Speaker design myths revealed

golix@macunlimited.net...The term "sealed box" means that the box is relatively small and air tight so that air compressed within the box contributes much of the spring effect on the driver cone. Because of the air spring (which is very linear) the mechanical cone suspension of the driver must be very soft and floppy.

Infinite baffle is also a sealed box, but it is so large, and imperfectly sealed, that there is essentially no spring provided by air pressure. Accordingly the mechanical cone suspension must be designed to do the job without any help. A typical IB installation would be a large LF driver mounted in a door leading to the attic.
Parts Express sells some drivers that are designed for IB use.

Think of an Infinite Baffle ( IB ) design as a dipole radiator ( Maggie's, E-stat's, etc... ) but the rear radiation never comes in contact with the front wave. The result is no cancellation or reinforcement. The driver is basically "unloaded" due to having no "pressure" on it from a small cabinet.

This is completely different from an "acoustic suspension" design, which maintains constant pressure on the woofer. In an "acoustic suspension" design, the electro-acoustic characteristics of the box volume contribute to the suspension ( compliance ) of the driver. In effect, a "sealed box" is typically a generic term for an "acoustic suspension" design, but not always. As such, an IB does NOT have to be in a sealed box and a sealed box is not always an acoustic suspension design. It can be quite confusing even though the end results are somewhat similar in performance when all is said and done.

What constitutes an IB design is that the front wave and back wave are completely isolated OR isolated well enough that the length of the path where the two waves do meet is below the usable bandwidth of the driver itself. This means a HUGE baffle area ( a wall ) if mounting it in an "open box" design. Some people with basements will mount the woofers in the floor, utilizing the entire basement as the "cabinet" for the back wave of the driver.

In effect, "infinite baffle" simply means that the front wave is "separated" from the back wave due to the use of a "baffle" of "infinite" size. That baffle can be either phenomenally tall and wide OR it can be very deep and "acoustically absorbing". Both end up making for a long signal path that encourages isolation between the front and back waves of a driver.

Some "sealed" designs are consided to be IB's when the internal box volume is much larger than the driver's electrical operating characteristics as mounted in free space. That's because the volume of the sealed box is so great that there isn't enough "pressure" generated within it when the woofer moves to alter the tuning of the driver itself. In effect, the back wave is simply "lost" within the volume of the absolutely huge sealed and stuffed box. Sean
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PS... Many drivers that are designed for use in a "free air" system work well in an Infinite Baffle design. As a general rule, IB's do not have quite as tight of bass or as good of transient response as a properly designed low Q "acoustic suspension" design, but they can be very, very good none the less.

I just found this when Googling for some other stuff. Not exactly an in-depth explanation of each design, but the basics are covered. Sean
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Simple explanations of various loudspeaker cabinet designs.

PS... I don't know what their affiliation was, but i think that Xtant was somehow affiliated with McIntosh i.e. possibly their car stereo division at one point in time prior to Clarion purchasing Mac. I could be wrong about this though....