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I N S T R U C T I O N S

for

UNI-DIRECTIONAL MICROPHONE

TYPE 77-A

(MI-4040)

RCA Victor Division

RCA Manufacturing Company, Inc.

Camden, N. J., U. S. A.

Copyright 1936 by the RCA Manufacturing Company, Inc.

Instructions IB-25838

Summary of Contents for 77-A

Page 1: ...INSTRUCTIONS for UNI DIRECTIONAL MICROPHONE TYPE 77 A MI 4040 RCA Victor Division RCA Manufacturing Company Inc Camden N J U S A Copyright 1936 by the RCA Manufacturing Company Inc Instructions IB 25838 ...

Page 2: ...art of the ribbon An infinitely long tube would be the ideal impedance but this of course is im possible Instead an ingenious labyrinth which gives practi cally the same effect is used While this labyrinth has a finite length the desired damping of reflection is obtained by filing it very loosely with sound absorbing material e result is that the upper half of the ribbon becomes an efficient pressure...

Page 3: ...ssure operated microphone and re sults from the manner in which the velocity operated and the pressure operated parts of the ribbon add together Without going into mathematical expressions for these volt ages it is possible to obtain a picture of the action from a con sideration if the three patterns shown in Figure 2 In this illustration a is the directional pattern of a velocity micro phone b is...

Page 4: ...er the result will be practically zero output if their circuits are out of phase at the overall mixer To check the phasing of two or more microphones connected in a single pick up place the units close together two at a time with the attenuators mixers turned to the off position Turn on the attenuator of one microphone to some arbitrary position where the output will be distinctly audible or regist...

Page 5: ...microphone possesses a distinct advantage By placing the microphone with its dead side toward the audience and close to the footlights or in an equivalent position the 20 dB discrimination will provide the desired attenuation of audience noise while the broad pick up angle useful through nearly 150 degrees will afford pick up of the whole stage or that part of the studio where the artists are locat...

Page 6: ...order to prevent this However if the microphone does not tend to creep it is not necessary to use the clamping screw When it is desired to lower the microphone stand the clamping screw should first be loosened then the inner tube of the microphone stand should be raised slightly while pressing the sliding column latch which projects at the side of the locking device is will release the lock and al...

Page 7: ......

Page 8: ...Tympani and Traps V3 8 Violas M Microphone H1 2 Harps T3 4 Trombones V4 6 Cellos H2 8 French Horns T4 1 Tuba V5 4 String Bass B 4 Bassoons Ob 3 Oboes V1 12 First Violins C 4 Clarinets T1 3 Trumpets V2 10 Second Violins Total 75 Musicians IB 25838 Photos of 77 A courtesy of Scott Henderson SO 867079 4 450 ...

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