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Musings on the AR-2ax crossover


Mach3

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With the significant level difference between the mid and the tweeter, it isn't clear that the dome adds much to the top Octave power response. Again, this is seen in Steve's [actually AR's, not "mine"] curves where the axial differences between mid and tweeter output are pretty well duplicated in the power response curve.

Regards,

David S.

Another takeaway from all this is the remarkable honesty and accuracy of AR's published curves in that time period. They showed you exactly what their speakers did, exactly how they performed.

I had "new" 2ax's, purchased in Feb 1972. I could clearly hear the tweeter, no problem. (Ah, 17 year-old ears!) I remember AR's advice was to use FM interstation white noise and adjust the M-T level controls until the source of the sound seemed like it was coming equally from both drivers.

High Fidelity magazine's test report suggested the tweeter at Max and the mid between Norm and Max.

Steve F.

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Another takeaway from all this is the remarkable honesty and accuracy of AR's published curves in that time period. They showed you exactly what their speakers did, exactly how they performed.

Very true. The only reason why we can have these discussions about the "crude" or "elegantly simple" (depending on your point of view) crossover networks of the early AR speakers is that they were good enough and AR's integrity was high enough that they were willing to publish honest curves (at least 2pi, smooth baffle, individual driver curves).

High Fidelity magazine's test report suggested the tweeter at Max and the mid between Norm and Max.

That seems to be the general consensus, and is inline with the measured performance.

David S.

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Been away the last week.

To some of the comments.

My original statement regarding the AR-2ax crossover was "....in fact it is surprisingly crude (or sophisticated depending on your perspective). Does anybody bother to actually read any longer? Or do we just react to the first thing we see that might deny our already conceived conclusions? Jeez Louise - there are several ways to analyse any circuit - in this age of minimal approaches the AR-2ax crossover could be viewed as extremely sophisiticated - first order, minimal phase, et cetera. Or just darn crude.

Maybe Occam was correct - the best answer is always the simplest ;-)).

Mr. Tyson - and I am quoting you here; Incidentally, the fiberglass on top of the midrange is for damping purposes, not "to suppress break up sounds when the mid is being sent frequencies that are beyond its ability to play." Please think about this statement for a moment - how does "damping purposes" differ from "suppressing break up sounds"? Answer me that one - for I think we are saying the same thing simply using different language. Perhaps the point was to demonstrate your superiority in all things stereo? So great - you are superior. Freely granted. Enjoy your principate.

Not only do I read every issue of TAShole and Stereofool, I also go to shows and have acquaintances with mega-buck systems. Within the constraints of being a human who is subjective I consider the sound produced by "old" and "crude" AR speakers to be vastly superior to most of the "uber" speakers currently available. Having heard Wilson, Focal, Artemis, Magico, Revel, et al I can honestly say that in terms of listening and enjoying MUSIC the AR species (particularly the MIGHTY NINE) gives up NOTHING to these $60k wonders. In fact I find most modern speakers to be rather thin sounding (no warmth), tending towards shrill and analytical. Though I must admit that the modern speakers are more coherent (the crossover seams are less obtrusive) and are definitely lower in "self noise" (particularly the Wilson models).

Of course this preference may be nothing more than a prejudice towards the "sound of AR". Who knows for sure? Humans are subjective particularly in regards our emotional responses to music. Let us not forget that Stravinsky was booed during the initial performance of "Le Sacre" and a riot followed - this from music lovers.

Having spent most of my working life as an engineer I can assure everybody that any manufacturing process that produces a product with a lower tolerance deviation is in fact a superior product. Simply spend some time with the work of W. Edwards Deming to better appreciate this fact. Significant tolerance deviation is an indication of a manufacturing process that is out of control - or that has not reached optimum conditions.

You do not build a better product by measuring - you measure to find out where your deviations are arising and then you drive the steps that lead the deviation to be "in control". My 1% deviation capacitors are indicative of a better product. A case has been made that some capacitors, e.g. Mundorf Silver/Oil, sound "better" than lesser polypropolene films - maybe they do. Maybe they don't.

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My 1% deviation capacitors are indicative of a better product. A case has been made that some capacitors, e.g. Mundorf Silver/Oil, sound "better" than lesser polypropolene films - maybe they do. Maybe they don't.

If you think Solen has a special line manufacturing higher quality 1% caps, you are kidding yourself. These caps seldom vary by more than that to begin with. It is just another way to squeeze another buck out of neurotic "audiophiles".

Roy

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If you think Solen has a special line manufacturing higher quality 1% caps, you are kidding yourself. These caps seldom vary by more than that to begin with. It is just another way to squeeze another buck out of neurotic "audiophiles".

Tolerances on most electronic components (capacitors, resistors, etc.) are established by measuring. At some point in the manufacturing line, automatic test equipment measures their actual values and depending on the results routes them to appropriate paths for 1%, 5%, 10%, Reject, etc. Then they are marked accordingly, either by stamping or with pre-marked plastic wraps.

In more complicated semiconductors such as ICs, test results may actually determine what model number the product is sold under. A 3.0GHz CPU is often identical to the 4.0GHz version of the same model except that it passed stability testing at 3.0GHz but failed at 4.0GHz. Changing a single connection in the packaging stage is enough to change its CPUID and then its case is stamped.

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I agree, my friend has a very expensive newer set up with bw speakers that must weigh 70 lbs a piece, the sound is detailed but not warm and a little overdone in the highs, I like my A25s more amazingly my system is not worth nearly as much money. Also it seems quality is some what lost on format, people seem to care less about sound quality because it's more about how many mp3's can be put on your phone. Have not seen a company that is willing to give the same quality components as yesteryear, seems to be more about marketing and engineering rather then both engineering and good components

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My original statement regarding the AR-2ax crossover was "....in fact it is surprisingly crude (or sophisticated depending on your perspective). Does anybody bother to actually read any longer? Or do we just react to the first thing we see that might deny our already conceived conclusions? Jeez Louise - there are several ways to analyse any circuit - in this age of minimal approaches the AR-2ax crossover could be viewed as extremely sophisiticated - first order, minimal phase, et cetera. Or just darn crude.

Maybe Occam was correct - the best answer is always the simplest ;-)).

Mr. Tyson - and I am quoting you here; Incidentally, the fiberglass on top of the midrange is for damping purposes, not "to suppress break up sounds when the mid is being sent frequencies that are beyond its ability to play." Please think about this statement for a moment - how does "damping purposes" differ from "suppressing break up sounds"? Answer me that one - for I think we are saying the same thing simply using different language. Perhaps the point was to demonstrate your superiority in all things stereo? So great - you are superior. Freely granted. Enjoy your principate.

It's obvious that I struck a nerve here—probably with more than one person. I think Mach3 took my comments personally, and that was not my intention. My intention was to say that these AR-2ax comments were flip and ill-expressed, and those comments and remarks clearly showed that Mach3 was unclear of the design purpose of the early AR speakers. The word "crude" means a lot of things, but usually it is used in a derogatory sense, such as "unrefined," "rough," "blunt" or even in some cases "offensive." Maybe Mach3 didn't mean it in a derogatory sense, but the word "crude" does not describe the AR-4x or AR-2ax crossover. "Basic" or "Simple" might be a better way to describe it, but it was nevertheless purposely simplistic.

"…to suppress break up sounds when the mid is being sent frequencies that are beyond its ability to play." Yes, the fiberglass on top of the driver was put there to smooth the output of the driver by adding damping to the driver. My complaint with Mach3's wording was this "being sent frequencies that are beyond its ability to play." What frequencies would those be, and what does that mean? Does Mach3 think that the fiberglass will "pad" down the output of the driver and block it from playing sounds sent to it that it was not supposed to reproduce? Once past the level control, that driver was allowed to play full output the high frequencies with a natural rolloff; in fact, the driver was used as a tweeter on the AR-4 and the AR-2x, so there was no need to "suppress frequencies that are beyond its ability to play."

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The term "crude" when applied to engineering efforts is a kind of perjorative that requires a great deal of knowledge about the problem being addressed and the alternatives available to solve it, not to mention the results. For example, the complex passive crossover networks in many modern speakers to equalize their frequency response compared to far simpler passive networks used in combination with multi-amplification, active crossovers and active equalization is crude, clumsy, and relatively ineffective. When the second method can easily and reliably adjust the system response in increments of 0.1 db every sixth of an octave and where there is no effect by changes in the load that alters the filter's response compared to what happens in a passive network the term crude is turned on its head. It's the modern speaker that's crude. The very concept of trying to adjust the low end response of a speaker using tuned ports where spring constant is a function of frequency (in Newton's second law of motion that governs speakers) when an alternative that is not frequency selective in this regard, namely the acoustic suspension principle is available again demonstrates just how truely crude in concept modern speakers are. The fact that the overwhelming majority of speakers designed using "modern" concepts produce unconvincing results IMO demonstrates a reversion to a cruder way of lookiing at things.

BTW, insofar as Demming is concerned, the better quality control of one manufacturing process over another only results in a superior product when all other things are equal. The poorly conceived product that is excellently manufactured cannot compete against the far better conceived product that is only manufactured to normal standards. Therefore the finest horse drawn carriage in the world is not match for a Volkswagon Beetle.

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Soundminded - your opinion is my point - in spite of simplistic, on the surface crude, mass-production techniques used by AR the resulting product was, in many, many ways, vastly superior to what is currently available for orders of magnitude more money.

I could not agree with you more in regards the inferior sound and performance of modern bass-reflex speakers - they huff, they puff and their bass is an indistinct rumble at best (and ALL modern boxes - save Magico - are vented enclosures). Alon Wolf, the Magico designer, has publicly stated that the reason modern speaker builders all use vented enclosures is simply because it is cheaper.

As for the vaunted "transparency" and "clarity" of modern designs? Mostly this is attributable, at least imo, to the fact that their lower three octaves are for the most part "Missing In Action". An old trick that PA systems use to enhance their so-called clarity is to drop the range of 100 Hz to 300 Hz about 3 dB - which is what most modern designs seem to do.

Now turning to Deming - I am not sure of your point. But having worked with traditional approaches to QC and having led the effort to replace these with Deming techniques I can assure you that the Deming approach is vastly superior. In essence Deming calls for the abadonment of QC measuring all together. Rather than have a tolerance find out why your process cannot make the part or do the work without any tolerance and then do so. If you want a hole drilled that is 0.050" wide do not accept any tolerance, e.g. 0.050" +/- 0.002", but rather spend your efforts on determining why your drill press cannot drill a hole that is exactly 0.050" every time. This inevitably leads to work on the drill press and associated tooling - but the end result is a work process that has NO TOLERANCE. And your quality control becomes absolute. Which is why Deming is so honored in Japan - for that is what they do.

As to whether or not the low-tolerance Solen caps are simply those that measured better or are the result of a better process I cannot say with absolute accuracy. But I would wager that those particular parts are the result of a better process not merely measuring the parts from a common line. Solen is not a company that is known for building shoddy parts.

As for Volkswagens - oh a love/hate relationship for myself. Worked on them for years (mechanic while getting my under grad degree) - and I can tell you that those cars were beyond crude - almost stone age in their design and manufacture. But for some reason, though totally unsafe (at any speed), incredibly crudely designed and built, prone to early failure (clutch gone at 30k miles, engine out for valve job at 20k, rod bearings failing by 50k miles) I did love the things. Wouldn't even think about driving one in todays traffic - but I crossed the country several times in one and truly loved their simplicity. Much like a Harley Davidson from the '60s and '70s - mechanical junk but for some reason really entrancing vehicles.

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As to whether or not the low-tolerance Solen caps are simply those that measured better or are the result of a better process I cannot say with absolute accuracy. But I would wager that those particular parts are the result of a better process not merely measuring the parts from a common line. Solen is not a company that is known for building shoddy parts.

I am not intimately familiar with what goes on at the Solen manufacturing facility, but the automated manufacturing and test process I described is universal, and it is a fairly safe bet that if they have two lines that are physically identical and have the same internal specs with tolerance being the only difference, then that is exactly what is going on. If, OTOH, their brand marketing strategy is to make 1% caps and nothing else, then the methodology is still the same and everything that doesn't make the cut at 1% is being directed to the "Reject" bin.

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Think you guys are getting a little emotional (irrational) and sometimes off-topic. That said, I may as well put in my 2 cents.

With perspective, the AR2ax (yes, i owned a pair) was a nice speaker to listen to at the time. If I rembember correctly, ALL AR speakers of that era had tweeters that at it's "maximum output" was still significantly lower than the midrange output. Intended or not, this yeilded the "concert hall slope" power response that IMO "classical music" lovers on these pages love so much.

But I do think the term "crude" is a little harsh; "simple" is more appropriate. And just because it's "simple" does not automatically imply "inferior" (or vice versa) ! I do know that "complex" can translate to "costlier" whether you like the end result or not.

Anyone with manufacturing / design experiance knows about "build-up of tolerances". More parts used to reach a specified "performance target", the more likely one can deviate from the target unless tolerances are "tight". The more drivers and X-O circuitry inside a given cabinet, the more costly AND more likely "performance" will deviate from the "refeference " This is true regardless of make,model, and vintage.

For the "target consumer" AR marketed it's products too, I think they did a good job of toeing the line between "performance", "reliability", "manufacturing cost", "unit -to-unit consistincy" and "customer satisfation".

As to what "good performance" is, that's up to the individual. I can say this with certainty though.The "vintage" AR's of the 60's and early 70's sound VERY "different" to the Teleydyne AR's (AR 9, 10pi, 11 etc.). Assuming you think the Teleydyne AR's "better" than the "vintage" AR's, you CANNOT get Teledyne performance using "simple" x-o's. At least not consistantly, and without driver failure using today's high -powered/ low cost amps/recievers.

You will have to pardon my grammar and spelling. A writer I am not ! But I DO know SOMETHING about designing and manufacturing speakers in the "real world". The "hobbyiest" along with some "professionals" (like me) usually have a VERY different perspective as to what is "good".

As an audio enthusiast, I know what I like and why.But as designer, I must make, many "guestimates" or assumptions about who's going to be using my finished product. What music will they be playing ? How loud ? Cheap or "quality" electonics. Room size ? Placement ? Can't speak for other designers but I've found this decision making process exhausting. Gotta keep the customer "happy" and still be "profitable".

I heard a very long time ago this statement: "Anybody can be a "critic". But can the people who disagree with the "critics" do better?

True then, true today.

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<<As to whether or not the low-tolerance Solen caps are simply those that measured better or are the result of a better process I cannot say with absolute accuracy. But I would wager that those particular parts are the result of a better process not merely measuring the parts from a common line. Solen is not a company that is known for building shoddy parts.>>

I've been purchasing speaker repair parts for over 35 years, and it is common practice for purveyors to measure and match capacitor tolerances for a fee. I have measured many caps over that period of time.

Another example of a "1%" alternative would be the excellent Dayton film caps sold by Parts Express. Once again, the 5% Daytons seldom vary by little more than 1%, if at all.

http://www.parts-exp...citor-index.cfm

Mach3, A better investment would be to purchase an inexpensive capacitance meter. You will be better informed, and have more fun. ;)

Roy

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To Soundminded

"It's the modern speaker that's crude. The very concept of trying to adjust the low end response of a speaker using tuned ports where spring constant is a function of frequency (in Newton's second law of motion that governs speakers) when an alternative that is not frequency selective in this regard, namely the acoustic suspension principle is available again demonstrates just how truely crude in concept modern speakers are. The fact that the overwhelming majority of speakers designed using "modern" concepts produce unconvincing results IMO demonstrates a reversion to a cruder way of lookiing at things."

I have to disagree here. When the "vintage" AR's were made, there was little understanding of ported designs.Then came Theile and Small. Their work made it possible for designers to theoretically model ported designs accurately before building them. Today, there are many "alignments" that's virtually indistinquishable from a sealed equivalent (when using blind A/B listening/testing using the same source material).

And, just because it's a sealed system DOES NOT means the bass is automatically "better". The AR "vintage" era (AR3a's, etc) and the "modern" Teleydyne AR era (AR 9, 10, etc.) both employ "sealed systems". But they can sound very different because of the system "Q". Take a sealed system with a very high (under-damped) "system Q" and you can "mimic" the "boom" often found in the very early "trial & error" ported systems.

It's been long established what the "trade-offs" are between sealed and vented designs. If you want very high undistorted SPL below 50 hz, I suppose you CAN do it with a sealed system. BUT, the enclosure(s) would be HUGE compaired to a properly tuned (alignment) ported system.

Granted, there are many "bad sounding" ported designs today. The question is this: Is it "bad" because the designer didn't know the science behind it? Or, is it "bad" because the designer knew the "target audience's" preferred sonic charateristics in the bass region and designed accordingly.

Properly executed ported systems of today are more "science" than the "art approach" employed during the early years of "hi-fi". That's why virtually all of todays subwoofers are ported. To do a "sealed equivalent" would require a much larger box with greatly reduced sensitivity (and subsequent need for larger amplifiers).

I supposs if I had unlimited funds, room space, no neighbors AND truly believed that the AR 3a's "bass signature" is the "holy grail" for bass reproduction for ALL kinds of music played in ALL kinds of enviroments, I would take the multiple AR3a (or the original AR 3) approach.

However, I would probably then be called an "elitetist", which I am not. I'm an audiophile with some technical knowledge, along with about a decade of practical design experience in the loudspeaker industry.

And, most of all, I consider myself "pragmatic" .

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. The very concept of trying to adjust the low end response of a speaker using tuned ports where spring constant is a function of frequency (in Newton's second law of motion that governs speakers) when an alternative that is not frequency selective in this regard, namely the acoustic suspension principle is available again demonstrates just how truely crude in concept modern speakers are. The fact that the overwhelming majority of speakers designed using "modern" concepts produce unconvincing results IMO demonstrates a reversion to a cruder way of lookiing at things.

Good to see Newton's second law of motion getting a plug (Acceleration is proportional to force) but what about the poor first and third? A body in motion tends to continue in a straight line (first law) must apply to woofer excursion and forces are balanced by equal and opposite reaction forces (third law) must apply everywhere (cone force on the air and vice versa, coil force on the magnet structure and vice versa, etc.)

Please explain how the tuned port has a spring constant that is a function of frequency? The slug of air in the port works aginst box stiffness, the same box stifness that is used for acoustic suspension. All of the electrical equivalent circuits work quite well with simple lumped parameters and no frequency dependent terms.

David S.

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GerryS,

Unfortunately I disagree with most of what you stated in regards the never-ending debate of sealed versus ported bass enclosures.

To wit:

Almost ALL of todays SOTA subwoofers (Paradigm, Velodyne, Carter, Martin-Logan, JL Audio) offer sealed enclosures. Why? Two main reasons - the advent of the cheap Class D amplifier allowing the designer to force the driver to perform (thus eliminating the need for huge enclosures which only serve to lower the spring rate of the air), and two the transient response of a sealed enclosure is far better than an equivalent ported box.

Theile-Small parameters do not change the physics of a vented enclosure; enormous group delay, huffing and chuffing of the port, and a tendency towards one-note sound. All Theile-Small does is allow the designer to better match a given driver to a given box - and of course the effect of the port size.

As to your claim of a DBT that demonstrated that listeners could not tell the difference between sealed and ported designs; that is one I would like to read - can you provide me a reference to this report? Because nobody I know has ever heard of such a study.

As for the effects of system Q on the sound of a sealed enclosure? I would highly recommend that you read Terry Holl's comments (Holl designed the AR-9) on how he worked with Q in his design - but Holl's main concern was NOT on the sonics surrounding modifying system Q - but rather on protecting the flimsy amplifiers of that period from the effects of the low impedance at the resonant point - Holl's design comments can be found on this site. I think you are somewhat wide of the mark in your understanding of Q and of box size in terms of a sealed enclosure (go look at the size of those sealed subwoofers from the top-line manufacturers I mentioned - they are all rather small boxes with the Carter offering being almost less than a single cubic foot).

For my taste there is no "trade off" between a ported and a sealed design - other than cost. If you want cheap and do not mind muddy bass go with the port. If you want accuracy go with the sealed box (of course the sealed box approach requires a LOT more power as well). But sealed boxes have always been the ticket for those who prize accuracy in music reproduction.

In my opinion the best bass available can be found in an AR-9 - at least the best bass available short of a Magico Q3 or Q5 - or one of the subwoofers I listed earlier in this message. As for the bass in a Wilson or Revel (with their ports) you will not be getting anything worth speaking of.

I too enjoy music tremendously - haven't built any speakers but what does that have to do with anything? I know guys who have built aircraft for thirty years and such doesn't give them any particular insight into the science and art of aircraft design.

So I guess we are just on opposite sides of the fence in this debate.

Enjoy the Music

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GerryS,

Unfortunately I disagree with most of what you stated in regards the never-ending debate of sealed versus ported bass enclosures.

To wit:

Almost ALL of todays SOTA subwoofers (Paradigm, Velodyne, Carter, Martin-Logan, JL Audio) offer sealed enclosures. Why? Two main reasons - the advent of the cheap Class D amplifier allowing the designer to force the driver to perform (thus eliminating the need for huge enclosures which only serve to lower the spring rate of the air), and two the transient response of a sealed enclosure is far better than an equivalent ported box.

Theile-Small parameters do not change the physics of a vented enclosure; enormous group delay, huffing and chuffing of the port, and a tendency towards one-note sound. All Theile-Small does is allow the designer to better match a given driver to a given box - and of course the effect of the port size.

As to your claim of a DBT that demonstrated that listeners could not tell the difference between sealed and ported designs; that is one I would like to read - can you provide me a reference to this report? Because nobody I know has ever heard of such a study.

As for the effects of system Q on the sound of a sealed enclosure? I would highly recommend that you read Terry Holl's comments (Holl designed the AR-9) on how he worked with Q in his design - but Holl's main concern was NOT on the sonics surrounding modifying system Q - but rather on protecting the flimsy amplifiers of that period from the effects of the low impedance at the resonant point - Holl's design comments can be found on this site. I think you are somewhat wide of the mark in your understanding of Q and of box size in terms of a sealed enclosure (go look at the size of those sealed subwoofers from the top-line manufacturers I mentioned - they are all rather small boxes with the Carter offering being almost less than a single cubic foot).

For my taste there is no "trade off" between a ported and a sealed design - other than cost. If you want cheap and do not mind muddy bass go with the port. If you want accuracy go with the sealed box (of course the sealed box approach requires a LOT more power as well). But sealed boxes have always been the ticket for those who prize accuracy in music reproduction.

In my opinion the best bass available can be found in an AR-9 - at least the best bass available short of a Magico Q3 or Q5 - or one of the subwoofers I listed earlier in this message. As for the bass in a Wilson or Revel (with their ports) you will not be getting anything worth speaking of.

I too enjoy music tremendously - haven't built any speakers but what does that have to do with anything? I know guys who have built aircraft for thirty years and such doesn't give them any particular insight into the science and art of aircraft design.

So I guess we are just on opposite sides of the fence in this debate.

Enjoy the Music

"For my taste there is no "trade off" between a ported and a sealed design - other than cost".

Can't speak for the rest reading this forum, but "cost" for ME is THE top priority when making a purchase (audio or otherwise). Since I don't have the finances to attain perfection at any price, VALUE is extremely important.

As for the merits of sealed vs vented, which is "better" for me isn't really a "debate". it's more about sonic preference. Sonic prefernce depends a lot on my age, enviroment, source material, music genre and the "vintage" of the recordings I tend to listen too. In your own words, "for my taste..." ! My musical taste tends to be very broad; rock in all it's forms, jazz, folk, classics, and (shudder) disco !

"All things being equal" is something that's often quoted in general terms. But in the "real world", I've NEVER found this to be true. ALL products that I know of involves inevitable "tradeoffs" or "compromises"...laws of physics and economics.

Someday and magically, I'd like to see a SINGLE automobile that is inifinately fast, consumes no fuel, self -parking, stop on a dime, carry twenty passengers when needed AND "handle" like the best sports car. Might as well add "affordable to all" . Not gonna happen; with cars OR speakers.

As to the BLT between "ported vs sealed", it was done informally some years back and never a "formal study" that got published. We were VERY careful that both systems were "level matched" as best as possible, and that neither was "over-driven". What I DO distincly remember is this. Depending on program material used, there were several trials where one could not tell one from the other. Further trials using a variety of genres AND containg different "bass heavy", we as a group found it impossible to decide which was the "clear winner".

Which leads me to the my next point: "accuracy". I will have to take your word about the one cubic foot sealed box SOTA designs you mentioned. Way out of my price range, but that's really moot. The "relevant" question is this: Can a sealed one cubic foot box driven to it's max reproduce sufficient SPL "accurately" ? Depends on what you deem "accurate".

Play chamber music @ low levels in a relatively small room, the system (ported or sealed) will probably remain "linear". Play something with huge dynamic range @ very low frequencies in a "medium sized room", and I asssure you it will no longer be "accurate". Sealed systems may not "chuff" like a ported system of similar size. But It WILL suffer other problems like dynamic compression.

Speaking of "transient response". Many advocates of the sealed box approach (I believe this includes Roy Allison) think the term meaningless when applied to bass reprodution. Bass frequencies by their nature have long wavelengths and a relatively sustained time period before it "decays". By comparison, midrange & treble DO contain "transients" (very high levels of intensity but very short in duration). Speaking of "transient response" at bass frequencies makes as much sense as saying tweeters providing a "room-shaking viceral experience".

I've never owned a product that was truly "high -end" and "prestigious" like the ones you mentioned. But I have listened to them. Some are GREAT products. But LOTS were IMO expensive "eye candy" for wealthy people.One of my most expensive single product ever purchase was a Dunlap-Clarke Dreadought 1000 power amp; $1500 in the 70's. Bought it to drive my AR 10Pi's . I've never owned the more adavanced amps of today (Bash, Class H, etc) so can't say if they will "stand up" compaired to the "brute force" amps of the 70's and 80's.

On a related note, my friend Poh Ser Hsu (of Hsu Research) firmly believes that "subwoofers" aren't "real" subwoofers unless they can reproduce bass down to around 16 hz @ "realistic levels". As good as the AR 9 is at reproducing bass, it too will become "non-linear" tryng to reproduce organ notes at "realistic" ("accurate") levels. Poh Ser recently gave me one of his "mid-level" subwoofer products as a gift: A "VTF2 Mark 4 "

With this product,one can choose "low frequencie extension" or "punch" (but not both simultainiously). It has a self-contained 250 watt "bash-type" amp and a very flexible electronic crossover as well. But at 70 pounds, it remains "boxed". Because my listening habits have changed over the years, I've "mellowed" and now have other interest besides audio. And I don't want to hurt my back (again) moving loudspeakers.

IMO, if you don't constantly move loudspeakers and furniture, your'e not a "real audiophile" (or at least an educated one)!

So I visit this site and post on it occasionally. But not to debate. Mostly for nostalgia !

Enjoy the music !

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Jeez Louise where to start?

I guess first and foremost is the fact that transient response is critical to a well designed bass system - drums do "snap" and have a rapid decay rate - with a ported design which is sending a wave front 180 degrees out-of-phase with the real signal (after all it is the back wave that is going out that hole) there are real problems with bass transient response.

As for all those SOTA products? Unfortunately I don't own any of them - cannot afford them. But I have heard ALL of them in various places (shows, dealers, friends). The Carver bass box (~ 1 cubic foot) goes for around $2.5k per - still too much for me. But the point is that he is getting deep bass from a small box (with a huge Class D amp wrestling that sealed box cone into place). BTW: Carver is able to achieve this with vanishingly low levels of distortion.

I have never heard a Hsu system - but I HAVE heard very good things about them - reputedly one of the best designs around. I notice from his web site that he offers a system that can function either as a ported box or a sealed box - interesting. He seems to get good response both ways - and his prices are pretty nice.

As for the AR-9 - it is pretty much done around 30 Hz - the literature reports 28Hz but I don't think I can get that low - nevertheless as you point out it is enough for my taste (and most importantly I can afford it). If you want a real test for bass response try track 1 of "The Dark Knight" sound track. Some real low stuff there. The 9 will play all of this track but at much reduced volumes.

I too owned a set of 10pi speakers (in 1979) - a wonderful speaker that I thought was a great improvement over the AR-3a. Wish I still had them.

I will close by noting that I never move either the furniture or my speakers - I guess I am no audiophile - fine by me. I just love music and the gear is only something that allows me to access it.

best to you,

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Jeez Louise where to start?

I guess first and foremost is the fact that transient response is critical to a well designed bass system - drums do "snap" and have a rapid decay rate - with a ported design which is sending a wave front 180 degrees out-of-phase with the real signal (after all it is the back wave that is going out that hole) there are real problems with bass transient response.

As for all those SOTA products? Unfortunately I don't own any of them - cannot afford them. But I have heard ALL of them in various places (shows, dealers, friends). The Carver bass box (~ 1 cubic foot) goes for around $2.5k per - still too much for me. But the point is that he is getting deep bass from a small box (with a huge Class D amp wrestling that sealed box cone into place). BTW: Carver is able to achieve this with vanishingly low levels of distortion.

I have never heard a Hsu system - but I HAVE heard very good things about them - reputedly one of the best designs around. I notice from his web site that he offers a system that can function either as a ported box or a sealed box - interesting. He seems to get good response both ways - and his prices are pretty nice.

As for the AR-9 - it is pretty much done around 30 Hz - the literature reports 28Hz but I don't think I can get that low - nevertheless as you point out it is enough for my taste (and most importantly I can afford it). If you want a real test for bass response try track 1 of "The Dark Knight" sound track. Some real low stuff there. The 9 will play all of this track but at much reduced volumes.

I too owned a set of 10pi speakers (in 1979) - a wonderful speaker that I thought was a great improvement over the AR-3a. Wish I still had them.

I will close by noting that I never move either the furniture or my speakers - I guess I am no audiophile - fine by me. I just love music and the gear is only something that allows me to access it.

best to you,

Tried researching " bass transient response" and could find no definitive answer.SO many opinions ("expert" or otherwise) on this subject. My personal belief is that the "snap" on bass drums is the higher order harmonics being generated. I could be wrong !

Did come across this though( never heard of this guy so don't know of his qualifications/credentials). Decide for yourself.

And good listening.... best to you as well !!!!!!

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Sub-30Hz Behavior

Sealed box designs and single-reflex bandpasses are much better at controlling excursion at extremely low-frequencies (below 30Hz.) For this reason, they can usually handle more power in these frequency ranges than ported designs and dual-reflex bandpass designs which makes them less prone to low-frequency induced speaker damage. At frequencies below the tuning frequency of the port, a woofer in a ported box (or a dual-reflex bandpass) starts to de-couple. This means that the controlling function of the enclosure begins to disappear. The collapse is gradual rather than immediate, but at some point below the tuning of the port, the speaker behaves as if it were operating without an enclosure and suffers from potentially damaging over-excursion. (This is why it is a good practice to use a sub-sonic filter when running a ported enclosure or a dual-reflex bandpass. Some high-quality electronic crossovers like the AudioControl 4XS incorporate a programmable subsonic filter circuit.)

Related to the loss of enclosure damping, ported and dual-reflex bandpass designs also exhibit higher distortion levels at very low frequencies than sealed or single-reflex bandpass designs. The importance of this is questionable, however, since little program material extends to below 30Hz.

Sealed enclosures and single-reflex bandpass designs have a rather shallow low-frequency roll-off rate of around 12dB/octave, whereas ported enclosures and dual-reflex bandpasses typically exhibit 18- 24dB/octave roll-off. For this reason, sealed enclosures and single-reflex bandpass boxes can have much higher -3dB points (the frequency at which the output dips 3dB below the reference efficiency of the speaker) than ported designs while still producing very good ultra-low frequency output.

30-80Hz Behavior

This is the frequency range that is most important in that it encompasses the vast majority of low-frequency information present in music. Serious audiophiles assign much more importance to good performance in this range than in the extreme low-frequency range.

At moderate power levels all of these enclosure types exhibit pretty decent manners. The ported box and the bandpass designs produce less distortion than the sealed box, but the difference is marginal.

At higher power levels things change considerably. The dual-reflex bandpass, due to the fact that its ports control cone motion over a wider range of frequencies, produces the least distortion and exhibits the best power-handling characteristics. The ported enclosure and the single-reflex bandpass also do a very good job producing high-levels of undistorted bass output, again due to reduced cone motion in this frequency range. Bringing up the rear in this category is the sealed enclosure, which produces higher levels of distortion at high power levels. There is a common misconception that ported designs produce more distortion than sealed boxes. As you can see this is not entirely accurate; it depends on the frequency and the power level.

Transient Response

Transient response refers to the ability of the subwoofer system to reproduce quick changes (transients) in the program material accurately. This is often interpreted as "tightness" or "looseness" which is maybe a dangerous terminology since many people are more influenced by tonal characteristics when asked to qualify the "tightness" of the bass. Transient response is actually a function of accuracy in relation to time rather than frequency. In music, sounds like drum strikes and quick bass guitar pulses are good tests of a subwoofer system's transient performance. A system with good transient response will reproduce these sounds with clear, "tight" definition. A system with poor transient response tends to blur these sounds over time, due to the speaker's inability to stop and start quickly enough to react to the signal accurately.

It is generally accepted that an optimized sealed enclosure exhibits the best transient response characteristics. The control provided by the air-spring in a good sealed system contribute to generally outstanding transient behavior (at very high power levels, the increased distortion can overshadow this advantage, however.)

A ported enclosure can also achieve good transient behavior but never as good as an optimized sealed enclosure. It is possible, however, for a well-designed ported enclosure to have better transient response characteristics than sealed enclosures with higher Qtc's (above 1.0.) The specific alignment of the sealed and ported enclosures plays a huge role in determining the transient characteristics of each individual subwoofer system.

Single-Reflex bandpass designs can also have good transient characteristics if their bandwidth is fairly narrow, but again, not as good as an optimized sealed enclosure. As the bandwidth becomes wider, their transient response can degrade considerably.

Dual-Reflex designs generally exhibit inferior transient response characteristics when compared to the other designs. As with single-reflex designs, narrower bandwidths produce better transient performance than wider ones.

Efficiency

The term "efficiency" refers to the ability of a speaker system to convert electrical energy (power from the amplifier) into acoustic output. Consequently, it also serves as an indication of which system will produce the loudest possible output given the same size amplifier (assuming they can all handle the power.) For the purposes of this comparison, we are looking at efficiency in the 40-80Hz octave.

Generally speaking, the most efficient enclosures are the two narrow-bandwidth bandpass designs with the dual-reflex version having a slight edge. Next in line, the wide-bandwidth dual-reflex and the ported enclosure exhibit very good efficiency as well. The sealed enclosure and the wide-bandwidth single-reflex bandpass are the least efficient designs.

Midbass transition

For sub-bass to sound natural, the system must have good midbass capability as well. These two are interrelated because harmonic components of the sounds produced by instruments that play in the sub-bass range must be accurately reproduced in the mid-bass range for a system to sound accurate.

In car audio, we normally don't have the luxury of using very large drivers to reproduce midbass. For this reason, the ability of a subwoofer system to smoothly transition to the mid-bass region becomes very important to achieving top-notch fidelity.

The sealed and ported enclosures, because the speakers play directly into the listening environment usually produce the smoothest midbass transition. Wide bandwidth bandpass designs are a little more ragged, but still deliver good midbass reinforcement. The narrow bandwidth bandpass designs can create serious problems because their high-frequency roll-off can begin as low as 75-80 Hz and the amplitude of their response peaks is very high, which necessitates the use of larger, very capable midbass speakers in order to blend smoothly with the sub-bass.

There Is No Free Lunch

As you can see by the comparison, no enclosure design is superior in all respects. They all have advantages and disadvantages. Analyzing the characteristics of each enclosure type will help you decide which enclosure type is right for your application. An informed decision involves an analysis of the following factors: the space that you want to make available in your car for the enclosure, your performance expectations (loudness, tonal qualities, etc,) the amount of amplifier power you will be using, and of course, your budget. Top-notch car audio specialists will weigh all the factors and consider all enclosure types before recommending a subwoofer system. Many will even show you specific data to support their suggestions.

Remember that the information presented here assumes that each enclosure type has been properly designed and executed. This means that the speaker and the enclosure are carefully matched as a system. The skills of a competent designer, installer and cabinet builder are every bit as important to the end result as the design of the box or the type of woofers that you buy.

Despite the very general scope of this piece, we hope it leaves you with a better understanding of subwoofer systems. At the very least, we hope that the next time you hear someone say "whatever you do, don't port the box" or "sealed boxes don't sound good," you will ask them to thoroughly explain their position. It could be amusing.

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http://www.classicsp...?showtopic=5282

Here is the thread where I took a number of measurements of my pair of later AR2ax.

In the first post there is a curve family showing the range of curves from the midrange control (tweeter at max). This duplicates what Steve's factory curves show, that the "midrange" is really quite wide range and is enough more sensitive than the dome tweeter to really be considered the primary tweeter itself.

I prefer listening at the plum middle curve setting and at that point the dome tweeter is, on average about 8dB quieter than the mid (over the range the dome operates in). I had to listen quite carefully initially to convince myself that I could hear the dome at all (dome set to max).

Since the "mid" operates from about 1500 to 15,000 Hz I would consider this a "2 way design with dome tweeter added". This is not meant as a slight but more as a description of the general design. No attempt is made to roll off above the low treble so that each driver works over its own range only, as with the typical 3-way. The turn on point of the tweeter and natural rolloff of the mid overlap by a considerable amount and I don't remember any electrical rolloff of the mid unit. I'm sure the fiberglass on the mid flattens the response by attenuating the upper range, acting more as a shelving device.

With the significant level difference between the mid and the tweeter, it isn't clear that the dome adds much to the top Octave power response. Again, this is seen in Steve's curves where the axial differences between mid and tweeter output are pretty well duplicated in the power response curve.

Regards,

David S.

I'd be surprised if ANY of us "geezers" could actually hear TODAY the 3/4" tweeter using "typical" source material. When first introduced, I think any audible differences would be subtle. They may be audible to "young folks" with great hearing, listening to recordings with significant HF energy @ the top octave. I suppose in the "far field", audible differences would be a liitle bit more obvious because the "power response" @ the upper octave is improved by adding that addtional tweeter. Still, most program material "vintage" or "current" has so little 10 Khz energy, I believe any DRAMATIC differences would be rare.

I hypothesize If the "midrangle" level control is set at "max", AND the tweeter "blew out" (open circuited), most people wouldn't hear any changes at all. However, if the midrange is set @ the midway point and the tweeter failed, THEN audible differences would be readily apparent to all. Note that if the midrange is set "midway", this "normalizes" somewhat the inherently huge level difference between the midrange and tweeter. It would also change the ACOUSTICAL crossover frequency between all THREE drivers. I'm not sure why AR didn't just ommit the level control entirely and permanently "padded" the midrange using resistors in the crossover design.

Perhaps it was part "marketing". I can't recall EVER seeing a reviewer or user NOT set that control @ "mid". Setting it at "max" would probably make the tweeter virtually inaudible (I did this and remember the sound "muffled"). I know (base on posts of others here) that the 2ax midrange was good enough to be used "full range" in the AR4x.

However, the 4x system contains a smaller woofer in a smaller cabinet, which means that the midrange level and crossover frequencies between woofer & tweeter MUST be very different when the midrange SPL is "normalized" to the AR 2ax. It's well esablished that "octave to octave" balance is the major parameter determing subjective "quality".

If I had a pristine "vintage" AR2ax system, I would probabbly re-do the crossover from scratch. The resulting sound would probably be more like the "Teleydyne AR's", but with limited power handling (the tweeter isn't "ferrofluid cooled/damped" or very "sensitive" compared to what's attainable today). Whether it's "cost-effective" to do so is debatable, but I'm sure it can be done. If I succeeded, then it would no longer be a true "classic" or "vintage", (would it ?).

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I hypothesize If the "midrangle" level control is set at "max", AND the tweeter "blew out" (open circuited), most people wouldn't hear any changes at all. .

I found that to be the case with a somewhat dated 2ax with a single, phenolic ''midrange'' and stock tweeter here: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6705&hl=ar2ax&fromsearch=1

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I'd be surprised if ANY of us "geezers" could actually hear TODAY the 3/4" tweeter using "typical" source material. When first introduced, I think any audible differences would be subtle.

The difference was subtle when the speakers were new and us "geezers" were all still young. You really don't hear much difference in the direct sound at all, but rather just "feel" an increased sense of "something" coming from the sides and above and sometimes from below that people tend to describe as "airiness."

I can still feel this change with the HF level setting, so I think my listening space must reinforce the effect. But when I walk right up to the speaker, I've never been able to hear much without putting my ear right up close to the dome, and haven't been ever since I first bought them new when I was in my early 20's.

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Actually I run them both (mid and tweet) at max, full-tilt boogie and I enjoy them there - since this is a "retro" system for myself I use the tone controls on my Marantz 2252 to adjust appropriately. There are many people who rebuild the 2-ax and remove the resistors entirely - just block the holes and run the mid-tweet "straight". Evidently at the max end of the resistor travel there is no resistance in the circuit anyway.

I do agree that I have to be close to the tweet to hear it - to verify it is working I touch it and see if I can feel any vibration ;-))). Mine are working just fine. I guess ;-))). At least they are vibrating at what feels like a high frequency.

One thing I have noticed since putting the 2-ax into play is that I think I can hear (for the first time) what all the commotion about first order crossovers is about - there may actually be something to this topology - I seem to get a more coherent and smoother sound from the 2-ax with more lower level detail than I do with speakers that feature higher-order crossovers. Final analysis on this will have to wait until I can get my CD player and vinyl engine hooked up - right now all I listen to is FM from the receiver.

Those folks at AR were really excellent engineers and builders - it is pretty amazing the quality of sound I am getting from these almost 40 year old speakers. There is almost nothing at the Big Box that can touch what I am hearing right now.

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The difference was subtle when the speakers were new and us "geezers" were all still young. You really don't hear much difference in the direct sound at all, but rather just "feel" an increased sense of "something" coming from the sides and above and sometimes from below that people tend to describe as "airiness."

I can still feel this change with the HF level setting, so I think my listening space must reinforce the effect. But when I walk right up to the speaker, I've never been able to hear much without putting my ear right up close to the dome, and haven't been ever since I first bought them new when I was in my early 20's.

I agree, Gene...Having experimented with many modern tweeters (and associated crossovers) as possible replacements, duplicating what you describe is no simple task.

AR's "white dot"/"normal" setting for the 2ax midrange pot was approximately 1/3 off the maximium setting. The tweeter setting was just a hair off maximum. It is often erroneously assumed that the white dot is the level control's halfway mark. The pots are also often improperly re-installed during restorations due to this assumption.

Mach3, When the pot is at maximum there is still 15 to16 ohms in parallel with the drivers. Completely removing the pots will change the crossover frequencies as well as the character of the speaker. It will no longer be a 2ax.

Roy

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I agree, Gene...Having experimented with many modern tweeters (and associated crossovers) as possible replacements, duplicating what you describe is no simple task.

I think this might do it, but I have yet to hear an actual setup:

http://www.dts.com/professionals/sound-technologies/audio-processing/dts-3d-audio.aspx

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Two more tangential musings ....

Looking back at the thread that Carl referenced in post #45 about the AR-2a to 2ax 'upgrade' conversion, it occurred to me that the mid-range driver in the replacement baffle board looked very familiar - - - it appears to be identical to the HF driver used in a Rectilinear XI (see pic attached). I've never seen that driver in an AR product and cannot identify the manufacturer myself, but another Rect XI owner made this statement on another audio forum:

"The tweeter is a phenolic ring tweeter. I've heard that the phenolic ring tweeters were made by CTS too, but I think I did see one from an XI that had the manufacturer code 24 (Becker) stamped on it instead. The phenolic ring tweeter has a ring (made of phenol or phenolic) that does not move, and a tweeter inside the ring."

In Mach3's post #47, he states his preference for full-tilt boogie pot settings on the speaker controls and mentions driving them with a Marantz receiver. My recollection is that most of this vintage of Marantz products have three separate pre-amp tone controls (bass-mid-treb) and I got to wondering (musing) about how much correlation there might be between the frequencies affected by the three amplifier tone controls and the frequencies delivered by the three individual drivers in the 2ax. Or more specifically, I guess, does Mach3's particular set-up, with a separate amplifier mid control, offer a wider selection of enhancement options to optimize the performance of whichever mid driver is present in this (or any other) three-way speaker?

post-112624-0-23134800-1340999298_thumb.

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