Speaka Grill : July 25, 2008
Image Data
File Name: 20D_38396
Model: Canon EOS 20D
Lens: Canon EF 100mm F/2.8 USM Macro
Date: 07.24.08 11:42pm
Focal Length: 100mm (160mm)
Shutter: 1/2 s
F-Stop: F4
ISO: 200
Ex Bias: +4/3
Program: Aperture priority
Metering Mode: Evaluative
Flash: Off
Focus Mode: Manual focus
File Name: 20D_38396
Model: Canon EOS 20D
Lens: Canon EF 100mm F/2.8 USM Macro
Date: 07.24.08 11:42pm
Focal Length: 100mm (160mm)
Shutter: 1/2 s
F-Stop: F4
ISO: 200
Ex Bias: +4/3
Program: Aperture priority
Metering Mode: Evaluative
Flash: Off
Focus Mode: Manual focus
Alexander Graham Bell patented the first electrical loudspeaker as part of his telephone in 1876. Nikola Tesla reportedly created a similar device in 1881, but was not issued a patent. In 1898, Horace Short patented a design for a loudspeaker driven by compressed air. A few companies produced record players using compressed-air loudspeakers, however, these designs were significantly limited by their poor sound quality and their inability to reproduce sound at low volume. Variants of the system were used for public address applications, and more recently other variations have been used to test space equipment resistance to the very loud sound and vibration levels that launching rockets produce.
The modern design of moving-coil drivers was established by Oliver Lodge in 1898. The moving coil principle was patented in 1924 by Chester W. Rice and Edward W. Kellogg.
The modern design of moving-coil drivers was established by Oliver Lodge in 1898. The moving coil principle was patented in 1924 by Chester W. Rice and Edward W. Kellogg.