Amazing discovery.
i have no idea at all what my phase tech pc8.5 really features other than it has the first softdome tweeter. Now i know, its enclosure design was actually based on a historical invention in audio technology in the 1950s. All the while i thought that there was really a vacuum speaker. Sounds funny but irwin had far more advanced comprehension and appreciation of what hi-end music then, than me.
He actually had an Acoustic Research set of speakers. he referred to it as a sealed box.
Googled the AR and lo and behold, sealed box is an acoustic air suspension system for a speaker application. Acoustic Suspension was invented by Acoustic Research, USA, in the 1950s.
The AR3AQuotes:- AR-3 (and before it, the AR-1) has been regarded as the granddaddy of acoustic or air suspension speaker system. Source:
AR3A- AR-3 was placed on permanent display in the Information Age Exhibit of The National Museum of American History at The Smithsonian Institution in Washington, DC. Source:
AR3a Museum Many reputable audio companies applied the same technology in their hi-end speakers. KEF, Rogers, and Spendor called or termed it either as infinite, sealed or closed baffles. In large format, B&W, MK, Celestion, AR, Dalquist, Phasetech, McIntosh, Mastercraft, Hales Audio, Monitor Audio, Infinity Kappa, etc. also followed the technology. They were also expensive.
Sealed Box Speakers:
KEF Reference Series 101 BBC LS3/5ARogers,
SpendorBut acoustic suspension is rarely manufactured or used in new and current models after AR was bought out by another company. Dont know who acquired the license on the technology.
My restored 1st Phase Tech PC 8.5 (Sealed Box with 3 Drivers) My newly restored 2nd set, baptized as MacPhase LS8.5 (Sealed Box with 4 Drivers)