Jump to content

ForA-9 Speaker Concept Based on the AR-9, by Pete B.


Pete B

Recommended Posts

The ForA-9 Speaker System Concept, by Pete B.

Here are some thoughts on a modernized design following the AR-9 concept. I'm going to call it the ForA-9.

I might offer several suggestions for different component cost targets. I usually find designing to cost to be the most challenging, however the following uses mostly premium drivers still in a sensible way. The woofer section will be close to or below 4 ohms whereas the midranges are around 6 ohms and would have to be checked for voltage sensitivity to determine if they're suitable. Smaller versions of these drivers could be paired up in parallel if higher sensitivity is required.

TWEETER:

I suggested the Vifa 3/4" tweeter as an AR3a/LST replacement in response to those looking for a 2.75 ohm RDC tweeter. It seems to fit the AR-9 better from a look an feel point of view since the AR-9 is a newer and more modern design. The word out is that this .75" driver has excellent characteristics almost keeping up with many 1" domes. This .75" is chosen just to stay with what was used in the original otherwise I'd go with a 1" or perhaps a ribbon. These Vifas, really all drivers, should be inspected and tested at least for basic parameters because they are mass-produced parts with average consistency. The similar Scan ring radiator is another much more expensive alternative if one really wants to spend more:

Vifa XT19TD00:

http://www.partsexpress.com/pe/pshowdetl.c...r=264-580&DID=7

http://www.partsexpress.com/images/264-580m.jpg

Scan 1" ring radiator (about $450):

http://www.d-s-t.com/scs/data/foto_r2904_700000.jpg

UPPER MID:

The upper midrange would be the premium SEAS M15CH001 midrange from their Excel Line:

PDF: http://madisound.com/E0016.pdf

http://ldsg.snippets.org/graphics/seas/e0016.jpg

LOWER MID:

The lower 8" midrange would also be a premium SEAS W22EX001 Excel woofer which has been tested by many and has excellent distortion characteristics:

PDF: http://madisound.com/seas/e022.pdf

Picture is a similar 8" Excel SEAS:

http://ldsg.snippets.org/graphics/seas/e004.jpg

WOOFERS:

Would want to evaluate several 12 inch woofers, here are a few:

SAE-1204:

http://www.apexjr.com/images/SAE1204-front.jpg

http://www.apexjr.com/images/SAE1204-side.jpg

Fs =21 but the cone mass is 177 grams providing a low Fc in a

fairly small box.

Cast aluminum frame

Double stacked 120 oz magnet to avoid bottoming.

2.5" voice coil

14.3 mm Xmax, that's one way, more than twice the AR-9 woofer.

Approximate AR-9 Unibox simulation shows Fb = 33.03 Hz and F3 = 28.31

Eminence LAB-12:

http://www.partsexpress.com/pe/pshowdetl.c...r=290-570&DID=7

http://www.partsexpress.com/images/290-570m.jpg

Adire Audio DPL-12:

http://www.adireaudio.com/TextPages/DPL12PageFrameText.htm

http://www.adireaudio.com/images/DPL12.jpg

This speaker concept has been on my mind, just wanted to get it down on paper.

Thoughts?

Link to comment
Share on other sites

  • Replies 55
  • Created
  • Last Reply

Designing a new speaker "on paper," using various readily-available drivers, is certainly one of the more entertaining mental exercises an audio enthusiast can undertake. However, it’s rarely as clean and easy in actuality as it seems in theory. If it were that easy, there would a lot more great speakers out there, and products as innovative and long-lasting as the AR-3, 3a, LST, 10 Pi, and 9 would come along every day, instead of once or twice a decade.

What all these great AR speakers had in common was this: There was a readily-identifiable problem at hand, and the designers set out to solve it. The solution often required them to invent brand-new technology, or to utilize existing technology is a completely new way.

The issue with trying to update an existing design is that one is, essentially, putting the cart before the horse, as it were. "Parts bin-engineered" products are never as successful as their more original problem-inspired brethren. The TSW-910 is the classic example of this. AR essentially said, "Well, we need an AR-9ish kind of product to fill out the line. A big floorstander that does that dual-woofer thing. Lots of mids and tweets. Sells for about $xx.xx." So they came out with the 910,and it was not anywhere near as successful or memorable as the 9 or 9LS, both of which solved real, tangible, identifiable problems. The 910 just filled a marketing void.

From a pure engineering standpoint, what exactly is the problem that is being addressed by the ForA-9 speaker that the 9 didn’t accomplish? Is ultimate SPL the issue? Smoothness of response? Lower THD? Better room-matching? Wider dispersion? What are the engineering goals? As Yogi Berra once said, "If you don’t know where you’re going, you’ll probably wind up someplace else."

Some of the driver suggestions here reflect the arbitrary nature of this kind of endeavor. "Well, it has to be a 4-way if we’re going to duplicate the 9, so how about THIS as an upper mid?" The 9 wasn’t designed to be an "x"-way from the start. It was designed to solve the problems of room-matching, deeper bass extension than the 3a/LST, and more uniform horizontal dispersion. The engineering objectives dictated how many "ways" it was, what the drivers’ capabilities were, etc. It came out as a "4-way" because that’s what was needed to meet the design objectives. AR did NOT say to themselves, "Let’s do a 4-way; now what drivers can we throw together?" See the difference?

BTW, that SEAS M15CH001 midrange has a free-air resonance of 54Hz, and looking at the supplied curve, it appears to respond cleanly down below 100Hz. This is clearly not an "upper-midrange"-only driver and it illustrates the difficulty of preconceiving a particular complex design and then searching around for the bits and pieces to fit the puzzle. The AR-9 used a 1 1/2" dome upper mid for reasons of wide dispersion. That was an engineering objective. The AR upper-mid dome will have far better dispersion in the range from around 3000-7000Hz than this SEAS will, which is why AR used that driver. It met their objective. The 8" lower mid was then the perfect solution to having a driver that was robust enough to take over from the woofs at a low-ish 200Hz and respond smoothly up the 1200Hz x-o point to the upper mid. Each driver was designed and utilized for a specific reason, to accomplish a specific task within the system.

As presented, it seems as if we’re being asked to ponder in the abstract whether this arbitrary assemblage of commercially-available drivers from various sources would duplicate the performance of an AR-9, with the added—although unstated—implication that the sheer "quality" of these drivers might somehow result in a "better" speaker than the original. This is fun, but it’s not the way real speaker engineers go about their jobs. (At least, it’s not the way they go about their jobs before the scabs from Marketing get involved. Then it’s EXACTLY how they go about their jobs. I know, all too well, having spent many years on both sides of the fence.)

Steve F.

Link to comment
Share on other sites

As an AR 9 owner for 21 years, I have several criticisms of this speaker system some of which can be addressed by enhancements and others which would require redesign.

Specifically, the voicing does not sound flat to me on commercial recordings using the program controls in any combination of settings. Furthermore, the high frequency dispersion excellent as it is is not nearly adequate. (This is not a criticism of just this speaker but all single tweeter direct firing systems.) This in part IMO explains inability of the speaker to sound flat. The fix which I used was to add more tweeters and use an equalizer.

In comparing the sound of direct firing loudspeakers to my enhanced direct/reflecting loudspeakers, it seems to me there is much to be said for having at least some of the sound, ok much of the sound being directed at the room surfaces and away from the listener. This is done in the AR9 at very low frequencies and in my installation at very high frequencies. If I were to "re-engineer" the speaker, I would add more of the same 8" and 1 1/2" drives to add reflected sound in the midrange.

The only drawback I see as far as AR's drivers are concerned is that they are no longer readily available. Trying to reverse engineer this speaker system using currently available drivers would likely be very challenging. Selecting a dome midrange IMO would be critical to the success of such an effort. So would designing a cabinet suitably sized for available drivers. The Tonegen 1259 would require approximately twice the volume. It should be considered in light of the fact that to a large extent, it was designed by people most familiar with and admiring of the AR 12" driver. The Bully 15" subwoofer Parts Express no. 297-150 either singly or in pairs might also be worth considering even though its Fs is 27 hz. With suitable equalization in a proper enclosure it can probably equal the performance of the AR 12" driver. Obviously, the crossover network would have to be redesigned from the ground up.

Link to comment
Share on other sites

Hi Steve F.

Thanks for your comments, just wondering if you've gone over your professional experience here at the site or somewhere I can read about it? Just like to know who I'm talking to before I comment. There are links to my informal speaker/audio page and professional page in my profile.

You mention marketing, I offer this for people to think about and have no plans for marketing. I make no claim to be solving new problems, this is a classic site, just offering something similar to a classic and yes some choices might be made just to follow the original when it makes sense. I do have some innovative ideas but I don't usually discuss them online.

Pete B.

Link to comment
Share on other sites

Guest radkrisdoc

Hi Pete!

Nice thread you have started here! I'd like to add a few suggestions to the choices you have there: a budget version of the Vifa XT tweeter is the Vifa DX25TG05-04. It is the XT without the phase plug, for a lot less and its got some good reviews I think.

My second suggestion would be the Visaton dome midrange, which is available at Solen. You can choose either a 4 ohm "ordinary" version or two 8 ohm "high end" versions. On the other hand, if you are looking at designing an 8 ohm speaker system, Scan Speak offers an upper midrange D3806/820000 (effective from 1.5 to 13 KHz).

The lower midrange or midbass as we call it now.....choosing an 8" midbass driver with the choices available seems a bit impractical mostly due to Vas considerations, I have yet to see a good 8" midbass designed to work from 200 Hz to 1200 Hz in an enclosure of around 3 litres with good total Q and an impedance of 4 ohms like the AR-9's 200027 LMR. All 8" drivers available now have a requirement of at least 8.5 to 15 litres. And there are no 4 ohm drivers, which is very disappointing. If you decide to design an 8 ohm system then there may be a few choices but you will still end up with a larger enclosure (the dedicated midbass enclosure that is).

I guess you can make the total enclosure volume smaller by choosing a good woofer, like the Peerless XLS which has lower Vas and will work well in a smaller volume.

As an ending note, I really want to try the Visaton midrange. I am still working on my AR-90's though and it will take me a fair amount of time to finish.

Link to comment
Share on other sites

Pete,

Your "ForA-9" Speaker Concept looks like the classic, "a solution for which there is no problem." Those fancy Vifa drivers are indeed beautiful devices, but they really don't do anything to the basic concept of the AR-9. In order to make a contribution in science, such as speaker design, one must first examine and understand the problem. Solutions then come much easier. The great loudspeaker engineers, such as those involved in the design of the AR-9, use the customary scientific method: carefully researching and examining the existing problems of loudspeaker design before putting pencil to paper. For example, when Edgar Villchur invented the acoustic-suspension woofer, he studied one of the biggest "problems" then associated with speaker design -- high distortion in the low bass -- and determined that the reason for this was non-linearity in the mechanical restoring force used for centering of woofers. Woofers could not make the long axial movement necessary to reproduce low bass without the suspensions getting into a bind, thus causing high distortion. Villchur did not set out to design a bookshelf speaker with powerful low bass with low distortion; his goal was to get at the problem of non-linearity in woofers. Once he saw that, the air spring came to him rather easily.

Not really trying to criticize here, but the question might be: are there any really serious problems in the AR-9 that would warrant an attempted re-design? Of course it is not perfect, but it was a very successful commercial design that has withstood the test of time. How many other designs such as this have a similar lineage?

--Tom Tyson

Link to comment
Share on other sites

The woofer section will be close to

>or below 4 ohms whereas the midranges are around 6 ohms and

>would have to be checked for voltage sensitivity to determine

>if they're suitable. Smaller versions of these drivers could

>be paired up in parallel if higher sensitivity is required.

So in other words, these drivers are in no way a parameter match for those in the original AR-9 design, and constitute a solution to a problem that does not exist.

>TWEETER:

>I suggested the Vifa 3/4" tweeter as an AR3a/LST replacement

>in response to those looking for a 2.75 ohm RDC tweeter. It

>seems to fit the AR-9 better from a look an feel point of view

>since the AR-9 is a newer and more modern design. The word

>out is that this .75" driver has excellent characteristics

>almost keeping up with many 1" domes.

What do "excellent characteristics" and "keeping up", mean? Is this an arcane "Unibox" parameter?

Please advise how you intend to replicate the Acoustic Blanket's effect, or at least why it wouldn't be necessary. Or something.

Link to comment
Share on other sites

Perhaps Pete's point was to design a speaker along the lines of AR 9 using available hardware that's off the shelf today. What is the problem with AR 9 that his design would solve? It's that the parts are no longer readily available and you must scrounge just to get the old parts with no guarantee that what you get will perform exactly as it did when it was manufactured. I would hope that about 20+ years after introduction of AR 9 and with the explosion of DIY and the proliferation of manufactured loudspeakers, the market would make alternatives available which could be assembled to give similar, equivalent, or even better results. I think far too much is being made of having to find a justification to design and build this project. AR 9 was and remains a very well conceived and executed engineered product, not a sacrosanct icon to be worshiped because it can never be substantially duplicated or improved upon. I for one like Pete's idea, I just don't agree with some of his suggested drivers as the best choices.

Link to comment
Share on other sites

>Perhaps Pete's point was to design a speaker along the lines

>of AR 9 using available hardware that's off the shelf today.

>What is the problem with AR 9 that his design would solve?

>It's that the parts are no longer readily available and you

>must scrounge just to get the old parts with no guarantee that

>what you get will perform exactly as it did when it was

>manufactured. I would hope that about 20+ years after

>introduction of AR 9 and with the explosion of DIY and the

>proliferation of manufactured loudspeakers, the market would

>make alternatives available which could be assembled to give

>similar, equivalent, or even better results. I think far too

>much is being made of having to find a justification to design

>and build this project. AR 9 was and remains a very well

>conceived and executed engineered product, not a sacrosanct

>icon to be worshiped because it can never be substantially

>duplicated or improved upon. I for one like Pete's idea, I

>just don't agree with some of his suggested drivers as the

>best choices.

Soundminded,

The AR-9 is not a "sacred cow," and no one is worshiping it. The point is that Pete's DIY idea is riding on the coattails of the AR-9, not on a unique design idea. It is trying to "improve on the AR-9," by virtue of its moniker, "ForA-9," rather than being a DIY of a fresh new design. This is not unlike the "Improved AR-3a" article that appeared in *AudioXPress* a few years ago: the writer worked tirelessly rewinding voice coils, changing magnets, modifying cones and so forth to make a better AR-3a. It was proclaimed a significant improvement by several people who heard it, but when it got to Joseph D'Appolito's testing facility, it was quite apparent that it had many problems and response aberrations. Basically, it did not solve any known problems with the AR-3a.

There is no reason to believe that a speaker consisting of Pete's expensive drivers couldn't be made to perform well, perhaps as good as or better than the original 27-year-old AR-9 design, and I suspect that Pete could design a fine speaker consisting of those OEM drivers. But it doesn't answer any questions to any fundamental problems. What, therefore, are the problems with the AR-9? Not enough bass? Too bright sounding? Current drivers are unavailable? Just by adding new woofers with greater X-max does not assure better bass response, as even those woofers may be non-linear in the given enclosure. Besides, how much more bass does one need? As far as using a ribbon tweeter, you could just about kiss dispersion goodby, as it would be far more directional. But those are minor quibbles: what are the real issues with the AR-9 that would warrant an attempted re-design? Does Pete have the wherewithal to accurately measure the performance of this new speaker to document that it is an actual improvement of the original AR-9? Remember, AR had the resources of a multi-million-dollar test lab and facilities developed over many years of designing top-flight loudspeakers, and the performance of the AR-9 was extensively documented. In the end, one might end up with a very, very expensive retro-AR-9 that cost a small fortune in parts, and that did not sound better (or perhaps even as good). Another thought: the AR-9 is very placement sensitive. Room acoustics play a very big part in the success or failure of that speaker's sound, so be sure that your room's acoustics are what they should be to get the most out of that speaker.

As for finding parts, eBay has parts for AR speakers being offered on a regular basis, and there does not seem to be a great shortage. One could even buy some poor-quality AR-9s or AR-90s for the parts alone, and the cost might be less than buying new Vifa tweeters and midrange drivers alone.

--Tom Tyson

Link to comment
Share on other sites

>The AR-9 is not a "sacred cow," and no one is worshiping it.

>The point is that Pete's DIY idea is riding on the coattails

>of the AR-9, not on a unique design idea. It is trying to

>"improve on the AR-9," by virtue of its moniker, "ForA-9,"

>rather than being a DIY of a fresh new design. This is not

>unlike the "Improved AR-3a" article that appeared in

>*AudioXPress* a few years ago: the writer worked tirelessly

>rewinding voice coils, changing magnets, modifying cones and

>so forth to make a better AR-3a. It was proclaimed a

>significant improvement by several people who heard it, but

>when it got to Joseph D'Appolito's testing facility, it was

>quite apparent that it had many problems and response

>aberrations. Basically, it did not solve any known problems

>with the AR-3a.

You are a killjoy. This is not about manufacturing a commercial product. It's about having fun in a DIY project, learning from looking at how someone else solved a problem and trying to outguess or outthink them for no other purpose than the fun of it. Immitation is the sincerest form of flattery. Of the countless thousands of designs he could have chosen to try to clone or better, look at which one he picked. I for one hope he tries it and lets us know how it works out and what he'd do differently if he'd take another shot at it. He apparantly has the experience and skill to make a serious effort. Go for it Pete!

>There is no reason to believe that a speaker consisting of

>Pete's expensive drivers couldn't be made to perform well,

>perhaps as good as or better than the original 27-year-old

>AR-9 design, and I suspect that Pete could design a fine

>speaker consisting of those OEM drivers. But it doesn't

>answer any questions to any fundamental problems. What,

>therefore, are the problems with the AR-9? Not enough bass?

>Too bright sounding? Current drivers are unavailable? Just

>by adding new woofers with greater X-max does not assure

>better bass response, as even those woofers may be non-linear

>in the given enclosure. Besides, how much more bass does one

>need?

There is the satisfaction of doing it yourself. That is reward enough and its own justification. Why do people build automobiles or airplanes from kits when they could just as easily go out and buy one? That's the big difference between a hobby and a profession.

As far as using a ribbon tweeter, you could just about

>kiss dispersion goodby, as it would be far more directional.

True. This would irreparably alter the concept. But for Pete, AR9 is a starting point, not necessarily a goal. He will build for his own satisfaction even if the results are by some criteria poorer than the paradyme. He'll go wherever his whims or ideas take him.

>But those are minor quibbles: what are the real issues with

>the AR-9 that would warrant an attempted re-design? Does Pete

>have the wherewithal to accurately measure the performance of

>this new speaker to document that it is an actual improvement

>of the original AR-9? Remember, AR had the resources of a

>multi-million-dollar test lab and facilities developed over

>many years of designing top-flight loudspeakers, and the

>performance of the AR-9 was extensively documented. In the

>end, one might end up with a very, very expensive retro-AR-9

>that cost a small fortune in parts, and that did not sound

>better (or perhaps even as good).

Point well taken. This is why most home brew designs almost always fail to equal well engineered commercial counterparts. This usually won't stop anyone. I've been fantasizing with just this futility myself along with several others including JBL Paragon D44000. Now that's another project and a half considering that by JBL's own account, of the approximately 1000 they built over about two decades, no two were exactly alike and no currently available plans exist.

Another thought: the AR-9

>is very placement sensitive. Room acoustics play a very big

>part in the success or failure of that speaker's sound, so be

>sure that your room's acoustics are what they should be to get

>the most out of that speaker.

I can attest to that from personal experience. Move the speaker a few inches and the lowest bass can all but disappear.

>As for finding parts, eBay has parts for AR speakers being

>offered on a regular basis, and there does not seem to be a

>great shortage. One could even buy some poor-quality AR-9s or

>AR-90s for the parts alone, and the cost might be less than

>buying new Vifa tweeters and midrange drivers alone.

True also although it can be an pain since the sources are usually unreliable. The very part you need is the one that is defective when it arrives. My hunch is that Pete wants to experiment with the concept, not build his own AR9. If that's all he wanted, it would be cheaper to just buy a pair. Occasionally they also appear on the market used, sometimes in excellent condition.

Lighten up Tom. This is a place people come to have fun, not debate the philosophy of why they should or shouldn't try something in their home workshop. For most of us, this is not our day job.

Link to comment
Share on other sites

Guest Barrydor

The AR9 was a very well executed design and probably one of the most tonally correct loudspeakers ever created. I have owned my AR9's for 26 years and until recently, I have yet to encounter anything priced in the realm of reasonableness (or not) that could equal their performance for long term listening enjoyment of the varieties of music I listen to

If I were redesigning the AR9 to improve performance and actually resolve problems, I would proceed as follows:

Placing the woofers on the side of the enclosure was done to get them close to the rear wall and therefore to place the wavelength of reflected bass energy above the woofer frequency. This requires that the speaker be placed close to the wall, which is not the best position for imaging. I would use bass EQ to enable correcting the bass response regardless of speaker position, perhaps using powered subwoofers to accomplish this

I would improve the integrity of the woofer enclosure to minimize enclosure radiation and verify the results with accelerometer testing of the enclosure. Perhaps the enclosure could be built using constrained layer damping and internal bracing to render enclosure resonance inaudible

For the upper frequency range, I would temporally align the drivers on their acoustical centers to ensure that the sound from all of the drivers reached the listener at the same time. I would keep the acoustic blanket to control reflection, but I also would narrow the upper enclosure as much as possible to minimize reflections

I would carefully design the upper driver section to control horizontal and vertical dispersion angle and establish a uniform angle over the frequency range. This would help to control floor, ceiling and sidewall reflections. This would require careful selection of the lower & upper midrange drivers as well as the tweeters

The material for the tweeter dome would have to be carefully selected and would have to be well damped. Soft domes (silk) often exhibit pistonic breakup modes in the audible range while metal domes often exhibit in-band and/or out of band ringing which needs to be controlled

For the crossover, I would use a first order design to ensure that all drivers are in phase over their frequency range and at the crossover points. This would require careful driver selection as each driver will be forced to produce out of band frequencies and therefore dissipate more power. This should not be a problem with modern driver technology

I would use transmission line loading for the drivers to flatten their impedance curve and help to ensure correct overall frequency response given that some frequency ranges will be reproduced by two drivers because of the first order crossover slope

I would use the best crossover components, internal wiring and binding posts I could find and I would solder the internal wiring directly to the driver terminals. No compromises on construction or components would be taken within the realm of reason

If I did my homework and accomplished this well, the result would be a speaker that is as tonally correct as the AR9 and is also time and phase correct over the entire audible frequency range. If you are thinking that I don't have to execute the redesign because I have described products that already exist, you are correct

Many competent speakers are very good tonally, but just about all of them make a total mess out of time and phase relationships. This may not be overly important in recordings where the relationships have already been corrupted by mixing and EQ, but I believe it is critical in maintaining the integrity of live recordings where minimal post processing has been used. I am surprised that more speaker manufacturers have not addressed the issue of time and phase relationships

After a lot of research, listening to many different speakers and attempting to understand room interactions (up to and including listening to speakers in a "semi-anechoic" outdoor environment, the results of which I posted on this forum), I have become convinced that it essential for a speaker to be time and phase correct in order to be musically accurate and involving

Added benefits of this type of design are better inteaction with the room, absence of listening fatigue and a rock solid image that extends across the listening area and does not exhibit a sweet spot. When you change your listening position, the instruments remain in the same place on the soundstage

I now believe that time and phase relationships are very audible and I know of a couple of audiophiles, including myself, who find it very difficult to listen for long to anything else, including the AR9, after they have heard a well executed time and phase correct loudspeaker. This is why if I was redesigning the AR9, I would make it a time and phase correct loudspeaker. In my opinion, it would then be very close to being a perfect transducer

My comments here are in no way a criticism of the AR9 or any other AR speaker. I always have and still do think the AR9 is one of the best speakers the world has ever seen. The technology, however, is over 20 years old. I would almost be willing to bet that if AR was still in business with the level of engineering they once had, they would be building time and phase correct loudspeakers today - they sure got everything else right

Barry

Link to comment
Share on other sites

>You are a killjoy. This is not about manufacturing a

>commercial product. It's about having fun in a DIY project,

>learning from looking at how someone else solved a problem and

>trying to outguess or outthink them for no other purpose than

>the fun of it.

Tom's replies have *always* been respectful and informative...he responded to a request for critical opinions with a critical opinion - that doesn't make him a "killjoy". It's a good bet that most of us have attempted loudspeaker projects in the past, and there's no argument in his post against that.

>There is the satisfaction of doing it yourself. That is

>reward enough and its own justification. Why do people build

>automobiles or airplanes from kits when they could just as

>easily go out and buy one? That's the big difference between

>a hobby and a profession.

No it isn't. The end result (how the finished product compares to an AR-9) is what counts, otherwise it's just vanity.

But for

>Pete, AR9 is a starting point, not necessarily a goal. He

>will build for his own satisfaction even if the results are by

>some criteria poorer than the paradyme. He'll go wherever his

>whims or ideas take him.

It's not a starting point when the project leaves behind the tenets set forth by the original designers. Anyone is free to abandon the *paradigm*, just don't pretend you're building a better AR-9.

>Lighten up Tom. This is a place people come to have fun, not

>debate the philosophy of why they should or shouldn't try

>something in their home workshop. For most of us, this is not

>our day job.

"Lighten up" is not a cogent response - it's disingenuous and condescending. Please go back and read his post more carefully, there's nothing in it that's been refuted.

Link to comment
Share on other sites

This has certainly turned into a wide-ranging topic, and it seems to have broken into two specific branches of thought, not necessarily related to each other.

Branch 1-The Engineering Rationale:

This train of thought puts forth the notion that the AR-9 was an extremely thoroughly-engineered product, very well thought out, a speaker that identified and solved several readily-identifiable technical issues. To arbitrarily re-do the speaker, willy-nilly, by picking out random drivers from various catalogs is not a good or worthwhile exercise. It is intellectually bankrupt, completely without a valid engineering premise, and no self-respecting professional engineer would ever approach a project this way. Only by identifying a set of specific engineering objectives can successful engineering solutions be developed. Without a tangible set of goals, there is no way to measure success.

Branch 2—The Hobbyist Rationale:

This train of thought presents the idea that having fun with audio equipment is what matters to a hobbyist. Do we have a specific goal in mind? Sure we do—the goal is to see if we can re-assemble a "9" using modern drivers in pretty much the same configuration as the original. That would be fun, and fun IS the goal of a hobby, isn’t it? So what if "real" companies don’t go about it this way. We’re a bunch of pretty well-informed enthusiasts, not the Director of Engineering for a major speaker company. Our objective is entertainment, with some self-satisfaction thrown in as we demonstrate some cleverness to ourselves. What’s wrong with that?

Both rationales are correct. Professional engineers would never re-do a product by leafing through a catalog and saying, "Hey, that looks like a pretty neat tweeter! I’ll try it." But that’s exactly how a hobbyist does things. Different people on this forum approach things from different vantage points, and we should endeavor to keep that in mind.

Steve F.

Link to comment
Share on other sites

An ambitious project, please let me know how I can help! You'll never quite make another AR9, but I don't think that's the point. Speaker building is fun, and there is much to be learned from the process. Who knows... maybe even a new "classic" speaker design will result.

http://ar.us.biz.yahoo.com/bw/050310/95961_1.html

http://stereophile.com/news/0301405tymphany/

Ken Kantor

kkantor@gmail.com

www.tymphany.com

www.aural.org

Link to comment
Share on other sites

Ken !

Does the breaking news mean you might be able to let-up a bit and come join-in the retro-fun?

So you've been to Denmark and all sorts of interesting places and come back with a displacement bigger'n your woofer. Congratulations on the take-over of, uh, I mean merger, with DTS.

I've thought of an advertising hook for you:

"Piston speaker goes 'boing, boing, boing, boing, boing, boing;'

Kantor speaker goes 'Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.'"

It's been done, nevermind.

I'm sure I'm not the only one wondering how scalable this invention is and about any other interesting sharable particulars.

Bret

Link to comment
Share on other sites

Why wouldn't you use a dome upper midrange driver? The problem of matching a 12" to a 1.5" dome is pretty-well eliminated by adding the lower midrange driver, isn't it?

Bret

Link to comment
Share on other sites

>AR did NOT say to themselves, "Let’s do a 4-way; now what drivers can we throw together?" See the difference?<

No, but AR seemed to say; "Hey, we've got experience with a tweeter like this, and a dome midrange like this. . . we'll tweak it like this. . . and now, because the dome isn't great in this sonic area we gotta stick a driver in between it and the woofer. . . and speaking of woofers, let's use the same woofer we've been using since the 50s and just make the cabinet bigger."

It isn't like they did a complete, new, redesign of absolutely everything.

I suspect if they had the 9 wouldn't be as special as it is. The familiarity helped.

Bret

Link to comment
Share on other sites

Thanks Soundminded,

We've disagreed in the past but you basically hit the nail on the head here. Replacement parts are hard to find and many of them are not drop in replacements as can be seen in the work I've done in trying to help with woofers, mids, and tweeters. Perhaps someone would like to build this system from scratch which was more of my intent. I don't know if I'll ever build this system, I'm in no rush, but I'd probably do it by using a beat up pair of AR-9s for a prototype. I would not suggest a complete rebuild of a good working pair.

Several others here rudely made assumptions, they didn't bother to ask my intentions, they assumed (incorrectly) and then claim that this is ill conceived. Their assumptions are wrong but I'm not going to get into a back and forth with them.

They erroneously claim that I should solve a new engineering problem, yet if I were to do that this would not be similar to the AR-9 since it would necessarily have some new innovation. It would go against my initial intent here. But here again they've assumed, how do they know my intent without asking? Perhaps I'd quad amp the system and use digital crossovers and digital room correction, they didn't ask. I'm not firm on how to proceed here and there could be many variations. I'm more likely to design closer to the original but I might move crossover frequencies, revoice, and/or use digital crossovers if I choose to do so. My intent is not to do a clone.

Let me rephrase my request for thoughts: constructive polite comments and questions please?

Pete B.

>Perhaps Pete's point was to design a speaker along the lines

>of AR 9 using available hardware that's off the shelf today.

>What is the problem with AR 9 that his design would solve?

>It's that the parts are no longer readily available and you

>must scrounge just to get the old parts with no guarantee that

>what you get will perform exactly as it did when it was

>manufactured. I would hope that about 20+ years after

>introduction of AR 9 and with the explosion of DIY and the

>proliferation of manufactured loudspeakers, the market would

>make alternatives available which could be assembled to give

>similar, equivalent, or even better results. I think far too

>much is being made of having to find a justification to design

>and build this project. AR 9 was and remains a very well

>conceived and executed engineered product, not a sacrosanct

>icon to be worshiped because it can never be substantially

>duplicated or improved upon. I for one like Pete's idea, I

>just don't agree with some of his suggested drivers as the

>best choices.

Link to comment
Share on other sites

ar pro,

You are the one who is arrogant, you do not know what my intentions or motivations are or what the outcome of this project will be before it is completed. It just so happens that Soundminded understands the motivations of a designer/builder yet you try to slam him. I'm not going to carry on here, please leave the thread if you have nothing good to say. The tone of your posts are offensive and have no technical content.

Pete B.

>

>

>>You are a killjoy. This is not about manufacturing a

>>commercial product. It's about having fun in a DIY project,

>>learning from looking at how someone else solved a problem

>and

>>trying to outguess or outthink them for no other purpose

>than

>>the fun of it.

>

>Tom's replies have *always* been respectful and

>informative...he responded to a request for critical opinions

>with a critical opinion - that doesn't make him a "killjoy".

>It's a good bet that most of us have attempted loudspeaker

>projects in the past, and there's no argument in his post

>against that.

>

>>There is the satisfaction of doing it yourself. That is

>>reward enough and its own justification. Why do people

>build

>>automobiles or airplanes from kits when they could just as

>>easily go out and buy one? That's the big difference

>between

>>a hobby and a profession.

>

>No it isn't. The end result (how the finished product compares

>to an AR-9) is what counts, otherwise it's just vanity.

>

>But for

>>Pete, AR9 is a starting point, not necessarily a goal. He

>>will build for his own satisfaction even if the results are

>by

>>some criteria poorer than the paradyme. He'll go wherever

>his

>>whims or ideas take him.

>

>It's not a starting point when the project leaves behind the

>tenets set forth by the original designers. Anyone is free to

>abandon the *paradigm*, just don't pretend you're building a

>better AR-9.

>

>

>>Lighten up Tom. This is a place people come to have fun,

>not

>>debate the philosophy of why they should or shouldn't try

>>something in their home workshop. For most of us, this is

>not

>>our day job.

>

>"Lighten up" is not a cogent response - it's disingenuous and

>condescending. Please go back and read his post more

>carefully, there's nothing in it that's been refuted.

>

Link to comment
Share on other sites

Barry,

Thanks for the constructive comments. I did first order systems years ago but have been doing higher order systems lately. I've been thinking of revisting them but did not intend it for this system. I've also done TLs in the past but did not intend to use them here. I'll give your comments more thought and see if I come up with any more comments.

Thanks again,

Pete B.

Link to comment
Share on other sites

Hi Kris,

Not interested in the Vifa 1" or the Visaton, I already commented in your UMD thread about domes, where I also pointed out the Scan 1.5". The killer dome out there is the 3" ATC but it's very expensive and probably too large for this application. The other leaders are Morel 2" and the discontinued Dynaudio 2". I'm just not interested, I've prefered and used small cone mids for more than 15 years.

I don't see your problem with the SEAS 8", I will resize the enclosure if necessary and I doubt it will be necessary. Have you done a simulation of it in 3 liters? Do you know Fc and Qtc for the AR 8" in the AR-9 enclosure?

Let us know how the Visaton works out, push it hard, many less robust mid domes have lead wire failure problems.

Pete B.

>Hi Pete!

>Nice thread you have started here! I'd like to add a few

>suggestions to the choices you have there: a budget version of

>the Vifa XT tweeter is the Vifa DX25TG05-04. It is the XT

>without the phase plug, for a lot less and its got some good

>reviews I think.

>

>My second suggestion would be the Visaton dome midrange, which

>is available at Solen. You can choose either a 4 ohm

>"ordinary" version or two 8 ohm "high end" versions. On the

>other hand, if you are looking at designing an 8 ohm speaker

>system, Scan Speak offers an upper midrange D3806/820000

>(effective from 1.5 to 13 KHz).

>

>The lower midrange or midbass as we call it now.....choosing

>an 8" midbass driver with the choices available seems a bit

>impractical mostly due to Vas considerations, I have yet to

>see a good 8" midbass designed to work from 200 Hz to 1200 Hz

>in an enclosure of around 3 litres with good total Q and an

>impedance of 4 ohms like the AR-9's 200027 LMR. All 8" drivers

>available now have a requirement of at least 8.5 to 15 litres.

>And there are no 4 ohm drivers, which is very disappointing.

>If you decide to design an 8 ohm system then there may be a

>few choices but you will still end up with a larger enclosure

>(the dedicated midbass enclosure that is).

>

>I guess you can make the total enclosure volume smaller by

>choosing a good woofer, like the Peerless XLS which has lower

>Vas and will work well in a smaller volume.

>

>As an ending note, I really want to try the Visaton midrange.

>I am still working on my AR-90's though and it will take me a

>fair amount of time to finish.

Link to comment
Share on other sites

Steve F,

I find your leaping assumptions and generalizations that you know how engineers and hobbyists think to be offensive. You don't know my intentions, or motivation. By the way I consider myself to be a professional engineer. How would you know how I select drivers? Perhaps it is the way you select them and you assume that I do the same. Why don't you leave the thread if you have no constructive comments or technical content to add. You come across as a writer who gets his technical information out of marketing literature. I'm not interested in your arrogant comments.

Pete B.

>This has certainly turned into a wide-ranging topic, and it

>seems to have broken into two specific branches of thought,

>not necessarily related to each other.

>

>Branch 1-The Engineering Rationale:

>This train of thought puts forth the notion that the AR-9 was

>an extremely thoroughly-engineered product, very well thought

>out, a speaker that identified and solved several

>readily-identifiable technical issues. To arbitrarily re-do

>the speaker, willy-nilly, by picking out random drivers from

>various catalogs is not a good or worthwhile exercise. It is

>intellectually bankrupt, completely without a valid

>engineering premise, and no self-respecting professional

>engineer would ever approach a project this way. Only by

>identifying a set of specific engineering objectives can

>successful engineering solutions be developed. Without a

>tangible set of goals, there is no way to measure success.

>

>Branch 2—The Hobbyist Rationale:

>This train of thought presents the idea that having fun with

>audio equipment is what matters to a hobbyist. Do we have a

>specific goal in mind? Sure we do—the goal is to see if we can

>re-assemble a "9" using modern drivers in pretty much the same

>configuration as the original. That would be fun, and fun IS

>the goal of a hobby, isn’t it? So what if "real" companies

>don’t go about it this way. We’re a bunch of pretty

>well-informed enthusiasts, not the Director of Engineering for

>a major speaker company. Our objective is entertainment, with

>some self-satisfaction thrown in as we demonstrate some

>cleverness to ourselves. What’s wrong with that?

>

>Both rationales are correct. Professional engineers would

>never re-do a product by leafing through a catalog and saying,

>"Hey, that looks like a pretty neat tweeter! I’ll try it." But

>that’s exactly how a hobbyist does things. Different people on

>this forum approach things from different vantage points, and

>we should endeavor to keep that in mind.

>

>Steve F.

>

Link to comment
Share on other sites

Thanks for your support Ken,

Would you happen to have or know where we can find driver measurements for any of the drivers?

Pete B.

>An ambitious project, please let me know how I can help!

>You'll never quite make another AR9, but I don't think that's

>the point. Speaker building is fun, and there is much to be

>learned from the process. Who knows... maybe even a new

>"classic" speaker design will result.

>

>http://ar.us.biz.yahoo.com/bw/050310/95961_1.html

>

>http://stereophile.com/news/0301405tymphany/

>

>

>Ken Kantor

>

>kkantor@gmail.com

>

>www.tymphany.com

>

>www.aural.org

Link to comment
Share on other sites

Hi Bret,

I explained in Kris' UMD thread that small cone drivers provide much more VD and often have as good if not better dispersion because the dust cap acts as the radiator at high frequencies. This is supported by the fact that there are not many mid dome drivers available, only one 1.5" that I know of. There is little demand for them.

Pete B.

>Why wouldn't you use a dome upper midrange driver? The

>problem of matching a 12" to a 1.5" dome is pretty-well

>eliminated by adding the lower midrange driver, isn't it?

>

>Bret

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.


×
×
  • Create New...