* too inefficient vs. bass-reflex, its main competitor?
* people became irritated at paying extra for more powerful amps that could drive acoustic-suspension speakers to their full potential?
* generally speaking, more people preferred the sound of a bass-reflex design i.e. bass reflex is generally "punchier", more "lively" etc?
Through the 60s and 70s acoustic-suspension loudspeakers seemed to be everywhere. But by the early 80s only Infinity, KEF, Advent, Celestion, Boston Acoustics and a handful of others here in the States still sold them. Then by the mid 90s, I believe only Advent and Cambridge SoundWorks (founded by Henry Kloss......who founded Advent!) still sold them and now as far as I can see, at least as far as the mid-fi class is concerned*, no one sells them.
Just curious, as I like the sound of the acoustic-suspension system, though I know that on paper supposedly a bass reflex should sound the same.....but to me they don't.
* I know that term will bother someone but I don't know what else to call the Advent/Infinity/etc price point
* people became irritated at paying extra for more powerful amps that could drive acoustic-suspension speakers to their full potential?
* generally speaking, more people preferred the sound of a bass-reflex design i.e. bass reflex is generally "punchier", more "lively" etc?
Through the 60s and 70s acoustic-suspension loudspeakers seemed to be everywhere. But by the early 80s only Infinity, KEF, Advent, Celestion, Boston Acoustics and a handful of others here in the States still sold them. Then by the mid 90s, I believe only Advent and Cambridge SoundWorks (founded by Henry Kloss......who founded Advent!) still sold them and now as far as I can see, at least as far as the mid-fi class is concerned*, no one sells them.
Just curious, as I like the sound of the acoustic-suspension system, though I know that on paper supposedly a bass reflex should sound the same.....but to me they don't.
* I know that term will bother someone but I don't know what else to call the Advent/Infinity/etc price point
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Interesting post. I had never thought of it as an issue before. Maybe one factor was the publication of Neville Thiele's work by the JAES in about 1970. (Btw that paper was first published in Australia ten years earlier and went "under the radar" for a decade.) Those papers may have allowed people to build reflex enclosures with much more confidence as it now had an established technical basis.
Another reason may be that we, the fickle public, prefer ports etc as they look more sophisticated...! Like you I quite like the classic acoustic suspension. Colloms ("High performance Loudspeakers" 1978) has results that suggest that although the 4th order reflex can have "more" bass than a 2nd order closed box people can prefer the slower roll off. Less phase change is one possible explanation.
Also the "less efficient" tag that closed boxes have had to wear is not as straightforward
as it first appears. I have read most of the T/S papers and I recall that they make the point that all things being equal the mid-range efficiency is identical for identical drivers.
Another reason may be that we, the fickle public, prefer ports etc as they look more sophisticated...! Like you I quite like the classic acoustic suspension. Colloms ("High performance Loudspeakers" 1978) has results that suggest that although the 4th order reflex can have "more" bass than a 2nd order closed box people can prefer the slower roll off. Less phase change is one possible explanation.
Also the "less efficient" tag that closed boxes have had to wear is not as straightforward
as it first appears. I have read most of the T/S papers and I recall that they make the point that all things being equal the mid-range efficiency is identical for identical drivers.
What killed Acoustic Suspension?
The Thiele and then the Small papers and all the simulation programs made design of proper vented box designs much simpler. The advantages where better power handling near cuttoff and greater bass extension. The real disadvantage is that either a larger box (for a given woofer) or more magnet (for the same box volume) would both lead to more cost than an acoustic suspension counterpart.
Higher order leads to slightly higher transient ringing. I'll let the opponents prove that they can hear the difference.
David S.
The Thiele and then the Small papers and all the simulation programs made design of proper vented box designs much simpler. The advantages where better power handling near cuttoff and greater bass extension. The real disadvantage is that either a larger box (for a given woofer) or more magnet (for the same box volume) would both lead to more cost than an acoustic suspension counterpart.
Higher order leads to slightly higher transient ringing. I'll let the opponents prove that they can hear the difference.
David S.
I think the OP did a pretty good job of answering his question in his first post. I'm also of the belief that most commercial consumer-oriented speaker systems sold today are vented because they are less expensive to produce because they require less precise woofer specs and have lower bass extension - all else being =.
To each their own but I completely disagree with this.
I like the traditional acoustic suspension system too, nothing more than a smallish sealed box with a suitable driver to get down lower in frequency than most do. IMO, the problem today is finding a suitable driver. I know of no source for drivers that loosely suspended, with that low an Fs. If you're going to do a sealed box with a large driver it usually ends up larger than people want. Tuned ports or passive radiators get you the more reasonably sized boxes without sacrificing low frequency performance. BTW, I do believe if you're going to use a subwoofer, a sealed box for the higher frequencies solves a lot of phase problems.
I built my speakers as sealed/acoustic suspension, and certainly don't regret it.
My primary reason for doing so was their use in a smaller room where I thought that the shallow but earlier roll-off characteristic would, with room gain factored in, produce a more neutral and extended response. This seems to be the case and the bass is remarkably extended (these are Hi-Vi M8a drivers in 28L, -3db at 57Hz, -10dB at 31Hz), not much is missing in practise and the sound is very tight.
Another factor putting me off ported was having to contend with possible midrange leakage from the port and the general limitation on how much stuffing material could be used, as too much would choke the port.
Myself, I'd go with sealed again in the future, a slightly large well stuffed cabinet.
My primary reason for doing so was their use in a smaller room where I thought that the shallow but earlier roll-off characteristic would, with room gain factored in, produce a more neutral and extended response. This seems to be the case and the bass is remarkably extended (these are Hi-Vi M8a drivers in 28L, -3db at 57Hz, -10dB at 31Hz), not much is missing in practise and the sound is very tight.
Another factor putting me off ported was having to contend with possible midrange leakage from the port and the general limitation on how much stuffing material could be used, as too much would choke the port.
Myself, I'd go with sealed again in the future, a slightly large well stuffed cabinet.
ABTechservices.com (http://www.abtechservices.com/) sells S.E. Asian produced woofers as replacements for the classic acoustic suspension brands like AR, Advent & Jensen. The proprietors of the business (supposedly former AR employees) claim they are produced to original driver specs.
So, if you want to spend the $, they offer the 11 inch AR3a style woofer that was designed to work in a 1.6 cu.ft. box. Fs should be in the 15-20 hz range. Box target Fc is about 42 hz.
>>> What killed Acoustic Suspension?
>>> The Thiele and then the Small papers and all the simulation programs made design of proper vented box designs much simpler.
Bill, what components are used in your speakers in the pic? They look terrific!
When i first read this post i thought sealed is not dead and never will be dead. But yes, Thiele/Small made it easier to design ported boxes that also sound very good.
Personally, i prefer back horns and open baffle... measurements be damned! I'm in this hobby for the SOUND!
>>> The Thiele and then the Small papers and all the simulation programs made design of proper vented box designs much simpler.
Bill, what components are used in your speakers in the pic? They look terrific!
When i first read this post i thought sealed is not dead and never will be dead. But yes, Thiele/Small made it easier to design ported boxes that also sound very good.
Personally, i prefer back horns and open baffle... measurements be damned! I'm in this hobby for the SOUND!
As was said above, the ideal is a bit floppy with a low Fs. That's a 12" Utah RXC21 which some say was made by, or influenced by Altec, perhaps because of it's "bungee cord" bass. The T-S are very much like the Altec 414: QTS is .31, VAS 8.4 and Fs 27. I tried with a port, with a vent and finally sealed which was juuuust right.
The tweet is the S-B Acoustics SB29 which slays the Vifa/SEas XT25 in tone and texture but which I can't get to image w/o extreme toeing in. Maybe I need to work the crossover for phase, like a Butterworth or LW but I'm not very well educated. I just have a 1/2 mH coil on the woof and a cap for 2800 Hz on the tweet.
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Ken Kantor has - I unfortunately do not recalll the publication- already answered part of the question, when asked why not more AS woofers were available but his own NHT's .
Very few manufacturers these days are willing or even able to produce the highly compliant woofers that are needed for a proper AS driver. Have a look at e.g. the Acoustic Research AR3/3A/9/11 12" woofer and compare the mechanical (not the electric!) specs with any of todays 12" woofer. Very low Fs, High Vas en Cms of more than 1 mm/N.
I do not know of any current 12" medium moving mass (<60 gramms) with an Fs of 16-18 Hz and a Vas of approx 300 Litres/10 cubic feet. Scan Speak used to produce such woofers, but to my best of knowledge has also gone over to the less compliant camp.
Regards,
Eelco
Very few manufacturers these days are willing or even able to produce the highly compliant woofers that are needed for a proper AS driver. Have a look at e.g. the Acoustic Research AR3/3A/9/11 12" woofer and compare the mechanical (not the electric!) specs with any of todays 12" woofer. Very low Fs, High Vas en Cms of more than 1 mm/N.
I do not know of any current 12" medium moving mass (<60 gramms) with an Fs of 16-18 Hz and a Vas of approx 300 Litres/10 cubic feet. Scan Speak used to produce such woofers, but to my best of knowledge has also gone over to the less compliant camp.
Regards,
Eelco
Did you overlook my post #14? There is a possible source. I can't vouch for ABT's AR3a woofer specs. You'll have to ask them.
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