microphone, calibrated
Date: circa 1970
Inventory Number: 2003-1-0118
Classification: Microphone
Subject:
Maker: General Radio Company (1915-present)
Cultural Region:
Dimensions:
2.9 × 2.3 × 2.3 cm (1 1/8 × 7/8 × 7/8 in.)
Accessories: calibration chart, included in box.
Description:
A high quality condenser microphone made by the General Radio Company.
The microphone is enclosed in a cylindrical metal case with perforations on the top. The bottom end of the microphone has a threaded edge, and the back is open. Inside, a blue circuit board with two pins can be seen. Printed on the board is "51929" in white lettering.
The microphone is in a cardboard box and has a somewhat wrinkled calibration chart accompanying it, printed in black ink with a red chart line, certifying its calibration titled, "MICROPHONE CALIBRATION CERTIFICATE / GENERAL RADIO CO. CONCORD MASS. U.S.A. /RANDOM INCIDENCE / RESPONSE CHART." The chart is marked "Decibels," from -12 to +8 on the vertical axis and "Frequence in Hz" from 20 to 20K on the horizontal axis.
The microphone is stored in a small white cardboard box. The top flap of the box is hand inscribed in pen, "Gen Radio / 1" mike," and stamped in ink, "1560 9065"
The microphone is enclosed in a cylindrical metal case with perforations on the top. The bottom end of the microphone has a threaded edge, and the back is open. Inside, a blue circuit board with two pins can be seen. Printed on the board is "51929" in white lettering.
The microphone is in a cardboard box and has a somewhat wrinkled calibration chart accompanying it, printed in black ink with a red chart line, certifying its calibration titled, "MICROPHONE CALIBRATION CERTIFICATE / GENERAL RADIO CO. CONCORD MASS. U.S.A. /RANDOM INCIDENCE / RESPONSE CHART." The chart is marked "Decibels," from -12 to +8 on the vertical axis and "Frequence in Hz" from 20 to 20K on the horizontal axis.
The microphone is stored in a small white cardboard box. The top flap of the box is hand inscribed in pen, "Gen Radio / 1" mike," and stamped in ink, "1560 9065"
SignedMarked on chart: GENERAL RADIO CO. CONCORD MASS. U.S.A.
Inscribedprinted on circuit board: 51929;
printed on calibration chart: CHART NO. 1527-9649 / MICROPHONE CALIBRATION CERTIFICATE / GENERAL RADIO CO. CONCORD MASS. U.S.A. / RANDOM INCIDENCE / RESPONSE CURVE / 500 Hz SENSITIVITY / 0= -- 41.7 dB re 1 volt/N/m2 / (0= -- -1 61.7 dB re 1 volt/mu bar) / CAPACITANCE 331 pF / Microphone Type: 1560-9605 / Serial Number: 51929 / Date: / Used With / Type: / Serial Number: / Calibrations made at 23° C / The Calibration of this microphone was performed by comparison of a Western Electric Company Type 640AA Laboratory / Standard Microphone in accordance with Section 7 (Comparison Free Calibration) of the ANSI "Standard Method for / the Calibration of Microphones," S1.10, 1960. Our Calibration Laboratory maintains Laboratory Standard microphones that / are calibrated by the reciprocity technique as described in Section 4 (Absolute Pressure Calibration) of S1.10, 1960. In / addition, our standard calibrations are compared to calibrations performed by theNational Bureau of Standards;
inscribed on storage box: Gen Radio / 1" mike / 1560 9065
printed on calibration chart: CHART NO. 1527-9649 / MICROPHONE CALIBRATION CERTIFICATE / GENERAL RADIO CO. CONCORD MASS. U.S.A. / RANDOM INCIDENCE / RESPONSE CURVE / 500 Hz SENSITIVITY / 0= -- 41.7 dB re 1 volt/N/m2 / (0= -- -1 61.7 dB re 1 volt/mu bar) / CAPACITANCE 331 pF / Microphone Type: 1560-9605 / Serial Number: 51929 / Date: / Used With / Type: / Serial Number: / Calibrations made at 23° C / The Calibration of this microphone was performed by comparison of a Western Electric Company Type 640AA Laboratory / Standard Microphone in accordance with Section 7 (Comparison Free Calibration) of the ANSI "Standard Method for / the Calibration of Microphones," S1.10, 1960. Our Calibration Laboratory maintains Laboratory Standard microphones that / are calibrated by the reciprocity technique as described in Section 4 (Absolute Pressure Calibration) of S1.10, 1960. In / addition, our standard calibrations are compared to calibrations performed by theNational Bureau of Standards;
inscribed on storage box: Gen Radio / 1" mike / 1560 9065
FunctionMicrophone for capturing and transmitting sound.
ProvenancePrivate Donor, Troy, NY, 2003.
