Ken, is the NHT 1259 comparable to 12" AR woofers?

[soundminded]

Ken, is the Tonegen/NHT 1259 the driver comparable to AR 12" woofers? I've noticed it is 6 ohms. It appears to be a superb unit and I'm sure all DIYers will be most appreciative of the extensive information you've supplied for it. Here's the web page for anyone who is interested in it.

http://www.arsenal.net/speakers/ar/documen...20Questions.htm

[soundminded]

If you download the NHT 1259 data sheet from Madisound's catalog page, you will find some differences between their data and the data on the page I referenced. I'm not quite sure of its significance. You'll also see that it is now available in an 8 ohm version. However, there are some tradoffs for the 8 ohm speaker. It has a higher Fs, lower mass, and is 3 db less sensitive. I'm assuming that the 4 ohm version is not a drop in equivalent of the AR 12 inch woofer even given the lack of the truncated geometry notwithstanding. But it still looks to be an outstanding driver.

Any idea what became of A & S Speakers? They no longer have the phone number on the FAQ page.

[dynaco_dan]

>Ken, is the Tonegen/NHT 1259 the driver comparable to AR 12"

>woofers? I've noticed it is 6 ohms. It appears to be a

>superb unit and I'm sure all DIYers will be most appreciative

>of the extensive information you've supplied for it. Here's

>the web page for anyone who is interested in it.

>

>http://www.arsenal.net/speakers/ar/documen...20Questions.htm

Just a quicky comment that I read somewhere else recently. The required enclosure is much greater than the AR cabinets for the 1259 speaker. I hope I'm wrong but this is recent news from somewhere I was reading this year. I remember when someone wrote into the Audio Amatuer and apparently was organizing a group purchase at $150.00 each I think. I was slightly interested when the AR3a foam surrounds first went south as the 1259 has a rubber surround. But it would have cost me about $250 - 300.00 cdn landed so I opted to re-foam. Yuch. I am going to try a rubber surround on the AR3a woofers as an experiment otherwise every 10 years or so a re-foam job. Built in obsolesents. Have a great one. Vern

[soundminded]

I had a chat with someone from Madisound today. The NHT 1259 is a superb acoustic suspension subwoofer which they claim will outperform the AR 12" woofer. However, it's optimal enclosure size is 3.5 cubic feet, twice the volume of an AR3/AR3a type enclosure. It may also not be suitable for use as a woofer, I really don't know at this point. Madisound's rep said that a common crossover frequency for it is 100 hz even though the claimed response is 1Khz. The example given in the Tempest DIY design crosses it over at 300 hz. The man I spoke with also recommends 0.5 lbs of insulation per cubic foot compared to 1.0 for the AR woofer. I don't know if this is right. It doesn't seem right especially after reading the design for the Tempest. It seems to me that the only way to know for sure is trial and error just the way AR must have done it originally. How this compares with the Peerless driver PeteB referenced or the Dayton Titanic Mk III is impossible to say without buying them and putting them through their paces. On paper the Titanic Mk III 12 " and even more the 15" look very impressive. I am sure any of these will perform beautifully if the enclosure and crossover are well matched to the driver. However, without a real shootout by an impartial critic, it's impossible to say at this point. To those who dismiss all of this as superfluous because we are discussing Acoustic Research here, all I can say is that something would be very wrong if 50 years could not advance the state of the art of hardware for this type of driver beyond Ed Vilcher's original driver design. Theil Small notwithstanding, IMO, this is still the ultimate technology for low frequency high fidelity sound reproduction and the one to beat. It's too bad that the industry has degenerated to a state where performance from even the most expensive products is so poor that people selling $10,000 speaker systems recommend you buy a subwoofer if you want deep bass performance from your sound system. How lucky we are here to have an embarrassment of riches debating which of the top performers is the champ for the moment.

I am now convinced that the Teledyne AR9 speakers I bought in 1984 have original AR 12" drivers and not Tonegen even though they have truncated edges unless Ken tells me otherwise. Madisound's sales tech said that the 3.5 to 4.0 cu feet of the AR9 enclosure would not be suitable for a pair of 1259s and I believe him.

[Guest Bret]

>How lucky we are here to have an embarrassment of riches debating which of the top performers is the champ for the moment.<

I've been looking-around, reading, etc. I have a need for four, small, speakers. I've pretty-much decided that I'm going to have to have a subwoofer. You just can't cut your teeth on an AR-1w then believe anything with 6" driver and a hole in the cabinet can produce bass.

Anyway, your comment about the top-performers brought something to mind.

Look at the link. I love it. Why couldn't I have been just a few years older? These guys are having way too much fun.

http://www.passdiy.com/projects/el-pipe-o-1.htm

Bret

[Pete B]

I hesitate to jump in here because I've been through this before.

That FAQ has many errors, it is and never was a 6 ohm (Rvc is 3.5 ohms) driver, there is no 8 ohm version unless they have one hiding somewhere, the moving mass is wrong, the vented numbers are absurd. Why are the vented numbers absurd, because I dared to suggest that the driver would work well in a vented alignment on the old bass list many years ago. They used an absurd alignment not one that I suggested and I believe they chose a defective simulator. I didn't just say this off the cuff, I actually took the time to simulate it before I suggested a vented alignment and it works just fine. I have now built it, those woofers in the big monitors at my page are 1259s vented at a very low frequency. The system is amazing, the few people who've heard it are amazed, it doesn't sound vented. The comments are not just about the deep extension but also about how amazingly tight the system is. It is easy to plug the ports to compare the performance to sealed and then there is a significant reduction in 20 Hz output, both from a frequency response standpoint and a maxspl standpoint. But I'm sure people who want to believe that it's not possible will continue to do so.

As far as the 1259 goes, as I remember, it was the first of the extra long throw woofers, most at that time were 3 to 8 mm Xmax, the 1259 was 13mm (one way) or just over an inch peak to peak. Since then there are many more drivers that are very similar, the key features are a cone mass of 100 to 120 grams, high Vas, and Xmax around 12 to 16mm. Another thing to worry about is the real world linearity of the motor (Xmax is theoretical) which can be determined through DUMAX or some of the newer test methods. The large signal bargain performance king is Shiva and you can see performance comparisons at their web site. I'm not endorsing it, I'd probably choose another driver for subtle reasons, but the raw performance numbers are probably accurate.

There is even a newer breed of super subwoofers which take Xmax to over 25mm, some are doing 3 inches peak to peak, now that's a subwoofer. http://www.adireaudio.com/images/tumult_back_small.jpg

Anyway, in addition to my vented simulatins for the 1259 I've simulated it in 1.5 to 1.7 cu ft enclosures and yes Fc and Qtc are higher than a true sub, but it is workable by using an inductor with very low DC resistance and extra damping behind the driver. Don't bother to tell me how it won't work based on common knowledge and because expert XYZ says so, because then I will go build it and prove you wrong. Will it replace an AR3 woofer and sound exactly the same, no it will certainly sound better if I do it. Obviously, it has to physically fit the cutout and I don't think it does in an AR3 type box.

There is no exact optimal enclosure size it's even possible to use a Linkwitz transform to make an almost arbitrary enclosure sound like another: http://www.linkwitzlab.com/filters.htm#9

There are many good simulators for sealed box design and very little trial and error is required to get in the ballpark or to compare different alignments. I said I'd want to hear the Peerless because perhaps it might have particularly good large signal performance, even with a less than optimal alignment. Final listening is always important to hear the large signal performance, fine tune, etc.

By the way if you believe the statements about the optimal enclosure size, then the 1259 in the NHT 3.3 is in a less than optimal enclosure, go look up the volume. I've already simulated the entire system.

I'm not suggesting the 1259 is, or is not a drop in replacement for anything however, as I said originally, it would be interesting to design a AR3a sized system with a 1259 or another of the newer and better drivers, that far outperforms it.

Peace and enjoy the music!

>I had a chat with someone from Madisound today. The NHT 1259

>is a superb acoustic suspension subwoofer which they claim

>will outperform the AR 12" woofer. However, it's optimal

>enclosure size is 3.5 cubic feet, twice the volume of an

>AR3/AR3a type enclosure. It may also not be suitable for use

>as a woofer, I really don't know at this point. Madisound's

>rep said that a common crossover frequency for it is 100 hz

>even though the claimed response is 1Khz. The example given

>in the Tempest DIY design crosses it over at 300 hz. The man

>I spoke with also recommends 0.5 lbs of insulation per cubic

>foot compared to 1.0 for the AR woofer. I don't know if this

>is right. It doesn't seem right especially after reading the

>design for the Tempest. It seems to me that the only way to

>know for sure is trial and error just the way AR must have

>done it originally. How this compares with the Peerless

>driver PeteB referenced or the Dayton Titanic Mk III is

>impossible to say without buying them and putting them through

>their paces. On paper the Titanic Mk III 12 " and even more

>the 15" look very impressive. I am sure any of these will

>perform beautifully if the enclosure and crossover are well

>matched to the driver. However, without a real shootout by an

>impartial critic, it's impossible to say at this point. To

>those who dismiss all of this as superfluous because we are

>discussing Acoustic Research here, all I can say is that

>something would be very wrong if 50 years could not advance

>the state of the art of hardware for this type of driver

>beyond Ed Vilcher's original driver design. Theil Small

>notwithstanding, IMO, this is still the ultimate technology

>for low frequency high fidelity sound reproduction and the one

>to beat. It's too bad that the industry has degenerated to a

>state where performance from even the most expensive products

>is so poor that people selling $10,000 speaker systems

>recommend you buy a subwoofer if you want deep bass

>performance from your sound system. How lucky we are here to

>have an embarrassment of riches debating which of the top

>performers is the champ for the moment.

>

>I am now convinced that the Teledyne AR9 speakers I bought in

>1984 have original AR 12" drivers and not Tonegen even though

>they have truncated edges unless Ken tells me otherwise.

>Madisound's sales tech said that the 3.5 to 4.0 cu feet of the

>AR9 enclosure would not be suitable for a pair of 1259s and I

>believe him.

[Pete B]

That must have been some party where they blew the the drivers.

I don't believe that a pair of AR1/3 type woofer boxes comes even close to any sort of ultimate system, eight would be more like it. I wouldn't even call them sub woofers by today's standards.

[Guest rickcee]

I'm gonna throw this out as a curiosity, sugestion, or whatever.

The late '90's AR 303 ( and 10 " AR 302) have rubber surround .Designed by 'our' K.Kantor ?)( I believe) and the boxes are close to original AR 3 and AR 5.

perhaps the woofers from these are avail, I forget the name of the semi official AR / Advent replacement parts company.

enjoy Rick

(AR 302 ,Dyna 25, KLH 17 late '70's Koss 1020, , see other post on thiel computer design, from stereo review test " plus minus 2 db from 20 - 5,000 hz." Sept '79 ?)

[soundminded]

From what I can tell, the drivers were not a good choice. They are no longer on the referenced website so I could not get any data. Often professional drivers have a resonant frequency that is rather high for their size and are much better suited to auditorium sound reinforcement systems than home high fidelity sound use. The unequalized falloff in fig 13 at the low end starting at about 80 to 90 hz is particularly disappointing. When it gets down to the very low frequencies it falls off at about 10 db per octave. At least the choice of a second order filter made a lot of sense. I don't think that this speaker performs better than AR9 if that well. One thing living with AR9 has taught me is that what they say about tieing every loose item in the room down is important. It's also interesting that you can hear differences in the level of bass not only according to where you place the speakers but where you sit. Not only is acoustic feedback a problem for just about any turntable, but it made my old cd player jump off track. You can also hear a lot of recorded rumble and other low frequency disturbances on many cds you won't hear from practically any other speaker.

The fact that AR was able to successfully perform live versus recorded demonstrations with the Aolean Skinner pipe ogan 40 years ago using AR3s is testamony to their low end capability. The only real objection to those speakers low end performance limitations in those days was that adequate amplifier power and equalizers were very expensive. That's not an objection any longer. IMO, the Acoustic suspension principle still remains the best and most practical method for low frequency sound reproducton in the home. The ingenuity of integrating the AR9 subwoofers into both the room acoustics and with the remainder of the system proves just how much real thought went into this problem at AR. Most subwoofers are haphazardly added and IMO have real problems integrating into the rest of the system without major frequency response irregularities. I'm sorry to say that other loudspeaker designs even running into the tens of thousands of dollars recommend the addition of a subwoofer to reproduce the lowest audible octave and more. That is not high fidelity IMO. It's also not acceptable value for money.

[Guest Bret]

>Often professional drivers have a resonant frequency that is rather high for their size<

Somewhere in that article is the resonance for those drivers. I remember thinking it was, exactly as you say, awfully high.

But driver choice aside, that was just the kind of fun that I haven't had since I turned 22.

Bret

[soundminded]

What was disappointing about it was that the whole goal was to create a subwoofer which would have an in box resonance frequency which would put the whole lowest octave and maybe the first subsonic octave in the forefront instead of where it is usually found which is where the system is petering out or just plain gone. I'm sure that these drivers were very expensive. I just think they were the wrong choice. The unequalized result didn't look any better to me than many other speaker systems. BTW, this doesn't seem particularly novel. Even the Bose wave radio uses a transmission line to extend bass. Doesn't it?

[tysontom]

>That must have been some party where they blew the the

>drivers.

>

>I don't believe that a pair of AR1/3 type woofer boxes comes

>even close to any sort of ultimate system, eight would be more

>like it. I wouldn't even call them sub woofers by today's

>standards.

That is a preposterous statement! No one would sensibly suggest anything like that for any type of ultimate system for use in the home. What is the purpose of a sound reproducing system? Do you want to recreate the actual sound-pressure levels in the home that are required for an auditorium or huge sound-reinforcement system or something of that nature? The idea is to be taken to the concert hall, not bring the concert hall into your house.

I think that what Soundminded was saying in another post was that The New York Audio League many years ago used four AR-1s in a live-vs.-recorded session comparing a large Aeolian-Skinner pipe organ to these AR speakers. This was done before an audience of over 600 people, including music critics and reviewers, etc., and the overall consensus was that four AR-1s -- driven by four Fairchild mono amplifiers -- reproduced the deepest pedal tones of that pipe organ at full power in a way that no one in the audience could tell the difference. Can you imagine the SPL in your living room if you had a huge Aeolian-Skinner pipe organ in there? But four AR-1s were able to reproduce the *full* power of that organ. That first live-vs.-recorded demonstration was not done by AR; it was conducted by an independent organization without the help of AR. This was also an early demonstration of the potency of the AR woofer, and this session has always been considered a watershed in sound-reproduction even to this day.

The hallmark of AR woofers is their very low harmonic distortion -- typically lower than most other woofers of comparable performance. Because of this low distortion, the woofers can be equalized down to 20 Hz without problems. For example, a pair of AR-3s or AR-3as with proper equalization such as the Allison ESW, for example, can produce clean bass down to 20 Hz with very low distortion. There are any number of ported systems today, with proper alignment, that can reach down low, but typically problems can arise with regard to distortion, damping and power-handling capability at subsonic frequencies. Many a ported speaker (except for the most robust new drivers), tuned to very low frequencies, is susceptible to severe distortion or damage at subsonic frequencies.

Here is another example: I have a pair of AR-303a speakers that are equalized flat to 20 Hz, driven by a very hefty Crown pro amplifier. I also have a Velodyne ULD-18 subwoofer, considered by many to be among the more potent subwoofers available for home use. It’s 18-inch woofer can pump back and forth about 1-1/2 inches before limiting comes into play. I can switch the Velodyne in and out in my system, and to be perfectly honest with you, the AR-303as are a reasonable match for the Velodyne until you get to uncomfortably loud, scary levels. I also put a pair of excellent NHT1259 woofers in this same pair of AR-303as, and the low frequency performance was marginally improved -- not as much as you would think, but the rest of the mid-bass spectrum balance was badly upset. I removed these woofers and put the stock units back in place. The point is, however, that the equalized 12-inch AR woofer (in this case the AR-303 woofer) was almost as good as the Velodyne up to a point where the sound level became uncomfortable. You don’t need eight AR woofers to reproduce bass in the home.

--Tom Tyson

[Guest Bret]

> BTW, this doesn't seem particularly novel. Even the Bose wave radio uses a transmission line to extend bass. Doesn't it?<

Oh yeah. I didn't mean to imply that a transmission line was novel, I just thought putting a kw amplifier on some speakers sitting beneath a 12' Sonotube was novel. The more I think about this, the more I'm unsure that the space between the ceiling and the end of the tube wasn't acting as a tuned vent of sorts and goofing-up the entire experiment. It wasn't the result I found impressive. If I want an impressive end result I don't have to look any further than Carver's little subwoofers (not to be confused with Carter's little pills) and then I can go "Golly."

I dunno. . . maybe I should get out more, but it still seems like an interesting way to kill a weekend. I think I could like these guys. You can't take yourself too seriously and still do something like this.

Bret

[soundminded]

As I recall, tests on AR 12 inch woofers performed many years ago, probably at CBS or Hirsch Houck laboratories showed that they could produce 30 hz tones with 5% harmonic distortion which was about half of the best competing woofers of the time (and a small fraction of most of what was on the market) and could also handle over one kilowatt of impulse power. This is sure testimony to their robustness and accuracy. The original Velodyne design relied on servo feedback using an accelerometer to correct for cone motion errors. This idea when properly executed is an excellent design concept but it's very expensive. Failure of the servo circuit of course could spell disaster without some sort of protection to the woofer. The infinity Servo Static I and Ia of the early 1970s, Infinity's first products also used a servo system woofer and may have been the first subwoofer/satellite system on the market. (The rest of the audio spectrum was handled by large electrostatic panels.)

While vented systems can be tuned to very low frequencies, it is difficult to see how you can get around their highly resonant nature. The very act of tuning a vent to one frequency no matter how low suggests that as you move away from that frequency, there will be a radical change in output due to the mechanical impedence of the air column in the vent. A sharp cutoff electrical filter to prevent undamped oscillation at one half the tuned frequency only makes the overall resonant nature of the system worse. Therefore, the resonant frequency is effectively the low end limit of the system. Falloff below resonance is usually very steep and unlike acoustic suspension systems cannot be compensated for with electrical equalization. I suspect that PeteB would disagree with this view strongly so I'm interested to hear why he thinks it isn't true. His extensive mathematical modeling of these systems should give some insight as to what the state of the art of vented systems is and what the current thinking is today.

[tysontom]

The AR 12-inch woofer is a known quantity, and no excuses need be made for its bass performance.

My argument was over this statement: “…I don't believe that a pair of AR1/3 type woofer boxes comes even close to any sort of ultimate system, eight would be more like it. I wouldn't even call them sub woofers by today's standards….” If four AR-1s could reproduce a huge pipe organ in a church, doesn’t it follow that two AR speakers could handle the load in an average home listening room?

As for the “subwoofer” comment, I don't think there is a *precise* definition as to what constitutes subwoofer performance. There are any number of speakers claiming to be “subwoofers” that do not even approach the performance of an AR 12-inch woofer. On the other hand, most true subwoofers should be capable of reproducing low bass down into the subsonic region of 20-40 Hz; and although the AR woofer will reproduce bass down to 20 Hz, it needs some equalization to get down flat to 20 Hz to compensate for the normal rolloff below resonance when mounted in the normal 2 Pi fashion.

--Tom Tyson

[ToastedAlmond]

Wasn't it Ken Kantor who not so long ago said, "The AR-9 loudspeaker set the standard for deep bass performance in its day, and to this day."

George

[soundminded]

Results of my 20 years of experience with AR9 verifies this statement. It is hard to imagine why anyone would need to be able to outdo AR9. Equalization compensating for the natural driver rolloff in the enclosure and for the room low frequency cutoff has conviced me that this loudspeaker can easily reproduce any low frequency of interest in music to below audibility. This is demonstrated by the speaker's ability to jar some compact disc players into losing tracking lock with some recordings unless unusual precautions are taken. (For turntables, limiting low frequency output is a must if acoustic feedback is to be avoided.) It can also reproduce cannon shots and thunder quite well. About the only problem with AR9 is that you can't get it anymore except used. 60 wpc will drive a pair to deafening levels in a 4000 cubic foot room of slightly brighter than average acoustics. IMO, the 200 hz cutoff of the 12" drivers was a wonderful idea limiting their response to what they do best and employing an 8" driver for the upper bass/lower midrange. I think this solved several problems including matching the upper range of the woofer to a dome midrange and neatly reducing or eliminating the phase cancellation problem of the room acoustics. Tim Holl's explanation makes a lot of sense to me and the speaker seems to work exactly as he says it does.

[tysontom]

As said before, the AR-9 set the standard for deep-bass reproduction when it was introduced in 1978, and it remains a standard to this day. There are some very heavy-duty subwoofers that can produce more bass output in the subsonic frequencies, but there are probably few standard loudspeakers that can equal the AR-9. Once again, the hallmark for this clean-bass reproduction was low distortion. The AR-9 had very low harmonic distortion as shown in the many tests and reviews done by *Stereo Review,* *High Fidelity* and *Audio* magazines in the late 1970s.

The AR-9 was also very flat down to 28 Hz; and because the woofers were mounted close to the floor-wall intersection, there was the near-elimination of the destructive boundary-interference effects. The low crossover of 200 Hz, and the distance from the midrange drivers also helped. In mounting the woofers the way they did, AR put some of Roy Allison’s design work to good use in the AR-9.

--Tom Tyson

[Pete B]

You look at graphs and think that the system was disappointing, what about maxspl which is not shown. What about actually hearing the system I'll bet that the people who heard it were not disappointed. You really ought to do some research before throwing out the worn out AR is best no one will ever outdo an AR9, absurd belief in marketing literature, and contrived marketing live vs. speaker demonstrations. I'm sure they very carefully chose the type of music, environment, and speaker to listener distance. Different from the home environment and does not cover all types of music.

The system was EQed to 13 Hz and then was driven with 4 KW peaks, try that with your AR9, I guarantee you that it will mostly produce distortion at 13 Hz. Even the 1259 has very high distortion at 20 Hz and moderate drive levels. Vented and/or TLs lower distortion that is a fact.

Just offering my opinion take it for what it's worth.

>What was disappointing about it was that the whole goal was

>to create a subwoofer which would have an in box resonance

>frequency which would put the whole lowest octave and maybe

>the first subsonic octave in the forefront instead of where it

>is usually found which is where the system is petering out or

>just plain gone. I'm sure that these drivers were very

>expensive. I just think they were the wrong choice. The

>unequalized result didn't look any better to me than many

>other speaker systems. BTW, this doesn't seem particularly

>novel. Even the Bose wave radio uses a transmission line to

>extend bass. Doesn't it?

[tysontom]

>You look at graphs and think that the system was

>disappointing, what about maxspl which is not shown. What

>about actually hearing the system I'll bet that the people who

>heard it were not disappointed. You really ought to do some

>research before throwing out the worn out AR is best no one

>will ever outdo an AR9, absurd belief in marketing literature,

>and contrived marketing live vs. speaker demonstrations. I'm

>sure they very carefully chose the type of music, environment,

>and speaker to listener distance. Different from the home

>environment and does not cover all types of music.

>The system was EQed to 13 Hz and then was driven with 4 KW

>peaks, try that with your AR9, I guarantee you that it will

>mostly produce distortion at 13 Hz. Even the 1259 has very

>high distortion at 20 Hz and moderate drive levels. Vented

>and/or TLs lower distortion that is a fact.

>

>Just offering my opinion take it for what it's worth.

>

I'm just curious, PeteB, what is the purpose of 13 Hz, driven with 4 KW peaks? I really feel that I am missing something important here.

--Tom Tyson

[Pete B]

Preposterous no, not if you prefer low distortion bass with all source material. I suggest you watch what you post toward me I find that offensive.

Have you studied the power spectral balance of source material? There is some material, movie sound effects and cannons such as on the Telarc recordings and very common movies with high level content down to 10 to 12 Hz, few systems can reproduce the fundamental with any sort of reasonable distortion even get above the threshold of hearing, for the fundamental.

The NHT Tenth Anniversary sales literature shows a harmonic distortion plot for the NHT 3.3 which I'm sure you know uses a 1259 woofer. Distortion is 2.5% at 2.83V input at 20 Hz, that's approximately two watts into the system, I run more than 300/ch and hit the clip lights on heavy bass passages.

As I said I prefer low distortion bass - don't know exactly what your looking for. Don't impose your standard for ultimate on me, it appears that my standard is higher. Many mastering engineers run kilowatt amplifiers and high end speakers way beyond AR3a's or AR9s in a home type of environment - are you going to tell me they're all wrong and you and the AR gang in here are right? Your positions and claims are almost laughable by today's standards.

I'm outta here this is obviously an AR can do no wrong site.

>>That must have been some party where they blew the the

>>drivers.

>>

>>I don't believe that a pair of AR1/3 type woofer boxes comes

>>even close to any sort of ultimate system, eight would be

>more

>>like it. I wouldn't even call them sub woofers by today's

>>standards.

>

>That is a preposterous statement! No one would sensibly

>suggest anything like that for any type of ultimate system for

>use in the home. What is the purpose of a sound reproducing

>system? Do you want to recreate the actual sound-pressure

>levels in the home that are required for an auditorium or huge

>sound-reinforcement system or something of that nature? The

>idea is to be taken to the concert hall, not bring the concert

>hall into your house.

>

>I think that what Soundminded was saying in another post was

>that The New York Audio League many years ago used four AR-1s

>in a live-vs.-recorded session comparing a large

>Aeolian-Skinner pipe organ to these AR speakers. This was

>done before an audience of over 600 people, including music

>critics and reviewers, etc., and the overall consensus was

>that four AR-1s -- driven by four Fairchild mono amplifiers --

>reproduced the deepest pedal tones of that pipe organ at full

>power in a way that no one in the audience could tell the

>difference. Can you imagine the SPL in your living room if

>you had a huge Aeolian-Skinner pipe organ in there? But four

>AR-1s were able to reproduce the *full* power of that organ.

>That first live-vs.-recorded demonstration was not done by AR;

>it was conducted by an independent organization without the

>help of AR. This was also an early demonstration of the

>potency of the AR woofer, and this session has always been

>considered a watershed in sound-reproduction even to this

>day.

>

>The hallmark of AR woofers is their very low harmonic

>distortion -- typically lower than most other woofers of

>comparable performance. Because of this low distortion, the

>woofers can be equalized down to 20 Hz without problems. For

>example, a pair of AR-3s or AR-3as with proper equalization

>such as the Allison ESW, for example, can produce clean bass

>down to 20 Hz with very low distortion. There are any number

>of ported systems today, with proper alignment, that can reach

>down low, but typically problems can arise with regard to

>distortion, damping and power-handling capability at subsonic

>frequencies. Many a ported speaker (except for the most

>robust new drivers), tuned to very low frequencies, is

>susceptible to severe distortion or damage at subsonic

>frequencies.

>

>Here is another example: I have a pair of AR-303a speakers

>that are equalized flat to 20 Hz, driven by a very hefty Crown

>pro amplifier. I also have a Velodyne ULD-18 subwoofer,

>considered by many to be among the more potent subwoofers

>available for home use. It’s 18-inch woofer can pump back and

>forth about 1-1/2 inches before limiting comes into play. I

>can switch the Velodyne in and out in my system, and to be

>perfectly honest with you, the AR-303as are a reasonable match

>for the Velodyne until you get to uncomfortably loud, scary

>levels. I also put a pair of excellent NHT1259 woofers in

>this same pair of AR-303as, and the low frequency performance

>was marginally improved -- not as much as you would think, but

>the rest of the mid-bass spectrum balance was badly upset. I

>removed these woofers and put the stock units back in place.

>The point is, however, that the equalized 12-inch AR woofer

>(in this case the AR-303 woofer) was almost as good as the

>Velodyne up to a point where the sound level became

>uncomfortable. You don’t need eight AR woofers to reproduce

>bass in the home.

>

>--Tom Tyson

>

[Pete B]

I'm not suggesting that I need 13 Hz and 4 KW, actually I'd probably go for 10 Hz, and 1 KW but it would depend on how efficient the system was. Look up a few papers on the power spectrum of available source material. My point is that Soundmind looks at frequency response curves and thinks he knows better than people who actually heard the system. MaxSPL curves would have told a lot more.

>

>I'm just curious, PeteB, what is the purpose of 13 Hz, driven

>with 4 KW peaks? I really feel that I am missing something

>important here.

>

>--Tom Tyson

>

[soundminded]

PeteB, rather than get into a childish arguement of is not/are too, I'd like your opinion about one aspect of El Pipe-O which puzzles me. The woofers have an advertised free air resonance of 25hz. The Pipe is specifically tuned to around 20 hz. How do you account for the graph of the near field frequency response in figure 13 which suggests that the system resonance point is 90hz, that response falles off 5 db at 35 hz, and then continues to fall at about 10 to 12 db per octave? Do you think the 20 pounds of dacron overdamped the system and pushed the resonant frequency up that far?

As for acoustic suspension systems, the falloff is about half ported systems. Bose 901 series I and II which was an acoustic suspension design had its system resonance deliberately pushed up to 180 hz where Dr. Bose claimed the phase shift associated with resonance is no longer audible. He paid a heavy price for this probably dooming the design because the power requirements to reproduce very low bass meant too high a cost for most audiophiles at the time. A lower resonance frequency using a larger enclosure would have lessened this demand considerably. Never-the-less, his system was successfully equalized extending its response 3 octaves down to 23 to 26 hz. Extrapolating this for If AR9 with its system resonance of 28 hz, if it could be similarly extended (too great an assumption?) its response could be extended to around 4 hz. Of course the power requirements at that frequency would be enormous and it may not be able to produce very loud spl within the maximum electrical capacity of the drivers. Do you think this is possible?

[ar_pro]

One of my earlier pairs of rebuilt 9s successfully reproduced a 16 Hz sinewave using independent active equalization on the LF half of the 9's crossover. An Audio Control *Richter Scale* EQ was matched with a passive preamp and Crown Macrotech power amp.

[tysontom]

Extrapolating this for If AR9 with its system resonance of 28 hz, if it could be similarly extended (too great an assumption?) its response could be extended to around 4 hz. Of course the power requirements at that frequency would be enormous and it may not be able to produce very loud spl within the maximum electrical capacity of the drivers. Do you think this is possible?

Soundminded

One important thing to remember about a direct-radiator system is that for a given acoustic-power output, the cone velocity doubles and cone excursion *quadruples* for each lower octave down to resonance. For this reason the resonance of a properly designed speaker usually is not set any lower than the excursion capability of that woofer for a given power rating of that speaker.

Below the 28 Hz resonance in the AR-9, for example, excursion remains constant but the output drops at the predictable rate of 12 dB/octave -- for a given input power. Since the AR-9 can produce low-distortion, high SPL levels down to its resonance, it is therefore capable of relatively high, if reduced, SPL levels down to below 20 Hz. Reproducing 4 Hz would be a stretch for any loudspeaker ever made! Speakers might respond to it, but no signicant fundamental energy would be reproduced.

The only musical sound below 16 Hz is the 8 Hz 64' organ pipe, and I believe that there are only two or three organs in the world that have it. I don't think any music has ever been written using those pipes, although quite a bit of music has 16 Hz 32' organ notes.

--Tom Tyson