no, but it's about SQ, and what the OP was asking about. Your comment that it's due to sealed speakers being harder to drive is mistaken.
you've got your history a bit mixed up, sealed designs have been around longer than my 64yrs on this planet.
Acoustic suspension or air suspension is a variation of the closed-box enclosure, using a box size that exploits the almost linear air spring resulting in a −3 dB low-frequency cut-off point of 30–40 Hz from a box of only one to two cubic feet or so.
[17] The "spring" suspension that restores the cone to a neutral position is a combination of an exceptionally compliant (soft) woofer suspension, and the air inside the enclosure. At frequencies below system resonance, the air pressure caused by the cone motion is the dominant force. Developed by
Edgar Villchur in
1954, this technique was used in the very successful
Acoustic Research line of "bookshelf" speakers in the 1960s–70s. The acoustic suspension principle takes advantage of this relatively linear spring. The enhanced suspension linearity of this type of system is an advantage. For a specific driver, an optimal acoustic suspension cabinet will be smaller than a bass reflex, but the bass reflex cabinet will have a lower −3 dB point. The voltage sensitivity above the tuning frequency remains a function of the driver, and not of the cabinet design
Ported (or reflex) enclosures
Bass reflex enclosure.
RCA
shelf stereo bass reflex multi-way speakers.
Also known as vented (or ported) systems, these enclosures have a vent or hole cut into the cabinet and a port tube affixed to the hole, to improve low-frequency output, increase efficiency, or reduce the size of an enclosure. Bass reflex designs are used in home stereo speakers (including both low- to mid-priced speaker cabinets and expensive
hi-fi cabinets),
bass amplifier speaker cabinets,
keyboard amplifier cabinets,
subwoofer cabinets and
PA system speaker cabinets. Vented or ported cabinets use
cabinet openings or transform and transmit low-frequency energy from the rear of the speaker to the listener. They deliberately and successfully exploit
Helmholtz resonance. As with sealed enclosures, they may be empty, lined, filled or (rarely) stuffed with damping materials. Port tuning frequency is a function of the cross-sectional area of the port and its length. This enclosure type is very common, and provides more sound pressure level near the tuning frequency than a sealed enclosure of the same volume, although it actually has less low frequency output at frequencies well below the cut-off frequency, since the "rolloff" is steeper (24 dB/octave versus 12 dB/octave for a sealed enclosure).
Malcolm Hill pioneered the use of these designs in a live event context in the early
1970s.
[18]
Vented system design using computer modeling has been practiced since about
1985. It made extensive use of the theory developed by researchers such as Thiele,
[19][20][21] Benson,
[22][23] Small
[24][25][26][27] and Keele,
[28] who had systematically applied electrical filter theory to the acoustic behavior of loudspeakers in enclosures. In particular
Thiele and Small became very well known for their work. While ported loudspeakers had been produced for many years before computer modeling, achieving optimum performance was challenging, as it is a complex sum of the properties of the specific driver, the enclosure and port, because of imperfect understanding of the assorted interactions. These enclosures are sensitive to small variations in driver characteristics and require special quality control concern for uniform performance across a production run. Bass ports are widely used in
subwoofers for
PA systems and
sound reinforcement systems, in
bass amp speaker cabinets and in
keyboard amp speaker cabinets
(1 review)
.png)
