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What killed off the acoustic-suspension speaker?
What killed off the acoustic-suspension speaker?
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Old 31st August 2011, 08:00 AM   #1
River757 is offline River757  United States
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Default What killed off the acoustic-suspension speaker?

* 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

Last edited by River757; 31st August 2011 at 08:03 AM.
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Old 31st August 2011, 08:21 AM   #2
chris661 is offline chris661  United Kingdom
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Acoustic suspension could mean, to me, one of two things:

A standard sealed box
A ported box with stuffed (or v.high aspect ratio) ports, which makes them aperiodic.

I suspect you mean the first one, but could you clear that up?
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Old 31st August 2011, 08:55 AM   #3
Jonathan Bright is offline Jonathan Bright  Australia
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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.
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Old 31st August 2011, 09:16 AM   #4
toprepairman is offline toprepairman  United Kingdom
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Wouldn't touch a ported speaker at all, they completely mess up bass transients, there's no place for them in serious HiFi.
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Old 31st August 2011, 09:27 AM   #5
sofaspud is offline sofaspud  United States
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Old 31st August 2011, 09:53 AM   #6
QSerraTico_Tico is offline QSerraTico_Tico  Europe
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The rotten edge suspension!
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Old 31st August 2011, 10:06 AM   #7
CLS is offline CLS  Taiwan
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I've heard that there're some QC issues about those very soft suspensions -- hard to make them in a consistent compliance. Maybe it's labor intensive, i.e., expensive.

Not sure, maybe just a rumor...
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Old 31st August 2011, 12:22 PM   #8
speaker dave is offline speaker dave  United States
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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.
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Old 31st August 2011, 12:39 PM   #9
BillEpstein is offline BillEpstein  United States
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Old 31st August 2011, 12:51 PM   #10
speakerdoctor is offline speakerdoctor  United States
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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 =.
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