Some New RCA Photophone Studio Recording Equipment

An illustrated description is given of some new input equipment for sound recording. This equipment provides for mixing the audio outputs of four or eight microphones into the recording amplifier, which has two output channels. Some of the interesting features of this equipment are: (a) Constant impedance mixing, providing constant load on each microphone amplifier for all combinations of volume control settings, thus giving unchanging fidelity and a constant output level from each microphone channel for all combinations of volume control settings in the other channels: (b) Filter for eliminating low rumbles, caused by room vibrations, wind disturbances, etc., can be switched “on” or “off” at the mixer. This filter does not affect the fidelity above 100 cycles. (c) Recording amplifier, having two output channels, supplying two loads with no interaction between them. Each channel has a convenient switching arrangement for changing the output transformer ratio, making possible the operation of one, two, or three 500 ohm loads in parallel. (d) Each unit of the equipment is designed to mount on a standard relay rack or in an individual box equipped with handles for carrying.

Print ISSN

0097-5834

Published

1931-03

Content type

Original Research

DOI

10.5594/J13013