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During the past decade I've noticed the near-disappearance of this early-60s "revolutionary" design by Henry Kloss (and Edgar Vilchur?).
Why?I realize it is not as efficient as a bass-reflex design, but to me anyway, for most music it sounded awesome. Done right it usually went deeper, frequency-wise, than a similarly or larger sized ported design & was more accurate (done wrong it sounded constricted, too "flat" sounding and sucked amp power needlessly!).
Back in the early 80s, I remember speakers from Advent (5000 series w/10" woofer & 1" parabolic dome tweeter, & the Maestro, their first 3-way), Boston's series of almost flat speakers (the "A" series maybe? with 10" woofers); B&W's 801 monitor; and of course, Acoustic Research's huge 4-way model with two(!) side-mounted 12" woofers. All were sealed designs, and always suprised me with their rumbling-but-clean bass capabilities. (During college, I had a pair of Advent "Baby's"--had that infamous midrange hump, but those sealed 6.5" woofers were still able to get me written up several times!)
Is this kind of bass out of fashion, replaced by fast-n-hard bass that gets one's attention in the showroom?
Back in the mid 90's when I worked for a certain highly regarded :) mid-fi chain store (based in Eden Prairie, Minnesota.......) we sold CambridgeSoundworks' 12" acoustic suspension subwoofer with 140 watt amplifier. Yikes, that thing was scary! During Terminator 2 or The Abyss it's bass would literally shake your pants leg and was so low you felt it in your gut. Even the in-your-face Cerwin-Vega was no match. Now most subs seem to hit you over the head with hard bass but little else. And during Pink Floyd's heart beat sequence on Dark Side of the Moon it was incredible. Not overbearing, just palpable, rich tones.
I know efficiency is a major engineering goal, but powerful amps are a dime a dozen these days, so what gives?
Follow Ups:
I'm not sure acoustic suspension has really "disappeared" so much as been "transmogrified". Subwoofers that are descibed as "sealed enclosre" are essentially a specialized variant on the priciple. I'm thinking of Sunfire and M&K as examples. If I've right in supposition, acoustic suspension lives on in a number of sat/sub products.This is not so crazy if you consider one of the aspects of the was that the bass roll off was a result of increasing inefficiency rather than the an inherent inability to produce bass below a given point. Alison took advantage of this by selling an equalizer with his speakers that had a boost curve inverse to the speaker's roll off curve. The air trapped inside the sealed box protected the cones from damage but the need to compress it required a lot of power. (This was beyond my budget then, but my idea of heaven was a place where everybody got a pair of Alison One's and a Phase Linear 700!)
The same principle was capitalized on by NAD. They sold some receivers and amps with a bass extension circiut that was intended to be approximately the inverse of the roll off curve of a typical small acoustic suspension speaker. It was definatelt NOT the equivalent of the "Bass Boost" button one sees around today. In a small room it worked suprisingly well for me with a pair of Smaller Advents.
Are you still a Minnesota guy? I see from your post that you worked in Eden Praire. I live in Plymouth.
Cut-Throat
Hi,I too, prefer the sound of a sealed box (yes, I have one of those monster towers from the early/mid eighties and they still sound incredible to me).
In KEF's brochure, they show the RDM Reference line of speakers. They offer the exact same drivers in a ported design as well as a sealed design. They actually mention that the sealed one is the better one, if accuracy is the parameter. I wish I could recall the exact quote.
Regards,
Adnan
For a given dollar expenditure, a reflex system gives you subjectively better bass extension. And that sells more speakers than accuracy does.But many designers who strive for accuracy use reflex systems. They simply use alignments that maximize transient response rather than extension. Other things being equal, a low-Q sealed system will have better transient response but a higher -3 dB point than say a QB3 bass alignment. It's all tradeoffs, and we've all heard good and bad examples of both sealed and vented systems.
Among the accuracy crowd, it seems to me there's been a resurgence in transmission line speakers - Meadowlark, PMC, InnerSound, Shahinian, and a little-known but superb line called Buggtussel come to mind. I used to build speakers, and to my ears the transmission line had significant advantages over both ported and sealed enclosures. But it was much harder to get right.
When the manufacturers realized that you could get more bang for the buck with ported designs, they abandoned acoustic suspension loading. Part of this resulted from changing musical tastes. Pop music requires 50 Hz “thump” and not much below that. Not coincidentally, that’s what ported speakers do best. Speaker designers love to engineer high Q port resonances into tiny speakers to give them the requisite “thump,” the illusion that they do bass. They don’t do deep or clean bass at all, but the 50 Hz honk sells speakers. Once the manufacturers realized that they could get away with cheaper/lighter enclosures and cheaper/smaller woofers, they quickly dumped acoustic suspension designs from their speaker lines. Sealed designs are now exceedingly rare, but if you do find one, you know that the design was chosen for it’s musical prowess. This is an easy way to separate the wheat from the chaff.
Ever heard of Dunlavy? All his speakers are not ported. The bass is world class in tightness. I have their Millenniums which are +/-1 dB from 20Hz to 20KHz. The speakers are huge 300 lb 76 inch monsters that have an hourglass shape (like my wife). The tweeters are in the center so they only see a small faceplate while the speakers widen on the top and bottom to provide plenty of breathing space for the two 10 inch drivers.
When Edgar Villchur invented the sealed box acoustic suspension speaker most ported speaker systems (then known as "bass reflex" enclosures) were somewhat hit-or-miss in performance. You bought your driver, you built a big box, and then you jiggled port size and stuffing until the bass sounded least boomy and most extended. If it didn't work, try a different driver and/or build a different box.In contrast, Villchur's cabinet had to be small to work, was easily made to be optimally damped, and (neglecting room loading effects) nicely flat down to the cutoff point
What changed that was the publication of Thiel's and Small's methodology for accurately matching enclosure and driver parameters to give the response desired. Using T-S, ported systems could be designed on paper to yield predictable low-frequency extension, damping, and efficiency. Best of all, for a given combination of the above, a T-S ported system will be physically more compact than the equivalent sealed box system.
The acoustic suspension speaker was more predictably accurate in its day, and its compact size was just in time for stereo. But T-S and digital computer modeling makes ported system design equally predictable now.
The acoustic suspension speaker was more predictably accurate in its day, and its compact size was just in time for stereo. But T-S and digital computer modeling makes ported system design equally predictable now.
*****************************************************************Computer modeling along with the work of T&S has made ported systems more predictable but they will always be transiently inferiour to sealed box systems. Its just the nature of the beast.
Sparky
To get the same extention the enclosure size needs to be, well the size of the 70's golden rule rectangle box. IE big. People don't like big in their houses that much. Driver manufacturers are giving what the designers want, designers are giving what the consumer wants, the consumer wants a button sized speaker that "shakes the house dude".Even in the monsters of high end, to go sealed they have to get even more monsterous in size. Buyers then throw the "must have a narrow baffle to image" back at the dealer/designers.
BTW a reflex speaker can be made to have the same even better rize/fall times (Q in sealed terms) as a sealed system. Many don't, but some do.
BTW a reflex speaker can be made to have the same even better rize/fall times (Q in sealed terms) as a sealed system. Many don't, but some do.
**************************************************************This is only true down to the port tuning freq. At that point a vented system rapidly looses woofer control below Fb. Everyone seems to only look at F3 for comparision but to get a better comparision one should a little further at F10. When you look at F10 both systems tend to be much closer in freq due to the sealed box systems shallower roll off rate (-12db/octave sealed -18db/octave vented). Now the sealed box woofer will have better control of the woofer and the transients involved with bass. This seems to be most important with speakers that get down beyond 35hz-40hz and lower. After all speaker response is still useful below F3.
Sparky
Your exact comments are why I'm still using and loving the sound from my Dalhquist DQ-10 (circa 1974!).I know that most people here are sick of me talking about them, but you have summed up everything that I feel is right about this so-called 'outdated' design. So what if it doesn't measure anywhere near neutral and supposedly takes a ton of power to drive?! IT STILL SOUNDS MUSICAL (yes, I meant to shout that!)
Just admiring your 'guts' for voicing your opinion about acoustic suspension! I'm sure the flamers are just waiting to slam these opinions, both yours and mine (sarcasm- that last line! hehehe).
Cheers and warm regards!
Dman
Yes it is found at regnar.com called RG-10 about $4,000
IMO, I simply believe that the manufacturers want to have the widest measured flat bandwidth possible so that their sales brochures seem more impressive. I believe that sealed enclosures with a Qtc of .8-.7 sound superior to even the best ported design but even I find myself favoring ported enclosures from time to time simply because of the extended low bass that sounds better with some music. Example: Tori Amos sounds great on sealed especially because of the bass guitar and drums in her music but Bjork sounds alot better with ported LF because of the extreme low frequency content and electronic music theme.
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