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Amp power for AR-3 speakers


Guest stankline

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Guest stankline

I have a pair of AR-3 speakers that were part of a stereo component system I purchased around 1968. (Including an AR turntable and Electrovoice 50 watt receiver). Currently, I am converting my vinyls and tapes to CD's. I want to purchase a new amp and CD player.

My question is how much amp power will the AR-3's tolerate? I appoligize in advance if this is a dumb question but I am not an audiophile.

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Guest postjob62

Stan,

I have struggled with this same conumdrum myself as regards 3a's, which I would think to have similar power appetites. The bottom line is, like most things, it depends; how big is your room, what do you listen to and how loud do you like it, and so on. Do a search on this site with various keywords that describe this topic and you will find a wealth of information. Many of the opinions will vary considerably, but if there were to be a consensus it would probably be around 100 wpc. Remember you are looking for a 4 ohm rating here.

You will find folks who drive older 12" woofer AR's with tremendous amounts of power (judiciously?) but I recall one fellow on this forum telling me he used an old Pioneer receiver successfully at around 27 wpc or so. I myself have used old Marantz receivers with around 30 wpc in a 18x19x7.5 room and it sounded great, but have recently hooked up a 200 wpc Adcom and must admit it sounds even better.

You must also decide which side of the old "is it distortion or just too much power/volume that kills tweeters" arguement you come down on. I myself would like to see more comments on that one.

In any event, there are many very knowledgeable folks here who will offer their advice-but do be sure to read all the archived posts you can find.

Ed

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>Stan,

>

>I have struggled with this same conumdrum myself as regards

>3a's, which I would think to have similar power appetites. The

>bottom line is, like most things, it depends; how big is your

>room, what do you listen to and how loud do you like it, and

>so on. Do a search on this site with various keywords that

>describe this topic and you will find a wealth of information.

>Many of the opinions will vary considerably, but if there were

>to be a consensus it would probably be around 100 wpc.

>Remember you are looking for a 4 ohm rating here.

>

>You will find folks who drive older 12" woofer AR's with

>tremendous amounts of power (judiciously?) but I recall one

>fellow on this forum telling me he used an old Pioneer

>receiver successfully at around 27 wpc or so. I myself have

>used old Marantz receivers with around 30 wpc in a 18x19x7.5

>room and it sounded great, but have recently hooked up a 200

>wpc Adcom and must admit it sounds even better.

>

>You must also decide which side of the old "is it distortion

>or just too much power/volume that kills tweeters" arguement

>you come down on. I myself would like to see more comments on

>that one.

>

>In any event, there are many very knowledgeable folks here who

>will offer their advice-but do be sure to read all the

>archived posts you can find.

>

>Ed

Hi Stan;

Congratulations on you good taste.

You are an audiophile since 1968.

Whatever caused you to buy AR-3's and AR turntable gives you the title of audiophile.

Only a small number of people would appreciate their stark appearance and superior performance at that time.

Remembering that the speakers are over 35 years old gives some cause for care in not overloading them.

The AR library has several fusing sheets and several topics have been discussed regarding fusing and power handling.

Whereas the slow blow fuses mentioned were considered sufficient when the speakers were new, a little downsizing may be in order.

They also are more difficult and expensive to buy now.

AR recommended amplifiers at 25 watts RMS per speaker in a typical room.

A 250 watt amplifier would not be out of line, with some qualifications.

If for example, an AR amplifier was being used, on, is at the 7 o'clock position and maximum is about 5 o'clock.

In between is a large range of volume change, but if 2 o'clock is too low of a volume for you then a larger amp may be needed.

Voice, classical music and some other sounds require less power than, say a kettle drum at very loud volume.

If your needs are basicly just sitting and enjoying the music and being able to talk to someone in the same room then your needs are lower.

Tube versus solid state is an issue I won't get into, but generally tube amps do not produce the best, deepest, tightest, bass.

I am sure there is still many listeners who have maybe 25 watts per channel equipment and do not overload the amps or speakers with just basicly background music.

Crownaudio.com web site has an interesting outlook on speaker fusing and it is another view of speaker safety.

They seem to lean towards a slow blow fuse for the woofers and fast blow for the higher ranges.

They also feel if you normal listening level is 85 db then a 150 watts per channel amp may be in order.

At 95 db a 1500 watts per channel amp may be needed.

I believe firmly in fuses, but trying to arrive at a perfect fuse size, sort of one size fits all category isn't at hand yet.

The AR-3 speaker is rated at 4 ohms but that is at the usual 1,000 hz only.

From the deepest bass, where the impedance may droop down to 30 - 40 ohms up to 15,000 hz where the impedance may again be 4 ohms.

The need for power is much greater in the woofers response than either of the other two drivers.

An amplifier usually produces more power at 4 ohms than at 16 ohms.

At 30 - 40 ohms you will still need 25 watts per channel or more.

You will receive many well thought out ideas from other members as they read your topic.

Good luck with your choices.

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There is no one right answer. The requirement depends on how loud they have to play, the size and acoustics of the room, the distance you will listen to them from, and the types and contents of recordings you will be playing. AR3a used the same cabinet and woofer as AR3 (the only things they had in common) but the woofer requirements defined the overall power requirements because that is where a speaker system is usually most demanding so what was true in this regard for AR3 is true for AR3a. AR recommended 25 watts RMS per channel amplifier for AR3 as a minimum. In 1960, this was a fairly large and expensive investment and beyond all but the most expensive amplifiers and receivers. Today, it is considered very small. In most rooms, and under most conditions, I think a 100 wpc amplifier would be a good choice. It's not a hard and fast number and the difference between a 75 wpc amplfier and a 150 wpc amplifer is usually rather a small difference all other things being equal. (a 2:1 power ratio is a difference of 3db which is only a minor difference in perceived loudness.) Most important is an amplifier's ability to deliver its rated power with low distortion at very low impedences and at low frequencies. This usually means a hefty power supply. A 9 wpc SET tube amplifier won't cut it and neither will a Sonic Impact T-amp. This also lets out all of those inexpensive 100 wpc Japanese A/V receivers which warn not to use with speakers below 8 ohms. AR3a can get to the 1 ohm range at some frequencies (we blew up a 60 wpc Scott receiver with a pair of AR3s for this reason.) The AR amplifier designed to offer a low cost high quality way to power a pair of AR3a s was rated at 60 wpc into 4 ohms but actually produced around 90. There are many fine amplifiers and receivers even available used at low cost which will do very well. I'm sure the Pioneer SX-950 rated at 85 wpc I picked up at a garage sale a couple of years ago for $10 would do an excellent job as would my JVC RX-500 B receiver rated at 100 wpc. OTOH, I have a Sony 5x 100 wpc GR3 AV receiver which would probably drop dead if I used it with AR3a. BTW, CDs can have far more powerful bass than vinyl recordings so be cautious. AR3 woofers were rated I think for 100 wpc continuous but tests showed they could handle over 1KW in a brief pulse. The tweeters and midrange drivers weren't nearly so robust. What do I use? My AR9s which have 2 AR 12" woofers each are connected to a 60 wpc Mosfet amplifier I built from a kit. They can play very loud without distortion in a 4000 cubic foot room on the live side. AR speakers were designed as very high accuracy high fidelity speakers for home use, not disco blasters or auditorium sound reinforcement units. While they can play very loud, if they are needed for these purposes, they can be used but multiple pairs would probably be advisable.

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Guest stankline

Thanks for all the helpful replies. I guess there is more to the problem than simple amp wattage. Can someone tell me what specifications I should look for in a receiver which will give me compatibility with my AR-3 speakers? I'd like to find something for under $200. Do I need to fix my original Electrovoice receiver? This output 25 wpc and gave adequate sound but I think I'd like a little more power.

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I seem to recall this receiver and its integrated amplifier only version. Strangely, if it's the one I'm thinking of, it might have been offered in both kit and factory wired versions. That particular unit only actually put out about 17 wpc RMS and was not a particularly fine performer. In those days, many manufacturers used the "IHF" (Institute of High Fidelity) method of testing which was much more lax and resulted in higher numbers by about 25% than the continuous or RMS method which was only used by a few exclusively (Marantz, McIntosh, Dynaco, Crown, AR.) In the mid 1970s, the FTC established rules making it easier to compare power ratings but amplifier performance is still much more complicated than a single number we'd like to reduce it to. The single largest, heaviest, and most expensive component of an amplifier is the power transformer. Its size gives a clue to its capacity, the conservativeness and capability of the power supply and hence overall quality. If I could only know one thing about an amplifier, I'd like to know how much it weighs (strange idea?) Other clues are quality of components and build quality, reputation of the manufacturer, openness of the layout. Many very high quality amplifiers and receivers which function perfectly are unwanted and unloved because they are not suitable for A/V systems or don't have the latest whizbang topologies or design catch phrases. As audio amplifiers are reaching the limit of what they can and cannot do, those older models become a great value, same as with AR speakers. Just avoid the ones which have become "collector" items. They command prices far out of proportion to their value as judged by comparable competitors.

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>I'd like to find something for under $200.<

That's a tall order, but it is doable if you'll settle for an integrated amplifier instead of a receiver.

http://www.pioneerelectronics.com/pna/prod...DetailComponent

That's not a bad choice that can be bought in your price range. Notice that Pioneer made a point of saying that this amplifier is stable into 4 ohms.

You can add a tuner to this at some other time from the used market for almost nothing if you need a tuner and probably stay in the $200 total price range.

If your heart is set on a receiver, something like this one might not be a bad choice and can probably be found for less than list price:

http://www.usa.denon.com/ProductDetails/587.asp

Notice, again, that this Denon specifically mentions both buzz-words you are looking for "high current" and "low impedance" capability (which may be considered the same thing).

Either of these would be a better choice than a "wimpy" 100w/channel A/V receiver.

There are probably other choices, but these are the two that I already knew existed.

Hope that's some help.

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Guest postjob62

Stan,

Take a look at this:

http://www.partsexpress.com/pe/showdetl.cf...tnumber=302-600

AudioSource Amp One/A

80 watts @ 8 ohms, 100 watts @ 4 ohms

Power is just about perfect.

It has adjustable level controls for each channel, so if you are just going to use a CDP for input, no preamp is needed.

Currently $196.00 at Parts Express with free shipping.

I have not tried this personally but it comes highly recommended to me by another member of the forum who is very knowledgeable and whose opinion I value very much. There are other good choices out there in this price range but many of them are oriented toward pro use and seem confusing at the consumer level.

Ed

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  • 1 month later...
Guest postjob62

Stan,

I don't know if you ever decided on an amp or not, but just wanted you to know that I in fact followed my own advice and purchased one of the AudioSource Amp One/A's from PE as I had mentioned in my earlier post.

I bought this amp based on the recommendation of this group's member Roy C., who I consider very knowledgeable and helpful. I can honestly report that used with my 3a's it has been one of the most satisfying purchases I have ever made. I would strongly recommend it to anyone looking for a power amp for classic AR's. It does not even blink at the 4 ohm load, and will push 3a's to a volume loud enough even for my taste with no sign of clipping. It also easily pushes a pair of TSW-610's. Price is still $199.00 at PE.

Best part about this amp for me is that it has built-in level controls which allow you to run your CDP directly into the amp without having to use a preamp. I actually find the sound better than using a preamp, even with the "loudness" button engaged. In fact, I cannot tell much if any difference between this setup and my Adcom GFA-5400 using a passive preamp.(More on this later).

Anyone looking for simplicity and quality at a reasonable price might give this a looksee.

Ed

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Guest postjob62

>

>This looks like an outstanding amplifier for the money - just

>the thing for an AR-3a!

AR-Pro:

It really is. I hate to sound like a commercial, but I keep thinking back to when I was pondering the "which amp to use with 3a's" question. Maybe this can help some others in the same situation.

I love my Adcom, and I know it is thought that one cannot have too much clean power. But if I had heard this first, I'm not sure I would have sprung for the Adcom or not. I'm using one of those skinny Toshiba DVD players as my CDP and I love the simplicity of not needing a preamp - plus, the sound is really amazing. With the Amp One/A putting out 100 watts at 4 ohms and the Adcom putting out 200, using the old axiom of a doubling in amp power producing a "just noticeable difference (3db) in volume, at any respectful volume I can't tell much if any difference. I'm sure that issues involving headroom come into play, but these are somewhat over my head and apparently over my abilty to hear as well.

Ed

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The American arm of Audiosource is also a well-known (in the industry)OEM supplier. I remember we used several Audiosource amplifiers for our powered subwoofers a few years back. Since powered subwoofer drivers are almost always 4-ohm units (in order to maximize the power available from the captive amplifier), we needed a solid, dependable, "tight" amp.

The Audiosource units we used (a 100-watter and a 300-watter) were superb: they sounded great, we never got them back for service, and they laughed at 4-ohm loads.

Steve F.

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I purchased an Audiosource Amp One about 10 years ago after reading a review in "Sensible Sound" magazine that compared it rather favorably with a $1600 amp. At that time it was equipped with power level meters and a button to engage a "soft clipping" circuit, and went for a discounted price of $250+/-. These features are no longer available, but it is a tough amp to beat for the current $200 price tag.

I've mostly used it without a preamp for testing speaker restorations as well as some serious listening (mostly AR-3a's) over the years. The amp and it's frequently used level controls have held up very well, showing no signs of wear.

Roy

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