NOTE: In general, high impedance microphones are used for public address
installations and consumer type tape recorders.
(9) Electret Condenser Microphone (Lavalier). The microphone element is attached to the
perfomer utilizing the supplied tie clasp. The microphone is comprised of two elements, the microphone
head and the battery/transformer housing, interconnected by 6 feet of miniature cable. The
battery/transformer housing is clipped to the performer's belt. This microphone is placed at hands'
length from the performer's mouth to obtain optimum sound quality.
NOTE: Cable Length. The effect of microphone cable length directly relates to
the impedance and the application of the sound system. The metallic shielding in
a microphone cable forms a capacitance with the inner conducting wires which is
added to the capacity between the wires themselves. This is the same as placing a
capacitor across the line; the higher the impedance used, the greater will be the
shunting effect across the line which will cause a loss of high frequency response.
Cable lengths must be considered when using high impedance microphones. The
effect of any cable length is negligible for low impedance microphones. A
general rule is to use a low impedance microphone for any cable run over 25 feet.
Low impedance must be used in any form of communications where the operator
works at a point remote from a microphone amplifier, since medium and high
frequencies are very important for crispness and intelligibility of speech.
i. Operator Maintenance of Microphones, Microphones Cables and Connectors.
(1) Inspect the microphone, microphone cables and connectors to insure
(a) Wind screens are in place and serviceable.
(b) Pickup element is serviceable.
(c) Microphone housing is not bent or broken.
(d) Connector pins are not bent, broken or corrected. If connector pins are broken,
(e) Cables are clean and wire shielding is unbroken. (Clean with water, mild soap and a
sponge or cloth.)
(2) Clean and service microphones, microphone cables and connectors in accordance with
the manufacturer's manual.