AR Amplifier Vintage Ad

[Guest linedrive]

Some good info on how the AR amplifier was spec'd:

http://www.classicspeakerpages.net/dc/user_files/1468.jpg

[tysontom]

This ad was conservative for the AR Amplifier: even though rated for only 60-watts-per-channel into 4 ohms, most of them would produce greater-than 90 watts -- at mid-frequencies -- into 4 ohms! In 1968, I took my early model AR amp to a local free McIntosh Amplifier Clinic and had them check the amp. David H. O'Brien, the McIntosh engineer who did most of the clinics, tested the amp for its full-rated power into 8 ohms, and the amp exceeded the McIntosh "miminum-distortion" limits, but he was reluctant to test it at higher output or lower impedance. After I asked him to test the amp at 4 ohms and 8 ohm at maximum power under 1% distortion, he did so, but would not graph it as it was not their practice to measure outside the "rated" power for any amplifier. The results are shown on the graph in Figure 1.

http://www.classicspeakerpages.net/dc/user_files/1469.jpg

Fig. 1 AR Amplifier performance at a McIntosh Clinic in 1968.

--Tom Tyson

[dynaco_dan]

Hi Tom;

Great information from you as always.

The rumour here in Vancouver, at that time, was, the Mc Clinic wouldn't test the AR amplifier because they would catch fire.

I never atended a Mc Clinic, so I can't verify that rumour.

There was a general rumour that they did catch fire.

Another rumour used by salespeople here was, that Sansui was called Mc south of the border.

Mc was a well respected name at that time.

I thought that, that one was really creative.

Lot's of rumours, but it is nice to finally read only the truth on this site.

Did you know that the AR turntable used a cheap clock motor and that you could go to a drugstore, to buy a replacement elastic drive band, was also used to cheapen the AR turntable quality.

Another amazing anti-AR sales pitch from that era.

The salesperson's didn't know that I was working at the AR warantee depot at that time.

This is one great web site for factual information, thank you, to all members.

[tysontom]

>

>The rumour here in Vancouver, at that time, was, the Mc Clinic

>wouldn't test the AR amplifier because they would catch fire.

>

Vern, I haven't specifically heard that "fire" rumor regarding AR Amps being tested at the McIntosh clinics, but it's certainly not improbable; I believe that McIntosh's Dave O'Brien was an honest, decent individual willing to test most anything, but I would not doubt that many dealers (who usually sponsored the clinics, but also sold competitive products such as Advent and KLH) were more than willing to disparage AR products. For example, the dealer that tested my AR Amp was one of the largest KLH dealers in my area at the time. I don't think that Dave O'Brien was particularly impressed with the AR Amp, despite the fact that it met or exceeded its specifications. I suspect that he was surprised that this little powerhouse could do as well as it did, but he did not think the amp was conservatively designed, and to an extent he was probably correct.

--Tom Tyson

[onplane]

There is no date on that ad. Any guesses when it might have been run?

Being ever curious, I just downloaded the service manual from the library to see what kind of animal the AR amp really is.

You probably don't want to hear this, but the AR amp is a fairly old design that was replaced by the "quasi-complementary", which Heath and others introduced in 1968-1969 time frame. You will see much lower distortion specs from quasi amps AND ... it's real!!

I actually had an EICO receiver with an amp similar in design to the AR. NOT to digress too much, but I wish I still had that EICO receiver. It was really unique as all the transistors were in sockets!! Yep, sockets! As you know, EICO produced a large number of tube amplifier kits (I had one of those as well - today that piece of junk is worth it's weight in gold! In all fairness, it was nice to have around on those bitter cold winter nights - amp kept you comfortably warm while the sound was just ... dreadful!).

But I digress, as I was saying EICO made a ton of tube kits and the tubes were always in sockets. So on their first venture into solid state, they put the transistors in ... of all things ... sockets! I mean you can literally keep that old amp running ... forever!

Now for the earlier comment on distortion ... both my old EICO and the AR amp have an interstage TRANSFORMER!!?? Now, having a transformer at low power is much, much better than at the output stage(like those blasted tube amps). Problem is the harmonics that transformers introduce. If you ever get a chance put a pure sine wave (from a signal generator) into a transformer and the look at the unloaded output. You just won't believe what you see. It looks nothing like a sine wave. Then if you load the transformer ... it only gets worse!

The "quasi" design eliminates transformers and instead uses diff amps to split the signal. Just by eliminating the transformer, you get a huge reduction in harmonic distortion.

I will say the EICO solid state was a very nice sounding amp especially compared to the EICO tube amp.

Regards,

Jerry

[Guest russwollman]

One thing I always noticed and admired was the honesty and simplicity in AR's advertising and presentation of their wares. I have never seen that ad for the AR amp—so remarkable for its time and doubly so in this age of unrelenting hype—but I remember very well the many ads for the speakers. So I wonder what sort of consciousness existed within the halls of AR. Perhaps you'd like to comment on that, Tom?

[dynaco_dan]

>>

>>The rumour here in Vancouver, at that time, was, the Mc

>Clinic

>>wouldn't test the AR amplifier because they would catch

>fire.

>>

>

>

>Vern, I haven't specifically heard that "fire" rumor

>regarding AR Amps being tested at the McIntosh clinics, but

>it's certainly not improbable; I believe that McIntosh's Dave

>O'Brien was an honest, decent individual willing to test most

>anything, but I would not doubt that many dealers (who usually

>sponsored the clinics, but also sold competitive products such

>as Advent and KLH) were more than willing to disparage AR

>products. For example, the dealer that tested my AR Amp was

>one of the largest KLH dealers in my area at the time. I

>don't think that Dave O'Brien was particularly impressed with

>the AR Amp, despite the fact that it met or exceeded its

>specifications. I suspect that he was surprised that this

>little powerhouse could do as well as it did, but he did not

>think the amp was conservatively designed, and to an extent he

>was probably correct.

>

>--Tom Tyson

>

>

Hi Tom;

That comment about catching fire, was not, I repeat not, from a Mc dealer or Mc rep at all, and I am positive on that.

It was a general non-Mc dealer, rather a salesperson's, comment to create doubt about buying an AR amp.

The Sansui is Mc south of the border, was spoken to me, as the salesman looked around to be sure there was no witnesses to that very creative comment.

That particular salesman, became even more creative, as time went along.

Later on, he would keep looking over his shoulder, but for a different reason.

How about a pair of AR-3A's, on a pair of speaker stands, up front and center, in a large high-end demo room.

The only problem that I saw, maybe some people would say I'm just too picky here, was, they both had non-functioning tweeters, for whatever reason.

Blown, wires cut or disconnected internally, not just dirty pots at least, I tested those out.

But, Tom, they still sounded awesomely beautiful and authoritive, nevertheless, less the tweeters.

I still get a rush just thinking of that demo, all these years later.

Similar crap was handed out by local salespeople, regarding Dynaco electronic products, as well.

With all the bad mouthing of AR and Dynaco, it was amazing that they did so well.

Can you imagine if every dealer had sold AR, but with a positive attitude.

I guess the truth wins out in the end.

From all of the honest members we have here, I will guess, if they had been AR dealers they would be, "honest, but poor", hifi dealers.

[Guest linedrive]

The advertisement is from the December, 1968 issue of Stereo Review.

[ninohernes]

I have an Eico HF-89, which is a 50 watt per channel class A push pull amplifier, and it sounds glorious. I have never heard a bad Eico tube product, with the exception of some of the later stuff. What model did you have?? My HF-89 produces undistored sine and square waves from around 4 Hz to 20 KHz at full output. It is rated at 50 watts per channel, but my tech measured it, and it produced around 65 watts per channel before clipping.

The Eico HF series of gear manufactured between 1955 and 1965 was really the best.

Also, I have run into many Eico units that were incorrectly assembled by the owners. This can cause the units to sound bad.

[tysontom]

>

>You probably don't want to hear this, but the AR amp is a

>fairly old design that was replaced by the

>"quasi-complementary", which Heath and others

>introduced in 1968-1969 time frame. You will see much lower

>distortion specs from quasi amps AND ... it's real!!

>

>

>Regards,

>Jerry

Jerry, hindsight is always 20-20! There can be no doubt that any number of amplifiers improved upon the AR Amplifier as time went by, especially *after* the AR Amp had been around for a few years. But no excuses need be made for the AR Amplifier. In October, 1967 -- and for several years thereafter -- NO amplifier made by any manufacturer could match the performance of the AR Amplifier at anything close to its $225 selling price. For that cost you had an amplifier that could produce well-over 60 watts-per-channel into 4 ohms at under 0.5% distortion, both channels driven, from 20-20K Hz. The amp could produce much more power than that, so it was very conservatively rated. The AR Amp was also unconditionally stable under any sort of load, especially low-impedance, highly capacitive-reactive loads -- something that many amplifiers could not handle. The “much lower” distortion to which you refer for the Eico and Heath amplifiers was neither realistic nor conservative on the part of the manufacturers; besides, please don’t tell me that you can detect one-tenth of one-percent harmonic distortion! Distortion lower than one-half of one percent is really meaningless, and the AR Amp never exceeds 0.5% at any rated-power level. Probably 99% of all humans can barely detect a one percent distortion, let alone tenths of a percent, so it’s a moot point.

The AR Amp was an outstanding performer, and it had a great preamplifier section as well. If it had a shortcoming, it was more “performance-based” than “durability based,” and some early AR amplifiers developed trouble (which AR usually repaired for free) after a few years. The bias circuit gave problems, and the result could be some wild variations in the dc offset, but these issues were resolved with the fixed-bias setting rather than the earlier variable control. Some amps did self-destruct as a result of this early issue, but most AR Amps worked flawlessly for many years.

--Tom Tyson

[dynaco_dan]

>>

>>You probably don't want to hear this, but the AR amp is a

>>fairly old design that was replaced by the

>>"quasi-complementary", which Heath and others

>>introduced in 1968-1969 time frame. You will see much

>lower

>>distortion specs from quasi amps AND ... it's real!!

>>

>>

>>Regards,

>>Jerry

>

>

>

>Jerry, hindsight is always 20-20! There can be no doubt that

>any number of amplifiers improved upon the AR Amplifier as

>time went by, especially *after* the AR Amp had been around

>for a few years. But no excuses need be made for the AR

>Amplifier. In October, 1967 -- and for several years

>thereafter -- NO amplifier made by any manufacturer could

>match the performance of the AR Amplifier at anything close to

>its $225 selling price. For that cost you had an amplifier

>that could produce well-over 60 watts-per-channel into 4 ohms

>at under 0.5% distortion, both channels driven, from 20-20K

>Hz. The amp could produce much more power than that, so it

>was very conservatively rated. The AR Amp was also

>unconditionally stable under any sort of load, especially

>low-impedance, highly capacitive-reactive loads -- something

>that many amplifiers could not handle. The “much lower”

>distortion to which you refer for the Eico and Heath

>amplifiers was neither realistic nor conservative on the part

>of the manufacturers; besides, please don’t tell me that you

>can detect one-tenth of one-percent harmonic distortion!

>Distortion lower than one-half of one percent is really

>meaningless, and the AR Amp never exceeds 0.5% at any

>rated-power level. Probably 99% of all humans can barely

>detect a one percent distortion, let alone tenths of a

>percent, so it’s a moot point.

>

>The AR Amp was an outstanding performer, and it had a great

>preamplifier section as well. If it had a shortcoming, it was

>more “performance-based” than “durability based,” and some

>early AR amplifiers developed trouble (which AR usually

>repaired for free) after a few years. The bias circuit gave

>problems, and the result could be some wild variations in the

>dc offset, but these issues were resolved with the fixed-bias

>setting rather than the earlier variable control. Some amps

>did self-destruct as a result of this early issue, but most AR

>Amps worked flawlessly for many years.

>

>--Tom Tyson

>

Excellent write-up as always, Tom.

I did not rave about the AR amp in my write-up at all.

The standby circuit, null control, outstanding bass and treble control performance and powerful amp is just the tip of the iceberg.

The amp stood out, but the pre-amp really was a beauty.

Un-fortunately I rarely used the bass and treble control and only tried the null once or twice.

I never needed to boost or decrease the treble or bass.

They were designed on the Fletcher-Munson curve, as I remember.

Rather unique in an integrated amp at the low price of $225.00.

Except for a slight light dim or flicker when turned on, there was no turn-on transient noise.

You had to turn the gain up quite high to hear any hum at all.

Whereas I rarely ever use the AR amp, it is only because I use the Crown and Dbl Dyna regularly.

Plain Jane, but well worth it.

A Dynaco 120 amp and a PAT-4 pre-amp was probably the closest in value.

[onplane]

Hi, Joe!

I believe (now it was a looong time ago) that I had the model ST-70. It looked very similar to:

http://home.netcarrier.com/~rstevens/st-40.html

Joe, you are correct about the assembly as I discovered a mistake in assembly after using for 3 months. A feedback loop on one channel went to an empty pin!!??

I discovered when doing a left/right comparison.

As for the sound, I was never satisfied with the low frequency range on the EICO. It had no depth and little power down low.

Regards,

Jerry

[ninohernes]

The Eico tube integrated amps are tube rectified. I never really cared for the ST-40 and ST-70, but the HF series of power amplifiers were fantastic.

I do agree with your observations about the ST-70, it is rather mushy sounding.

[onplane]

Hi, Tom!

Clearly the AR amp was a good value in terms of price and durability. The Dynaco unit that Vern referenced (120) was introduced in 1966 at a kit cost of $208.

In terms of performance, the specs were similar 60 watts into 8 ohms, 0.5% THD

Now, the Dynaco unit had no "interstage" transformer which will alter the resulting sound (Dynaco was a "quasi" amp).

It had a serious drawback, however, you CANNOT passively bi-amp the AR-3, AR-2ax or the AR-3a with the Dynaco unit. You can, however, with the AR amp! In fact, given that the AR amp has 20% less reserve than my Heath AR1500, I'd recommend giving passive bi-amping a try.

As for those blasted bias circuits, now only are they troublesome for the amp, but they can create havoc with the speakers as well! This is especially true of a direct coupled amp, like the AR. Even a small DC offset can alter the performance of a speaker.

Regards,

Jerry

[Guest Eunomians]

I'm a little late to the party, but what a fascinating thread nonetheless.

It does not surpise me that folks would ridicule 'other' brands. It seems to me that these sort of practices are rampant in the audio realm, as well as with most all other facets of consumerism.

Is this annoying?

Well, every time I have stepped in to a hi-end audio store or a speaker/equipement repair shop as of late, I have heard disparaging comments about this or that brand. There was a time were I enjoyed talking with folks about different gear and gear combinations, but no more. I keep to myself and instead enjoy reading thoughts, opinions and sentiments online.

I'll answer my own question: Yes.

For now, I'm real glad that I have a spicy mexican Sansui 9090.

One day I will have a Bunsen-Burner vintage AR amplifier, and perhaps a Mcintdonald's Happy Meal Combo.

[onplane]

No, Noooo!!

Please don't misunderstand. I am NOT ridiculing the Dynaco unit. To the contrary, by eliminating the inter-stage transform Dynaco achieves superior results in terms of harmonic distortion.

It does, however, have a slightly unusual quirk and that is the speaker outputs are NOT common grounded. Nothing wrong with that for 99.999999% of the speakers. It’s just that, if you wanted to passively bi-amp the early AR’s (those with 3 terminals), you can NOT do it with the Dynaco unit WITHOUT opening the sealed boxes.

Sorry, I wasn’t being very clear. The Dynaco 120 is a good amp and the only real competition for the AR amp back then.

Regards,

Jerry

[ninohernes]

>It does not surpise me that folks would ridicule 'other'

>brands. It seems to me that these sort of practices are

>rampant in the audio realm, as well as with most all other

>facets of consumerism.

After all this is basically an AR "fan page".

However, it is important to keep an open mind. I spend a lot of time in hifi shops auditioning gear as part of my job. I am always on the lookout for great sounding affordable components. I will say that trying to find an affordable (sub $2000 a pair) bookshelf speaker that beats the AR-3 or 3a is very difficult. There are many that come close, but no cigar! They either seem to get the high end correct, and the low end is lousy and vise-versa. The AR-3 and 3a seem to be just right.

Are there speakers better than the AR-3 series? Sure, for example the Venture CR-8 Signature. But they are well over $40,000 a pair. In my experience you cant find a speaker under $2000 a pair that beats the 3 series. Many argue this, and I respect their opinion. If everyone had the same opinion, we would never progress!

Anyway, sorry for going off topic.

[Guest Eunomians]

You are right about keeping an open mind - thanks for your posting your thoughts.

Well, back to the issue at hand.

Very interesting ad. Another reminder for me, as I have been yearning to own an AR amplifier. I have been outbid numerous times and consequently, I have sorta given up (for the time being). I am most curious about how they sound, how the knobs feel whilst turning them, etc...

Most importantly though, I am very curious how they would sound paired up with my AR3a's!

-Best regards

[onplane]

What are you using to drive your AR-3a's today?

I am currently using my old AR1500 (HeathKit) receiver for the woofer. AR1500 is rated conservatively at 100 watts rms per channel at 4 ohms.

Mid-range and Tweeter are driven by an old Pioneer AV amp rated at 30 watts per channel "music power" - what ever the heck that is.

Regards,

Jerry

[Guest Eunomians]

For me, it's my spicy Sansui 9090.

I've got the 3a's running with a Dynaco QD1 Quadaptor with Minimus 7's in the Hafler circuit.

The 9090 really opens up the AR3a's. Sounds so sweet in our living room. I think that I have finally found the perfect setup for this house/room. The best part is zero fatigue. The bad part is that I can't always be home to listen to this setup

I'd sure love to try one of the AR amps once day...

[dynaco_dan]

>

>I'd sure love to try one of the AR amps once day...

Hi there;

The controls on my AR amp are as follows, feel not function.

Selector switch, smooth, positive detents, a feel of quality.

Bass and treble controls are ganged and feel silky smooth, I don't use them, but they are worthy of using, feels like they are loaded with a silicone compound.

They also have very good circuit characteristics, if you use them.

Balance control, nothing special to say, and the null switch, likewise.

On - off switch/volume control, positive on/off function and silky smooth volume resistance.

The brushed gold faceplate and lettering stands up pretty well to body sweat.

The knobs are very slightly grooved and perspiration does take its toll on the finish, hardley noticeable.

If the amp had come with fine dress gloves, it would still look like new.

Good luck.

[Guest Eunomians]

Ahhh, just what I would've imagined... Quality superior construction. Now I am really craving one of these darlings.

Once again, thanks for your time, Vern!

Best regards

[ar_pro]

Your 9090 is giving you a really "fat" sound with the 3a's - the big Sansui & Marantz receivers were always a nice match with AR speakers, emphasizing that great acoustic-suspension low-end.

I'd characterize the AR amplifier as having had a more "polite" sound than your Sansui - not that it wouldn't play loudly, it just seemed a tad more refined and at home with acoustic, as opposed to electronically-enhanced music.

That said, I loved the AR amplifier, matched to the 2ax and 3a systems, with everything from Coltrane to Zeppelin.

I've also heard the Dynaco PAT-4/ST-120 combination many times, and believe that the AR amplifier is the better choice - especially for the 3a, and it's low, low impedance.

Be forwarned that there are a number of hard-to-find capacitors in the AR amplifier that will need to be replaced, and the adjustable-bias fixes must be employed for best results. And don't leave it plugged in, and go on vacation!

[tysontom]

>Hi, Tom!

>

>Clearly the AR amp was a good value in terms of price and

>durability. The Dynaco unit that Vern referenced (120) was

>introduced in 1966 at a kit cost of $208.

>

>In terms of performance, the specs were similar 60 watts into

>8 ohms, 0.5% THD

>

>Now, the Dynaco unit had no "interstage" transformer

>which will alter the resulting sound (Dynaco was a

>"quasi" amp).

>

>It had a serious drawback, however, you CANNOT passively

>bi-amp the AR-3, AR-2ax or the AR-3a with the Dynaco unit.

>You can, however, with the AR amp! In fact, given that the AR

>amp has 20% less reserve than my Heath AR1500, I'd recommend

>giving passive bi-amping a try.

>

>As for those blasted bias circuits, now only are they

>troublesome for the amp, but they can create havoc with the

>speakers as well! This is especially true of a direct coupled

>amp, like the AR. Even a small DC offset can alter the

>performance of a speaker.

>

>Regards,

>Jerry

>

The Dynaco Stereo 120 was a reasonably good amp, but not particularly suited to low impedances. I never felt it could drive four ohms as well as the old Mark III. The 120 was rated at 60-watts/ch into 8 ohms, but it would not do as much into 4 ohms if I recall. I had one for a couple years driving my AR-3s (and later AR-3as), and it just didn’t have the punch of the AR Amp. Into 8 ohms -- such as the AR-2ax or AR-5 -- it was great, however. The Stereo 120 also had very little “headroom,” whereas the AR Amplifier has lots of reserve. My Stereo 120 always ran hot driving my AR-3s and later the AR-3as, and it eventually failed with burn-out output transistors. That was it: I got rid of it and never looked back.

What do you mean that the inter-stage transformer will “alter the resulting sound?” Do you mean that there is an audible distortion or anomaly in the sound of the AR Amp? I’ve never heard that one. The AR bias circuits (variable-resistor at first, fixed-resistor later on) could cause trouble, but only if the circuits were way out of spec. A small dc offset is not audible; just about any direct-coupled amplifier will have a little offset, and it can’t be heard unless there is noise in the output anyway. It has very little effect on a speaker. Unless the offset is in “volts,” rather than “millivolts,” the speaker won’t be bothered by it. The offset is usually in millivolts anyway.

As we said before, bi-amping a single-ground AR crossover is not a prudent thing to do. Using a passive crossover, you do not benefit from active crossover *before* the amp, so the only potential gain is more power and lower distortion. It’s easier, and far safer, to merely use a more powerful amplifier. Bi-amping, as you describe, using the single AR #1 terminal as a ground point, will one day bring down your house of cards, so be careful! Always turn off your equipment when you are not in the same room, that sort of thing.... The end result might be instability or eventual overheating, or both. Incidentally, AR warned dealers against doing this sort of thing, but only for the reasons of there being no logical improvement in performance. AR specifically advised against ever by-passing the crossover to utilize electronic crossovers, mainly because the network helps to “shape” the frequency response of the speakers to some extent. So, either way you slice it, bi-amping is a “no-no.”

--Tom Tyson

[dynaco_dan]

>Ahhh, just what I would've imagined... Quality superior

>construction. Now I am really craving one of these darlings.

>

>Once again, thanks for your time, Vern!

>

>Best regards

Hi there;

You are very welcome.

I just can't leave you hankering for an AR amplifier, now.

When my amp was still under warantee, I wrote to Roy F Allison and he sent me a kit of parts with the schematics for doing the bias repair job.

I downloaded the schematics to this site, somewhere, a few years ago.

I am certain, I could locate them with a google search.

That was the original drawings from AR at that time.

Each amplifier was built individually, at least at the end of the assembly line.

The driver transistors, as I remember, were colour coded and the colour codes were different in all of the amps, making for different resistor values for the bias repair.

The drawings and instructions were very clear.

Serial number ranges were used as well, for the amp and receiver.

The only concern I would have would be, to have the front scratched by a rough serviceperson, it is only anodized aluminum.

It is not difficult, with only your fingers or rubber gloves, to pull firmly, the knobs straight off, remove the lock nuts and the face plate slides right off.

Some might say the amp is dated, it is bringing in about the original retail prices, now on ebay.

I still do remember the initial thrill of owning one, what a rush.

The same as when I first laid my eyes on my AR tuner, AR turntable and first pair of AR-4X's.

Did I say I like AR?

As far as the tuner goes, I had the amp and wrote to Roy F Allison and asked him if they were going to make a tuner.

He replied, well in advance of the official launching, a very positive, yes.

From then on, I just waited, disregarding Heathkit's top AJ-15 tuner and any others for about another 6 months.

There is so many things that I would liked to have thanked Roy F Allison for.

Thank you Roy, for all your contributions to our enjoyment.