Well now, that is a good, if rudimentary blending of the theoretical, practical, and psychological aspects of sound-in-my-room. In the guise of super-geeky language, you are actually talking very practical matters.
You seem to be using the term "nothing wrong" to precede what turns out to be a fundamental criticism of T-S.
Yes the math is honky-dory - nobody questions the model or has a better one to offer about the motions of the air molecules, as far as I know; but the audible results aren't always so great.
You've mentioned some. I had in mind whether a "boom box" sound with three resonances and all kinds of supporting and destructing air flows from different holes gives as nice a sound as, for example, a sealed box with one resonance and a mild roll-off below and inherently possessing negative feedback and cone motion control. Considerations of that sort, like those you mention posed in more formal language, are part of the fundamental criticism of T-S.
You seem to be using the term "nothing wrong" to precede what turns out to be a fundamental criticism of T-S.
Yes the math is honky-dory - nobody questions the model or has a better one to offer about the motions of the air molecules, as far as I know; but the audible results aren't always so great.
You've mentioned some. I had in mind whether a "boom box" sound with three resonances and all kinds of supporting and destructing air flows from different holes gives as nice a sound as, for example, a sealed box with one resonance and a mild roll-off below and inherently possessing negative feedback and cone motion control. Considerations of that sort, like those you mention posed in more formal language, are part of the fundamental criticism of T-S.
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The AR-2? has a DCR of 5.5 ohms, if it reaches that low of an impedance in box the power delivered at 15 V is about 41 watts.
Of course it's rudimentary. I didn't want to take a dozen pages and tons of diagrams, along with a detour into neurology, to make the case. And the language isn't that super-geeky; it's as simple as possible without waving equations at people, yet giving DIYers a base to start playing with their own systems.
In any event, I think we're not far apart here. The math is sound, but it can be used for Good (yay!) or Evil (boooo). The alignments in Thiele's original paper were meant as guidelines for designers, but there's nothing (apart from a few editorial statements from the author about "boom-boxes") claiming these were the One True Table forever and ever, selah. He even includes a few alignments (i.e. QB3) which are not strictly according to Hoyle. Since then we've learned a few things about rooms, notably from Floyd Toole's work at NRC, so we know better than to insist on perfectly flat alignments now.
Actually, T-S shows three holes in a box sum up to one larger hole since the air masses are all on the boundary between the cabinet volume compliance and the outer world. Resonances for each individual hole do not exist at low frequencies. (quarter-wave resonances from port lengths, which T-S does not cover, are something else entirely)
There is no fundamental criticism of T-S to be made: the theory works, it gives repeatable values, and one can move backwards from existing systems to generate their responses. How people use it, however, is a matter open for discussion, and there we are in violent agreement.
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T-S kind of analysis may give very accurate predictions of what's coming out of the box*. But there's a gap between that and what is good sound in practice. And just to clarify my earlier example, whether the three-hump output of ported speakers makes for nice sound or intolerable boom (as I and many others attest to).
You seem to miss the obvious point that T-S model isn't helpful about sound in rooms from those boxes (which can be in corners or mid-wall, etc.) or a lot of important aspects external to the theory which you seem to hide under the phrase "how people use it."
I await with barely controllable anticipation your pronouncements on neurology and how that relates to T-S driver parameters.
*At least for a steady-state or model-friendly sounds and tractable driver behaviour... unknown in music, of course. But why kick a great model for stuff it doesn't try to do.
You seem to miss the obvious point that T-S model isn't helpful about sound in rooms from those boxes (which can be in corners or mid-wall, etc.) or a lot of important aspects external to the theory which you seem to hide under the phrase "how people use it."
I await with barely controllable anticipation your pronouncements on neurology and how that relates to T-S driver parameters.
*At least for a steady-state or model-friendly sounds and tractable driver behaviour... unknown in music, of course. But why kick a great model for stuff it doesn't try to do.
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I refuse to discuss matters any further with someone exhibiting your lack of manners. Good day, sir.
My ancient AR-1 has with my DVM a DC resistance of 3.2 ohms, test leads, voice coil, and who knows what.
Unfortunately, my AR-2? speakers now have a VCR of infinite impedance.
I retested the Totem sub distortion with the AR-2? speaker, distortion above 20 Hz was similar to the sealed cabinet, just with a higher SPL level.
Did some sub only (100 Hz BW24 crossover) A/B listening, the Totem was the clear winner for deep bass music, the sealed AR-2? sounded better when the fundamentals were up in the 100 Hz range where the Totem sub has a null.
After listening to music, I added the second AR cone to the sub in a push pull arrangement. I had not tried the Totem sub with my other shop sub to see how it integrated, since I knew I needed the extra level the second cone would provide, and was hoping that it might have reduced the 100 Hz null.
I then went to do a 60 Hz sine wave test, but forgot I had turned the amp wide open, which delivered 64 V (about 1000 watts), resulting in a loud "clack" and two open voice coils. The AR drivers lasted less time than it takes to read the word "clack", oops 🙁.
Was really curious if the distortion would have reduced with the push pull arrangement.
Maybe I'll find another pair of acoustic suspension speakers by the road again and re-test...
Art Welter
All of the information and advice you could want about AR speakers is available at;
Home Page | The Classic Speaker Pages
There is a great deal of experience and advice about restoring old AR, KLH, Advent, and other New England speakers but the main focus is on AR.
AR-1 and its derivatives -1W, 3, 3a, 10, 10pi etc. use the same 12" acoustic suspension driver. The driver, enclosure, and stuffing form a low frequency system that has been optimized. These components work together to produce bass flat with an f3 of 42 hz, Q of .707, a 12 db per octave slope below F3, and THD of 5% at very low frequencies. The driver is rated at 150-200 watts RMS and has been tested to handle peak impulse power of over 1 KW. It is relatively ineffecient probably around 83db 1w/1m, has a nominal impedance of 4 ohms but is probably close to 1 ohm or less at some frequencies. This makes it a very difficult speaker to drive unless you have a high quality amplifier. It will shut down or blow up typical HT receivers.
The speaker is equalizable to the lowest limits of audibility and was the scientific and musical reference standard for many pros for a long time. AR3is in the Smithsonian. AR3a was also a reference standard.
The best advice is to restore this speaker system as closely as possible to its original state. You can use it as a woofer in a 3 way system or as a sub woofer. I would not attempt to use it in any kind of enclosure except a sealed enclosure exactly as it was originally designed. There are complete specs at the web site's library. I would also not drive it when it is not mounted in its sealed enclosure. Lack of air resistance to provide a restoring force to an AS driver can badly damage the voice coil if it is operated that way.
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