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  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  (System | Threads | Answers | This Thread)

  Responses (1-72 of 72)
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11-26-11   I had never liked ampzilla, too rough sounding to me. phas ...   Sidssp

11-26-11: Stanwal
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.
Stanwal  (System | Reviews | Threads | Answers | This Thread)

11-26-11: Jax2
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.
Jax2  (Reviews | Threads | Answers | This Thread)

11-26-11   Some model yamaha receivers were very good for the small amo ...   Albertporter

11-26-11   My first excursion into the "high-end" came in 198 ...   Minkwelder

11-26-11: Singleendedsingle
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.
Singleendedsingle  (Threads | Answers | This Thread)

11-26-11   We bought a cerwin-vega a-1800 to power a small pa in 1977. ...   Vicdamone

11-26-11   . in the 70's, i was still a receiver dude. separates were ...   Mitch4t

11-26-11   I had a phase linear 400 driving a pair of bose 901 original ...   Audiofeil

11-26-11   I had a kenwood 8000 and something integrated amp. i think ...   Stereo5

11-27-11   Back in the 70s, i used to own a crown ic 150 pre and dc 300 ...   Bifwynne

11-27-11: Orpheus10
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".

Orpheus10  (Threads | Answers | This Thread)

11-27-11   While i remember it as "all good", compared to tod ...   Orpheus10

11-27-11   You forgot the audio research d150 and d75 around that time, ...   Transaudio

11-27-11   This is slightly before the 70s, but my old man had a fisher ...   Grimace

11-27-11: Markpao
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.
Markpao  (System | Threads | Answers | This Thread)

11-27-11   70's amplifiers were comparable to 70's clothing. loud and o ...   Isochronism

11-27-11   I seem to remember phase linear amps had a reputation for ca ...   Bizango1

11-27-11   Well it was from an earlier time, but what i had in the 70s ...   Pubul57

11-27-11   Loved phase linear 400 driving ess towers, but my budget di ...   Jl35

11-27-11   Not trying to be argumentative. as i mentioned above, i use ...   Bifwynne

11-27-11   Apt amp and pre,most realistic sound 4 the buck ever !   Schubert

11-27-11   The closest i come to your list was a b&o turntable with the ...   Nonoise

11-27-11   Wow, i'm really enjoying everybody's comments, thank you. i ...   Kirkus

11-27-11: Lacee
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.

Lacee  (System | Threads | Answers | This Thread)

11-27-11   Transaudio-was that trancendental audio on the niagara blvd? ...   Lacee

11-27-11   Sold my car to buy a high end system as a freshman in colleg ...   Jeffga

11-27-11   Kenwood l07m (mono) was reasonable as was the grandson of am ...   Timlub

11-27-11   My system in 1978 was a gas son of ampzilla, gas theadra pre ...   Stereo5

11-28-11   Sweet memories.... i owned a phase linear 200b (which outper ...   Peterb

11-28-11   Lacee, thanks for bringing up the little 20w nad . . . this ...   Kirkus

11-28-11   the music was so much better back then that we didn't know ...   Orpheus10

11-28-11: Johnnyb53
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.

Johnnyb53  (Reviews | Threads | Answers | This Thread)

11-29-11: Orpheus10
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.

Orpheus10  (Threads | Answers | This Thread)

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.

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).

Kirkus  (System | Threads | Answers | This Thread)

11-29-11   I remember my dad replacing his fisher receiver (complete wi ...   Goblue711

11-29-11   i had a couple of nad 3020(bought new for the princely sum ...   Lacee

11-29-11   I have a mint phase linear 400 series 2, in which i installe ...   Gbart

11-29-11   Lacee, you're probably right that i was a bit too harsh on t ...   Kirkus

11-29-11   Kirkus, do you design gear? seems like you know a lot about ...   Pubul57

11-29-11   My ar receiver gave me many years of joy, but the sound is o ...   Rgs92

11-29-11   Mostly i remember my speakers (kef) and 'tables (several). ...   Martykl

11-29-11   I lucked into owning, perhaps the sexiest components of all ...   Siliab

11-29-11   Lacee , so pleasant to read your comments, they are so paral ...   Transaudio

11-29-11   Alot of the collectable 70s pioneer/sansui mega receivers ha ...   Phasecorrect

11-30-11   Pubul57, aside from tons of repair and modification, my audi ...   Kirkus

11-30-11   I had fun building the hafler pre and power amp kits;dh101 a ...   Rleff

11-30-11   The dynakit 120 circuit is a preamp on steroids. output thr ...   Eldartford

11-30-11   Siliab, i am still running the 630,620, 600 nakamichis. bou ...   Inpepinnovations

11-30-11: Johnnyb53

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.

Johnnyb53  (Reviews | Threads | Answers | This Thread)

11-30-11: Transaudio
So few remember the whole David Halfer kit thing. The Dynaco's were so good, Halfers were equally good to their time in SS. Hafler did OK but eventually got bought by Rockford Fosgate, who also owned Accustat. I forgot his name that designed all those Accustat TransNova amps, but (memory fuzzy) he was involved with Halfer later, wasn't he? I had an interview with Halfer in the 90's (they were all pro by then), in Tempe Arizona.

Hey anyone remember when Summer CES (high end suites) was at Hotel Congress in Chicago? That was about the early 80s and all those folks would be there.....the big companies where all at McCormick Place. In winter, it was Vegas and the Riviera for the high end and everything else was at (a much smaller) LV convention Center.

Transaudio  (Answers | This Thread)

12-01-11 is the kenwood ka 6000 by modern standards?   Phasecorrect

12-01-11: Orpheus10

Either Hafler, or Dynaco could be transformed into true "high end" amps by simply substituting their existing parts for the best parts available today.

Successful businesses were created doing just that. When "Black Gate" capacitors were available, I replaced every electrolytic in every piece of equipment I own with Black Gates. That was with the exception of huge capacitors in power amps, but all other lytics in everything from reels to DACs were replaced with Black Gates.

If the replacement of a single part can upgrade a piece of equipment, imagine how replacing all of the parts would affect that piece of equipment. It's quite possible that some highly regarded "high end" amps are essentially "Haflers" or "Dynacos" with different parts.

Orpheus10  (Threads | Answers | This Thread)

12-01-11: Pubul57
"It's quite possible that some highly regarded "high end" amps are essentially "Haflers" or "Dynacos" with different parts." Amen.
Pubul57  (System | Threads | Answers | This Thread)

12-01-11   I loved my kenwood...ka-7100 of the late '70s. good with ...   Magfan

12-02-11: Transaudio
Some of those old designs were pretty good and while the art has moved forward on a lot of amp features (protection, thermal and short monitoring, metering) sound was quite good in many of them. Just listening to an old mac amp is a good example of this. That Audio Research (tube) amp line in the late 70's was darn good. Dynaco's too.

I think long term amps will mean less to the market as active speakers become more and more important over the next years. Older preamps will likely gain in importance-for the front end will be ever more obvious.


Transaudio  (Answers | This Thread)

12-03-11   Eldartford brings up an interesting subject in that many of ...   Kirkus

12-07-11   It was 1978, (in sweden) and i just got my first job cooking ...   Peterr53

12-08-11   Peter53, will finding those old amps not just be an attempt ...   Lacee

12-08-11   I remember going from a dyna 416 to a david berning ea 150 t ...   Mpcrnc

12-09-11: Barrysandy
- Acoustic Research integrated with AR5s. Solid state sound hard and glarey. Gave SS a bad name (which it deserved)
- Dynaco ST 120 - more of the same!
- Crown IC 150 and D150 driving Infinity 2000As - World class speakers even today and beautiful looking pre and amp but op amps and boatloads of negative feedback = bleeding ears + empty wallet!
- Phase Linear 700B- Much better but still electronic
- Phase 400 - better still and actually nice with beefier power supply caps. driving T-1Ds (needed ARC!)
- Hafler 100 & DH200 - actually not bad and better pooged.

Barrysandy  (System | Threads | Answers | This Thread)

12-10-11   Hi lacee... you are most likely right about the "we le ...   Peterr53

12-12-11: Dividebytube
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.

Dividebytube  (Threads | Answers | This Thread)

12-14-11   Well, my flame linear blew up, as did my dyna 120. having wo ...   Fstein

03-21-12   I also work in the hi-fi business and have been fortunate en ...   Ajw_atlanta

03-21-12   i had a dyna stereo 120 which had substitute transistors an ...   Tbg

03-21-12   My system in 1976 would probably still sound pretty good by ...   Salectric

03-21-12   Salectric, your speakers sound like the fulton premiers whic ...   Tbg

03-21-12   Tbg, i would have loved to own a set of fulton j-modulars or ...   Salectric

03-22-12   Salectric, i must say that i heard them when fulton visited ...   Tbg

03-22-12   I liked the tandbergs. these were among the best i recall he ...   Mapman

03-22-12   I had a set of fulton j-modulars as well. for a long time i ...   Atmasphere

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