Mchugh Military AMM-68 User manual

- INSTRUCTION MANUAL -
MCHUGH MILITARY CONDENSER MICROPHONE
MODEL AMM-68
MCHUGH MILITARY CORPORATION
COSTA MESA, CA USA
TM - .875
The 3rd edition
Februray, 1984
MCHUGH MILITARY CORP.
- INSTRUCTION MANUAL -
MCHUGH MILITARY CONDENSER MICROPHONE
MODEL AMM-68
MCHUGH MILITARY CORPORATION
COSTA MESA, CA USA
TM - .875
The 3rd edition
Februray, 1984
MCHUGH MILITARY CORP.

MCHUGH MILITARY CONDENSER MICROPHONEMODEL AMM-68
1. General
The MCHUGH MILITARY CONDENSER MICROPHONE MODEL AMM-68 is a high fi del
ity, omni-directional microphone developed by McHugh Military engineer-
ing staff.
The excellent performance of the AMM-68 got great reputation in the en-
tire fi eld of acoustic concern when it was introduced, and it has been
used in world-wide broadcasting stations, fi lm studios, recording facili-
ties, etc., where superior characteristics and reliability is required,
owing to its stable function, excellent performance, simple operation and
rigid construction.
2. Description
2.1. The upper part of the microphone is a 19 mm capsule
mounted in the metal netting, and the lower part,
inside of the metal case, is a cathode-follower circuit incl-
duing an electron tube 5840. the entire internal assembly is
rigidly shielded against an external static fi eld.
The diaphragm of the microphone capsule is a very thin plastic
fi lm nickel plated. Since this diaphragm is mounted on the capsule so
that it may fet full damping effect accoustically, the condenser mi-
crophone model AMM-68 shows very excellent frequency perfor-
mance.
2.2. The microphone unit is connected to the POWER SUPPLY MODEL MM-312
through the MICROPHONE CABLE TYPE BLDN-5P.
The output signal from the AMM-68 is delivered from the connector
located on the side panel of the CP-3B.
2.3. The new power supply unit model MM-312 is an improved version
of the model MM-31 formerly used, providing more reliable components
and printed circuit construction for higher and uniform performance.
2.4. Connectors for input and output, selectors for frequency response
are provided on the front panel of the MM-312.
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MCHUGH MILITARY CORP.
MCHUGH MILITARY CONDENSER MICROPHONEMODEL AMM-68
1. General
The MCHUGH MILITARY CONDENSER MICROPHONE MODEL AMM-68 is a high fi del
ity, omni-directional microphone developed by McHugh Military engineer-
ing staff.
The excellent performance of the AMM-68 got great reputation in the en-
tire fi eld of acoustic concern when it was introduced, and it has been
used in world-wide broadcasting stations, fi lm studios, recording facili-
ties, etc., where superior characteristics and reliability is required,
owing to its stable function, excellent performance, simple operation and
rigid construction.
2. Description
2. Description
2.1. The upper part of the microphone is a 19 mm capsule
mounted in the metal netting, and the lower part,
inside of the metal case, is a cathode-follower circuit incl-
duing an electron tube 5840. the entire internal assembly is
rigidly shielded against an external static fi eld.
The diaphragm of the microphone capsule is a very thin plastic
fi lm nickel plated. Since this diaphragm is mounted on the capsule so
that it may fet full damping effect accoustically, the condenser mi-
crophone model AMM-68 shows very excellent frequency perfor-
mance.
2.2. The microphone unit is connected to the POWER SUPPLY MODEL MM-312
through the MICROPHONE CABLE TYPE BLDN-5P.
The output signal from the AMM-68 is delivered from the connector
located on the side panel of the CP-3B.
2.3. The new power supply unit model MM-312 is an improved version
of the model MM-31 formerly used, providing more reliable components
and printed circuit construction for higher and uniform performance.
2.4. Connectors for input and output, selectors for frequency response
are provided on the front panel of the MM-312.
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MCHUGH MILITARY CORP.

3. Specifi cations
3.1. Type: Condenser microphone.
3.2. Output impedance: 150 ohms, balanced, deviation + 20%
3.3. Microphone cable: Shielded 4 conductors cable with
connectors type 5P, length 5.4 meters
3.4. Output receptacle: Type 3P.
3.5. Finish: Microphone - 6061 brushed aluminum
Power supply - Mil. Spec. green enamel.
3.6. Tube: 5840
3.7. Dimensions: Refer to fi g. 1 and 2.
3.8. Weights: Microphone - 91.7 g,
Power supply - 2.21 kg.
Microphone Cable - 390.5 g.
Total Weight - 3.29 kg.
3.9. Power requirements: AC 117 volts
60 cps, 10 VA
3.10. Power cable: 1.8 meter length UL cord.
Weight - 148 g.
4. Performance characteristic
4.1. Directivity: Omni-directional - refer to fi g. 3.
4.2. Frequency response: Omni-directional - refer to fi g. 4
Frequency range: 30 - 10,000 cps
within 5 db.
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MCHUGH MILITARY CORP.
3. Specifi cations
3. Specifi cations
3.1. Type: Condenser microphone.
3.2. Output impedance: 150 ohms, balanced, deviation
+
20%
3.3. Microphone cable: Shielded 4 conductors cable with
connectors type 5P, length 5.4 meters
3.4. Output receptacle: Type 3P.
3.5. Finish: Microphone - 6061 brushed aluminum
Power supply - Mil. Spec. green enamel.
3.6. Tube: 5840
3.7. Dimensions: Refer to fi g. 1 and 2.
3.8. Weights: Microphone - 91.7 g,
Power supply - 2.21 kg.
Microphone Cable - 390.5 g.
Total Weight - 3.29 kg.
3.9. Power requirements: AC 117 volts
60 cps, 10 VA
3.10. Power cable: 1.8 meter length UL cord.
Weight - 148 g.
4. Performance characteristic
4.1. Directivity: Omni-directional - refer to fi g. 3.
4.2. Frequency response: Omni-directional - refer to fi g. 4
Frequency range: 30 - 10,000 cps
within 5 db.
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MCHUGH MILITARY CORP.

4.3. Output level:
(1) The effective output level is defi ned as the ratio in db of the power
available from the microphone to 0.001@, on the sound pressure level of
10 ubar.
The calculation is based on the nominal microphone impedance.
(2) 0 db = 1 volt/10 ubar.
(3) EIA standard.
4.4. Signal to noise ratio : More than 60 db on the 1000 cps,
10 ubar sound.
5. Construction
The model AMM-68 consists of following items.
1. AMM-68 microphone with case.
2. MM-312 power supply.
3. BLDN-5P microphone cable, 5.4 meters long with connectors
4. Carrying case. (Ammo type)
5. Accessories.
a. Fuse, 1.0 A 1 pc
b. Pilot lamp, 117V 1
c. Output connector, 3P 1
d. Instruction manual 1 each
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MCHUGH MILITARY CORP.
Output
impedance
Effective
Output Level
Open Circuit Voltage EIA Rating
150 ohms
dbm (1) db (2) mV GM (3) dbv
-53.0 -60.0 1.0 -145.8
4.3. Output level:
(1) The effective output level is defi ned as the ratio in db of the power
available from the microphone to 0.001@, on the sound pressure level of
10 ubar.
The calculation is based on the nominal microphone impedance.
(2) 0 db = 1 volt/10 ubar.
(3) EIA standard.
4.4. Signal to noise ratio : More than 60 db on the 1000 cps,
10 ubar sound.
5. Construction
The model AMM-68 consists of following items.
1. AMM-68 microphone with case.
2. MM-312 power supply.
3. BLDN-5P microphone cable, 5.4 meters long with connectors
4. Carrying case. (Ammo type)
5. Accessories.
a. Fuse, 1.0 A 1 pc
b. Pilot lamp, 117V 1
c. Output connector, 3P 1
d. Instruction manual 1 each
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MCHUGH MILITARY CORP.
Output
impedance
Effective
Output Level
Open Circuit Voltage
EIA Rating
150 ohms
dbm (1)
db (2)
mV
G
M (3) dbv
-53.0
-60.0
1.0
-145.8

6. Operation
6.1. The microphone model AMM-68 is used together with the power
supply model MM-312 which is connected to the AMM-68 through
the microphone cable BLDN-5P.
The length of the microphone cable type BLDN-5P supplied is
5.4 meters, however, the distance between these two units may
be prolonged to up to 60 meters without giving any effect to the
performance.
6.2. The output signal from the microphone is delivered from the
3 P connector on the front panel of the MM-312.
6.3. The power supply is initially set at the factory for the line voltage
(117 VAC).
6.4. It may be noticed that there exist some noise when the switch
is on after long time of unused period or in rainy season, but
this noise will be disappeared after several minutes of operat-
ion, and the set will show perfect performance.
6.3. Do not turn on the power without connecting the microphone to
the powwer supply, or do not disconnect the microphone while
the power is on.
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MCHUGH MILITARY CORP.
6
. Operation
. Operation
6.1. The microphone model AMM-68 is used together with the power
supply model MM-312 which is connected to the AMM-68 through
the microphone cable BLDN-5P.
The length of the microphone cable type BLDN-5P supplied is
5.4 meters, however, the distance between these two units may
be prolonged to up to 60 meters without giving any effect to the
performance.
6.2. The output signal from the microphone is delivered from the
3 P connector on the front panel of the MM-312.
6.3. The power supply is initially set at the factory for the line voltage
(117 VAC).
6.4. It may be noticed that there exist some noise when the switch
is on after long time of unused period or in rainy season, but
this noise will be disappeared after several minutes of operat-
ion, and the set will show perfect performance.
6.3. Do not turn on the power without connecting the microphone to
the powwer supply, or do not disconnect the microphone while
the power is on.
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MCHUGH MILITARY CORP.

MCHUGH MILITARY CORP.
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MCHUGH MILITARY CORP.
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MCHUGH MILITARY CORP.

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23.93mm
23.75mm
131.83mm
101.6mm
22.3mm
MCHUGH MILITARY CORP.
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23.93mm
23.75mm
131.83mm
101.6mm
22.3mm
MCHUGH MILITARY CORP.

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MCHUGH MILITARY CORP.
Pilot Lamp
Power Switch
A.C. Connector
Connector for
Signal Output
Connector for
Microphone Cable
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MCHUGH MILITARY CORP.
Pilot Lamp
Power Switch
A.C. Connector
Connector for
Signal Output
Connector for
Microphone Cable
Microphone Cable

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MCHUGH MILITARY CORP.
258.48mm
288.65mm
- 9 -
MCHUGH MILITARY CORP.
258.48mm
288.65mm