The midwoofer-tweeter-midwoofer loudspeaker configuration (called MTM, for short) was created by Joseph D'Appolito as a way of correcting the inherent lobe tilting of a typical mid-tweeter (MT) configuration, at the crossover frequency, unless time-aligned.
In past decades, ESS of California produced a series of hybrid loudspeakers using such tweeters, along with conventional woofers, referring to them as Heil transducers after their inventor, Oskar Heil.
In the original D'Appolito MTM arrangement, a symmetrical arrangement of drivers is used to create a symmetrical off-axis response when using third-order crossovers.
On the Saturday, August 21 occurrence, the conspicuous objects were in full view of gridlocked traffic making egress from Tinley Park's 28,000 seat First Midwest Bank Amphitheater (at that time called Tweeter Center) where Ozzfest had just ended, creating another aggregation of observers.
In the late 1970s and early 1980s, a sound recording engineer named Bob Clearmountain was said to have hung tissue paper over the tweeter of his pair of Yamaha NS-10 speakers to tame the over-bright treble coming from it.
First Midwest Bank Amphitheatre (formerly Tweeter Center Chicago), located in Tinley Park, Illinois, near Chicago, Illinois
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Susquehanna Bank Center (formerly Tweeter Center at the Waterfront), located in Camden, New Jersey, near Philadelphia, Pennsylvania
The album featured the duo's biggest-selling hit, a funk rock styled cover of "Proud Mary" and also featured another popular Ike & Tina song, the Ike Turner & Alliene Bullock-composed "Funkier Than a Mosquita's Tweeter", later covered by Nina Simone.