Introduction The Inductor Microphone is the result of research and development toward the production of a low-priced mic, the characteristics of which are high quality, sensitivity, freedom from shock excitation troubles, minimum response to wind effects, compactness, and ruggedness.
This microphone is a pressure-operated mic of the moving conductor type. A single 0.010-inch aluminum conductor is rigidly coupled to a diaphragm and located between the poles of a permanent magnet with its length perpendicular to the magnetic lines of force. The ends of the conductor are connected to a transformer that matches the impedance of a 250 or 50 ohm line. Sound waves reaching the diaphragm vibrate the conductor within the magnetic ﬁeld set up by the magnet. The vibration of the conductor is in accordance with the sound vibrations and, occurring as it does within the magnetic ﬁeld, sets up a corresponding alternating electric potential across the primary of the microphone transformer. These minute voltages are subsequently ampliﬁed to the power level required for broadcasting.
Quality of Response The frequency response of the microphone is uniform over its useful operating range from 60 to 10,000 cycles. The variation of the frequency response characteristic with the direction of the incident sound is similar to that of any other pressure operated microphone of comparable size, in that response to higher frequencies is attenuated as the angle between the direction of the incident sound and the plane of the diaphragm is decreased.
The microphone and its transformer are enclosed within a sturdy and attractive metal case on the back of which is mounted a recessed male connector for the attachment of the microphone cable. The microphone case is ﬁtted with a perforated metal front cover which serves to protect the transmitter from mechanical injury and adverse wind effects. This assembly is pivoted in a fork, to which is attached a threaded ﬂange mounting by means of which the microphone may be fastened to the top of a microphone stand. A suspension mounting Type UP-4277 is also supplied with the microphone to permit the unit to be suspended overhead when desired.
Marian Anderson performs Erbarme dich, mein Gott by J. S. Bach. This link will transport you to a photo array on YouTube. Using the BACK button will be required to return to the mic site. Audio duration is eight minutes.