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AR 9 Power ?


Rat44

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I am concerned about the 4 ohm rating of the 9's.

Ive heard that the SX series was not happy running 4 ohm loads.

I have been using it with a set of early ADS L-810's and that has been a good match.

Just don't want to cause unnecessary damage to the receiver or speakers.

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Hello Rat44-welcome to the club. I have had my AR9's for over 30 years-I will give you two quotes, from the original AR9 reference manual, that delineate power handling areas:

"amplifier power requirements-50 watt minimum is recommended. 50watts (into one speaker only) will produce 104db SPL in a 3000 cu.ft. room of average reflectivity (energy absorption coefficient of 0.15)"

"power handling capability-may be used with amplifiers capable of delivering 400 watts continuous power per channel being driven to clipping 10 percent of the time on normal music source material. This statement of power handling is based on the use of contemporary amplifiers of good design, stable operation and instantaneous recovery from overload and which are able to deliver very-short-duration peaks of approximately 2.5 times their rated continuous power into the normal reactive, 4 ohm load of the loudspeaker."

I drive my 9's with at 200 watts per channel, into 4 ohms, with 1.5 db headroom. I would check, as much as you can, that your receiver, or receivers, have some technical documention, concerning driving 4ohm reactive loads-hope the above information helps, rather than confuses your questions--9's can handle some power, and 4ohm loads can "stress" some receivers and amplifiers. Good listening to you

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I know this may annoy folks but as an audiophile of that era...Japanese amplifiers/receivers were not considered particularly good. They were widely available and used because of the large number of servicemen/women who served in Vietnam era and the PXs (here and overseas) carried mostly japanese products of that type and the few American products carried were considerably more expensive.

A suitable amp for LSTs from back then would have been something like one of the Phase Linears, a McIntosh, Crown, etc. The serious AR crowd (of which I was one) would never have powered a 3A or an LST with a Japanese amp. Tests from back in the day repeatedly demonstrated their lack of capability compared to the (more expensive) US amps and the common use of IHF power ratings instead of RMS.

I am referring to amps made in the AR era - call it from around 1960 to say 1980 - I am not referring to Japanese amps that came later.

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I know this may annoy folks but as an audiophile of that era...Japanese amplifiers/receivers were not considered particularly good. They were widely available and used because of the large number of servicemen/women who served in Vietnam era and the PXs (here and overseas) carried mostly japanese products of that type and the few American products carried were considerably more expensive.

A suitable amp for LSTs from back then would have been something like one of the Phase Linears, a McIntosh, Crown, etc. The serious AR crowd (of which I was one) would never have powered a 3A or an LST with a Japanese amp. Tests from back in the day repeatedly demonstrated their lack of capability compared to the (more expensive) US amps and the common use of IHF power ratings instead of RMS.

I am referring to amps made in the AR era - call it from around 1960 to say 1980 - I am not referring to Japanese amps that came later.

I am aware that most Japanese amps could not power difficult loads properly.

I used Phase Linear 400's with my AR 10pi's back then.(I was a GI in the 70's)

I have not been able to find out much on the 4 ohm capability of the 1250.

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I am aware that most Japanese amps could not power difficult loads properly.

I used Phase Linear 400's with my AR 10pi's back then.(I was a GI in the 70's)

I have not been able to find out much on the 4 ohm capability of the 1250.

Correct me if my memory is mistaken--but I was under the impression that the 1970's-era Japanese integrateds from Kenwood, Pioneer, Sansui et al were solid performers and well-matched to the demands of driving AR speakers, including 3a's. I had a Kenwood KA-7002 in the summer of 1972 and used it very successfully to drive my cousin's 3a's that he lent me for the summer. He used a Sansui (I think it was the AU-999--is that a correct model number?) with his 3a's. I later had a Kenwood KA-8100 which drove the bejeebers out of the LST-2's I acquired in 1980.

On the web, many people sing the praises of other Kenwoods (like the 9100) and Pioneers/Sansui's of that time.

True, they didn't have the pure muscle or headroom of a PL400 or 700, but based on my experiences and the experiences of others, I thought we all regarded them as fine medium-powered matches for 1970's ARs, including the 3a.

Or am I remembering incorrectly?

Steve F.

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As I said earlier, a LOT of them were sold - frequently bundled with speakers of the same brand. They were fine for what they were but they were nowhere near the capability or the stability of the US-made amplifiers in the 100+WPC range AT THAT TIME.

I blew out tweeters on AR 2AXs and AR3As back in the day with amps like the Sansui and Pioneer amps due to insufficient RMS power (all totally covered by AR's superb 5 year warranty). Never blew another tweeter after switching to a PL400 in 1972.

Obviously, if you listen at moderate levels it's not really an issue. My 3As at comfortable background music level drew around 3 WPC. BUT if you put a recording like the Telarc 1812 Overture recording and set the volume at the beginning at a comfortable listening level, the cannon shots at the end will cause my 270WPC McIntosh amp to activate it's "Powerguard" anti-clipping circuit. And the cannon shots are not ALL THAT LOUD. Once an amp goes into clipping, it can fry tweeters quite quickly.

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As I said earlier, a LOT of them were sold - frequently bundled with speakers of the same brand. They were fine for what they were but they were nowhere near the capability or the stability of the US-made amplifiers in the 100+WPC range AT THAT TIME.

I blew out tweeters on AR 2AXs and AR3As back in the day with amps like the Sansui and Pioneer amps due to insufficient RMS power (all totally covered by AR's superb 5 year warranty). Never blew another tweeter after switching to a PL400 in 1972.

Obviously, if you listen at moderate levels it's not really an issue. My 3As at comfortable background music level drew around 3 WPC. BUT if you put a recording like the Telarc 1812 Overture recording and set the volume at the beginning at a comfortable listening level, the cannon shots at the end will cause my 270WPC McIntosh amp to activate it's "Powerguard" anti-clipping circuit. And the cannon shots are not ALL THAT LOUD. Once an amp goes into clipping, it can fry tweeters quite quickly.

We're talking about apples and oranges here. The implication in an earlier post was that 1970's Japanese amps were unstable into low-impedance loads, like 3a's.

That was not my experience. The better integrated amps from K, P, and S were solid into 3a-type loads, based on my experiences and those of my friends/relatives. My Dad and a cousin both had a 120 WPC Sanyo receiver that was built like the perverbial battleship and drove my cousin's 3a's in its sleep.

The point you're bringing up is not instability into low-Z loads, but clipping due to insufficient power to achieve a desired SPL. That's a perfectly valid issue, but it's not the instability issue.

The original statement was that 1970's Japanese amps were not great with low-impedance loads. My point is that I don't seem to recall that, at least with the better integrated amps. The receivers may have been a different story, but they usually used essentially the same amp design and layout.

Instability into low-Z loads and clipping due to insufficient power are two different issues.

Steve F.

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I did not suggest they were unstable; they were fine if used within their limits. It's just that in general their actual RMS power limits (as opposed to their advertised IHF ratings) were well below what AR3As were (are) at their best with. I still recall testing one of the Sansui's - I can't recall the model number - that was rated at 120WPC but when tested at Bill Case Sound in San Antonio, TX, it was putting out around 50WPC RMS.

OTOH, I would assume that if they had amps in the 300wpc IHF category, one would assume they could manage at least 100 WPC RMS and they would probably be fine with 3As.

But it's important to remember that 3As (and 2Axs) were well known for tweeters burning out when driven hard. We thought they were fragile but we learned later that the bigger the amp, the less likely you were to damage a tweeter because there was sufficient power to avoid going into clipping and clipping is what burnt out the tweeters.

IMO, if you want to drive an AR3A to the kind of listening levels it was designed to produce in a decent sized listening room, 200WPC RMS (or more) is a good place to be. But if you are just going to listen to it for general pop music at background or slightly higher levels, you could probably get by with 20WPC. As I said earlier, the power meters on my McIntosh amp seldom got above 3WPC with the 3As when used that way.

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Some very interesting viewpoints being presented here.

I also have a pair of AR 2ax's that need to be restored so some of this is also applicable.

In the past I have had good luck using the Pioneers as my main source but I have never tried to power low ohm speakers.

The Phase Linears 400's that I have used were very good at what I was using them for,never had a problem driving AR 10pi's,Bose 901's,K horns or Cornwalls.

I have seen people using Crown and Adcom amps with AR 9's with good results.

I am just concerned with damaging the speakers with an inadequate amp.

A Pioneer SX 980 is presently powering the 9's now since my 1250 is going to my tech for a tuneup.

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I did not suggest they were unstable; they were fine if used within their limits. It's just that in general their actual RMS power limits (as opposed to their advertised IHF ratings) were well below what AR3As were (are) at their best with. I still recall testing one of the Sansui's - I can't recall the model number - that was rated at 120WPC but when tested at Bill Case Sound in San Antonio, TX, it was putting out around 50WPC RMS.

OTOH, I would assume that if they had amps in the 300wpc IHF category, one would assume they could manage at least 100 WPC RMS and they would probably be fine with 3As.

But it's important to remember that 3As (and 2Axs) were well known for tweeters burning out when driven hard. We thought they were fragile but we learned later that the bigger the amp, the less likely you were to damage a tweeter because there was sufficient power to avoid going into clipping and clipping is what burnt out the tweeters.

IMO, if you want to drive an AR3A to the kind of listening levels it was designed to produce in a decent sized listening room, 200WPC RMS (or more) is a good place to be. But if you are just going to listen to it for general pop music at background or slightly higher levels, you could probably get by with 20WPC. As I said earlier, the power meters on my McIntosh amp seldom got above 3WPC with the 3As when used that way.

No disagreement with anything said here.

One point of clarification/historical accuracy, however:

In 1974, the FTC implemented its power ratings regulation, which specified that all amplifier manufacturers must state a continuous ("RMS") power rating per channel, both channels driven, over a specified bandwidth at a specified level of distortion. Most amp manufacturers took this to mean 20-20kHz, at <.5% THD, although some--like Mac and a few others-- made a big deal about specifying at .25% or .1%.

That was a great regulation, and it absolutely did away with all the bogus IHF, Music, and Peak Power ratings that came before. None of the great Kenwood, Pioneer, Sansui, etc. amps were rated at IHF. They were all rated at RMS, both ch driven, 20-20, x% THD. My Kenwood KA-7002 was rated at 50 RMS per @.5% 20-20. Julian Hirsch found it to do 63 per, 20-20 @.17%. That was a typical result of the better Japanese integrateds and receivers of those days. I have lots of old back issues of Stereo Review and the High Fidelity Test Reports compendium from 1973, 1975, and 1980, and can send out any number of test reports that corroborate that point. I am not aware of a Sansui amp that was rated at 120 but really put out only 50. It's possible, I suppose, but that certainly wasn't the design--or competitive--norm in those days.

To sum up:

1. Yes, I agree that larger amps that don't clip are well-suited to driving AR speakers to satisfying levels in large rooms (even though Ken has written extensively and authoritatively on this Forum that the HF distortion products are too low in level to do the damage--he feels it's the actual drive level, not the distortion product itself that burns out those old AR tweeters. Disagree? Take that up with him, not me.)

2. The Japanese integrated amps of the '70's were quite good, usually exceeded their rated power and distortion specs, and were generally stable into low-Z loads.

Steve F.

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In reality it's probably not much of an issue because I suspect that most folks don't drive these 40+ year old speakers the way we (or at least some of us) did when they were new. For one thing, most folks don't listen to music in the same way we did back then. We used to get together JUST to crank up the volume to "realistic" levels and sit and listen to a new album (or two) by whoever. I don't think that happens much now. And, of course, I'm sure some folks don't care to drive them to those levels just because of their age.

99% of the time they are on, my LSTs are probably hardly aware they are producing any sound - they mostly just get the input from the computer and Itunes and provide background music. On rare occasions I'll put a CD on the CD player and crank it up a bit and on even rarer occasions, I'll put on some vinyl and listen like we used to. On those days, the LSTs and the McIntosh power amp get to do what they really can do but I'll bet I don't do that 10 times a year.

My 3A's are now the TV's external speakers, powered by an AR amp. So, they don't get worked very hard at all either.

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When I said a Sansui rated at 120WPC that was tested as around 50 RMS, the 120 WPC rating was listed as IHF. I don't think that they listed RMS at all but perhaps they did and I don't recall it. This was in 1970. As you noted, for sure they did later, as required by US law. In fact, the legislation requiring an RMS spec was a direct result of the influx of Japanese equipment during the Vietnam era using the IHF rating which made those amps appear more powerful - and therefore a better cost per watt deal - than US amps.

Prior to that time, the only separate amplifiers around in the US were from fairly well-known US manufacturers and "Continuous power" ratings were part of their specs so there really wasn't an issue. Typically, the wording was something like "100 WPC IHF music power or 50WPC continuous." What used to be called "continuous" evolved into "RMS" though personally I think "continuous power" is actually a more meaningful term in real life.

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When I said a Sansui rated at 120WPC that was tested as around 50 RMS, the 120 WPC rating was listed as IHF. I don't think that they listed RMS at all but perhaps they did and I don't recall it. This was in 1970. As you noted, for sure they did later, as required by US law. In fact, the legislation requiring an RMS spec was a direct result of the influx of Japanese equipment during the Vietnam era using the IHF rating which made those amps appear more powerful - and therefore a better cost per watt deal - than US amps.

Prior to that time, the only separate amplifiers around in the US were from fairly well-known US manufacturers and "Continuous power" ratings were part of their specs so there really wasn't an issue. Typically, the wording was something like "100 WPC IHF music power or 50WPC continuous." What used to be called "continuous" evolved into "RMS" though personally I think "continuous power" is actually a more meaningful term in real life.

Hi there

I had owned a Japanese receiver back in the sixties.

Very nicely made and very clean layout.

At least the resistors were not standing on end and the individual parts and wiring layout was first class, nothing less.

I also saw some real shabby designed equipment at the rock bottom hifi level that could be called, embarrassly, hifi equipment.

Definitely inadequate power and inflated specs though.

I cannot comment on the sound quality, too long ago and I really wasn't interested in anything other than listeninbg loud, real loud to CCR,

Chicago, Simon and Garfunkel (Cecelia), etc etc.

Back then an imported and possibly local amplifiers and receivers might have suggested in an ad, that there was, WOW!!!! 400+ watts.

It finally was broken down to somewhere about 10 - 20 watts per channel, if that on a good day, at 1,000 hz and 5% distortion, with only one channel running sometimes.

I guess there was so much public or American manufacturers concern and outcry that the government stepped in and the FTC held meetings to

arrive at a universaly acceptable standard for amplifier power output.

I sent my ideas in at that time, 1974+/-, to the FTC and they sent me a letter thanking me for my input and said they would let me know of the outcome.

I was mailed a free copy of their, regulation statement manual, 38 pages long, printed on both sides of each page.

I doubt I ever read it, but do have it onhand as I type this.

This was now a rock hard standard, or so it was thought, apparently, according to AVA.com older newsletters.

There was some loopholes or such which allowed some manufacturers to still, exaggerate or bend the rules slightly, if I remember right.

The Dynaco 400, was, from his memory, the only amplifier that passed their new standard, first time around.

Crown, if you have an owners amplifier manual, or download one from their site, from around that time period, did not include certain graphic information in their amplifier manuals.

Dynaco derated their amplifiers after the ruling rather than come out with all new model amplifiers.

Apparently some offshore equipment was re-badged or re-designed and their new manuals would reflect a new model at the then acceptable standard, instead of just

having new manuals printed with deflated figures.

I have read many times over the years that we are in error using, for example, the term RMS power, in this context.

When we describe the AR amplifier's, 60 watts RMS @ 4 ohm capabilities @ .25%? distortion from 20 - 20,000 hz, the same description using the word, continuous, would probably

be more precise and accurate descriptor.

Even though there were reviews of the amplifier outputing about 110 watts per channel at 1,000 hz one channel driven.

Sine wave might be another choice for correct wording, I am not positive about that though.

Just a thought for today.

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The Institute of High Fidelity was an industry consortium with its offices at around 41st street and 5th avenue in NYC not far from Grand Central Station. In the 1960s I spoke with a vice president of the IHF and asked him about his clugey measurements. He didn't deny it, he just said it was designed to keep (expletive deleted) like Panasonic out. In those days, the early to mid 1960s, most Japanese electronics were pretty awful. That changed by the late 1960s or early 1970s when they started producing high quality amplifers and receivers. Companies like Accuphase were highly respected. Japanese also produced high quality consumer tape recorders early on. American Concertone became TEAC and Roberts became AKAI.

The IHF system for measuring amplifiers was widely used among many if not most US stereo component manufacturers. This method used the peak of the sine wave at clipping to falsely inflate power ratings by about 20%. It also allowed the measurements to be made with power supplies that were of the same voltage but of much better quality than those supplied with the amplifiers when you purchased them. No bandwidth or preconditioning requirements either. Companies like HH Scott, Fisher, Sherwood, Bogen, Pilot, HK (except Citation) Lafayette Radio all used them. Some would give the RMS ratings as well, some wouldn't. Dynaco, MacIntosh, Marantz, Crown, and AR were among the few who only used RMS ratings. But the 3 top consumer review magazines gave the true ratings in all their test reports.

The console mass market specs were even more outrageous. EIA standards allowed 5% THD, in other words well into clipping. As the horsepower numbers game escalated, some EIA manufacturers even reportedly used the power consumption, that is the AC power input as their rating. A 15wpc RMS amp might be called a 240 watt amplifier.

RMS and continuous power are synonymous. This takes into account the equivalent area under the sine curve, in other words its average or DC equivalent voltage and current measured one frequency at a time. The FTC rating system requires among other things that the amplifier be preconditioned for 20 minutes at 1/3 its rated power before measurements are made. For this reason, the Dynaco 80, 80Q, SCA80, and SCA80Q all having power amplifiers identical to the Stereo 120 with the exception of using an unregulated power supply had to be derated from 40 wpc RMS to 30 wpc RMS.

I have a Pioneer 950 receiver in near mint condition I bought at a garage sale for $10. It is an excellent unit I think about 80wpc. I've used it to power AR2ax, KLH Model 6 and Empire 9000. It has performed very well with all of them. I expect it would do well with AR9 but I've never tried it and have no intention of trying it. What is required to power AR9 is at least 50 to 60 wpc with bandwidth to 20 hz and very high stability at 4 ohms or less. Many high quality amplifiers and receivers made in the US and Japan in the 1970s and 1980s meet those criteria. Most HT receivers made today don't, they are unstable at low impedence and will shut down to protect themselves. A sherwood receiver I have shut down on AR9s at modest volume even with the woofers disconnected. I use a Klaus/Peterson 120 watt MOSFET amplifier (60wpc) built from a kit for $200 in 1993 and it works very well in my 4000 cubic foot 400 square foot liver than average room. It produces excellent sound across the entire frequency spectrum down to the lowest bass without problems or complaints even in excess of 100db. This includes the deepest organ pedal tones. More power will only likely be needed in larger rooms for the deepest bass at very loud levels, well in excess of 100 db. Pioneer 1250 is one of the best receivers made and should perform excellently with AR9 IMO.

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