Why not acoustic suspension?


When I was young, late 60's early 70's, the sealed or acoustic suspension speakers were quite commonplace. Now bass reflex, ported speakers seem to be much more common. My understanding is that both speaker designs, assuming competent design will perform very well. Perhaps with the ported getting a slightly lower bass response and higher efficiency gives it the edge. Thinking efficiency though, amplifier watts don't cost that much more today so it doesn't seem like a deal maker. What I don't understand from a pragmatic corporate standpoint is why more acoustic suspension speakers aren't available. My understanding is that the sealed speaker box can be smaller which would be a plus from a cost standpoint, both in less material, lighter cabinet and more speakers could be shipped in a truck reducing shipping cost. Any thoughts as to why the industry has shifted so hard in the bass reflex direction?

61falcon

I just learned something new.  I guess there’s a range of suspension / box configurations.  To me it’s all AS, but I guess in the formal sense, a true AS has to have a soft, compliant suspension.  

Modern speakers often have stiffer suspensions and while the air in the box is important in terms of the suspension it’s not as dominant. 

I stand corrected, my thanks and apologies.  I learned something new! 

Among the many differences of the modern sealed approach apparently is the reduced sensitivity to the box size.   This used to be a big deal.  

It's not UNIMPORTANT, but with the dominance of the driver suspension it can't hold as much sway as before.  

So are there many acoustic suspension subwoofers?

The AR 1W must have been the granddaddy of them all.

I guess the Sunfire True Sub was not technically acoustic suspension because it used a passive radiator?

@61falcon 

"Can anyone name modern acoustic suspension, true acoustic suspension speakers made today?"

The ATC SCM7 - SCM20 series are acoustic suspension which refers to any speaker whose woofer is mounted in a sealed encloser where the air trapped inside acts like a spring stabilizes the loose and floppy cone suspension. Acoustic suspension is also known as an infinite baffle.

The advantages lower frequency extension, a more benign or smoother impedance modulus and lower bass distortion. The disadvantages are mostly dramatically less efficiency requiring a more powerful amplifier. 

It was common to see rather large enclosures at one time with woofers of twelve to fifteen inches or more that could reproduce bass notes as low as 15Hz. Some of these were produced by ADS, Avid, Cerwin Vega and others. The Advent Loudspeaker, the Acoustic Research AR 3a though smaller than the above were still fairly large with up to two square feet of internal encloser volume. Radio Shack also marketed quite a few fairly large acoustic suspension speaker systems.

BTW, I asked fellow hobbyists at DIYaudio, and the consensus is that we still call a box with a driver in a sealed box of small size "acoustic suspension." 

The drivers have changed over time but a sealed box is almost always acoustic suspension.  Disagreements should come over to DIYaudio. :) 

So if the box includes a passive radiator, it is technically not "sealed"?  Which would make my Thiel 3.6s and Sunfire subs not acoustic suspension?