Foam Plugs

Basically, if you got to put your speakers near the wall or corners, then you'll probably need the "foam plug" to help tame the bass "boominess". Of course, there is a part of me that ask the question "why don't they make acoustic supension speakers anymore?". Seems to me, that you didn't have near the issues with speakers placement, back when "acoustic suspension" speakers were the norm.

Rodman99999, "If the plugs are closed cell foam; the alignment becomes an acoustic suspension."

Maybe, but probably not. What you have is more or less a sealed box alignment. Acoustic Suspension is more specific than that, and requires certain parameters be met. Not that the ingredients involved in implementing bass reflex and Acoustic Suspension designs are mutually exclusive, but in my opinion, it's difficult to have both bases covered. I'm confident you know the differences based on our prior discussions, but just want to make sure there is no confusion on the part of those reading here.

I agree with your statement on the reason the plugs would be supplied. However, I remain dubious as to whether a design that was presumably optimized with a bass reflex alignment would not be facing a one step forward, three steps back situation with the plugs installed.

Then again, given that many who design loudspeakers today are more possessing in cabinetry/veneering ability than the requisite mathematics and engineering involved in loudspeaker design, the assertion I made about "presumably optimized" bass reflex alignment (some would argue there is no such thing) might be asking far more more than said folks are capable of.

Mr T- Yes, I do understand your point. However, most make no distinctions between sealed box and 2nd order/acoustic suspension designs nowdays. ie: This site moves directly from a 2nd order alignment(calling it variously, "2nd Order", "Acoustic Suspension" and "Sealed Enclosure"), to a 4th order alignment: (http://www.danmarx.org/audioinnovation/theories.html) I do agree that IF the woofer and enclosure were optimized as a 4th order alignment, it would not be optimized as a 2nd order, with the vent sealed. BUT- the woofer would still be operating with the enclosure volume acting as an air spring(acoustic suspension). Actually- Villchur came up with the "Acoustic Suspension" design around 1954, and started building speakers with Henry Kloss, somewhat before A. N. Thiele published anything concerning speaker parameters, or cabinet alignments(around 1961), so things could actually get (somewhat)"optimized."

Rodman99999, "However, most make no distinctions between sealed box and 2nd order/acoustic suspension designs nowdays." That solidifies my feeling regarding the dumbing down of the craft over the past decade-plus.

Beyond that, thank you for your explanation.

Sadly, it seems as if cabinetry occupies the lion's share of loudspeaker design today. If one ever saw his own personal loudspeakers, they would guess that Bud Fried must be turning over in his grave right now.

I take a more skeptical view of how successful a woofer designed to be used in a vented alignment would do in Acoustic Suspension duties as their responsibilities are far more different than the average Joe understands. Claw and upholstery hammers both drive nails, yet clearly serve very different functions, as do Acoustic Suspension woofers and those to be used in bass reflex cabinets. People trivialize this these days, due to a lack of understanding and familiarity. The (low - mid power) tube renaissance brought along with it the need for maximum loudspeaker efficiency, which usually means bass reflex speakers. Now, the pendulum has swung too far the other way, and folks are missing out on the advantages Acoustic Suspsension brings to the table.

Anecdotally, a friend of mine, whose loudspeaker ports (made of cork) deteriorated to a great degree over the years, and then replaced them, experimented with stuffing them. He was not at all happy with the results, and soon removed the material, never to go back. That put a real bad taste in his mouth about sealed speakers in general. To me, it was not surprising, as the Focal made woofers in his speakers were simply not designed to be used in that application.

Finally, the Acoustic Suspsension alignment is probably the greatest post war advance in high-end audio. Most agree it was the very thing that brought (en masse) stereo sound reproduction into the home. Think about it, would we all be still listening in mono otherwise? Like most implementations of genius, it was amazingly simple. As you know, Villchur had no desire to manufacture a loudspeaker, he simply wanted to sell the idea to a company in the business, and make a few bucks in the process. To put it politely but literally, he was laughed out of every room he presented his idea. I admire the spirit and determination of a man who answers this type of rejection with building one of the most successful high-end audio companies ever ala implementing his vision.

A true "acoustic suspension" speaker system involves a woofer with a free air resonance of about 15 Hz. My KLH12s were 14 Hz. You can't find a driver like that today. Evidently speaker system designers today just don't trust that trapped air creates a spring. A spring more nearly linear than any driver's compliance.

"Sealed box" they may be, but not truly acoustic suspension.