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The speaker sees the text on the screen reflected in the mirror, while the audience sees what looks like a sheet of tinted glass on each side of the speaker. Schlafly's glass teleprompters were also used for the 1956 Republican National Convention , and at both parties' conventions from then on.
The midwoofer-tweeter-midwoofer loudspeaker configuration (called MTM, for short) was a design arrangement from the late 1960s that suffered from serious lobing issues that prevented its popularity until it was perfected 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. [1]
A one sheet is a specific size (typically 27 by 41 inches (69 cm × 104 cm) before 1985; 27 by 40 inches (69 cm × 102 cm) after 1985) of film poster advertising. Multiple one-sheets are used to assemble larger advertisements, which are referred to by their sheet count, including 24-sheet [ 9 ] billboards , and 30-sheet billboards.
A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an electroacoustic transducer [1]: 597 that converts an electrical audio signal into a corresponding sound. [2]
At this frequency, the voice coil is vibrating in the speaker's magnetic field with maximum peak-to-peak amplitude and velocity. The back EMF generated by this movement is also at its maximum. The electrical impedance of the speaker varies with the back EMF and thus with the applied frequency.
All speaker drivers have a means of electrically inducing back-and-forth motion. Typically there is a tightly wound coil of insulated wire (known as a voice coil) attached to the neck of the driver's cone. In a ribbon speaker, the voice coil may be printed or bonded onto a sheet of very thin paper, aluminum, fiberglass or plastic.
The sound was made into a mobile phone ringtone, which could not be heard by teachers if the phone rang during a class. [13] Mobile phone speakers are capable of producing frequencies above 20 kHz. [14]
Speaker enclosures are used in homes in stereo systems, home cinema systems, televisions, boom boxes and many other audio appliances. Small speaker enclosures are used in car stereo systems. Speaker cabinets are key components of a number of commercial applications, including sound reinforcement systems, movie theatre sound systems and ...