bongiorno was an early advocate for bigger power supplies and wider bandwidth for better behavior into reactive loads and better dynamics. Bascomb King was also a collaborator on Ampzilla, according to a conversation I had with his son. It may explain the rave review Bascomb gave Ampzilla in Audio Magazine at the time.

--->Currently my #1 power amp is just past the '70s--the 1981 Heathkit AA-1600. I got it used for $239 and it makes my jaw drop. Just two years into the '80s, it is so far beyond the amps of the '70s. It reminds me a lot of the 1990-ish Jeff Rowland Design Group amps.

I remember these from the Heathkit catalogs, and dug up a schematic . . . and from the way it looks on paper, I'm not surprised that you like the way it sounds. It's kinda like a simplified Dynaco 400, but with the biggest flaws fixed (esp. the intermediate stage with its current-mirror).
I'm stunned every time I listen through it as I am right now. There is none of the edginess or midrange/treble harshness that described the typical '70s big power amp.