The Sony Model C-37P FET
Variable-Directivity Condenser Studio Microphone
The C-37P covers the entire frequency range with smooth frequency response and uniform directional characteristics. The use of the unique intermodulation distortion circuit in the FET preamplifier, plus wide dynamic range and remarkably low inherent noise level assure unexcelled performance.
Unique powering system
The C-37P can be phantom powered from an external DC power supply voltage (DC 48-54 V) without any additional conductors and cables. The phantom power system is an internationally accepted standard which permits complete interchangeability of microphones, regardless of type.
Uni- or Omni-directional characteristics are easily selected by switch.
The C-37P can be operated from an external power supply voltage using the Sony AC-148A Power Supply or equivalent.
Optional accessory Power Supply ac-148a
The optional Sony Model AC-148A will power up to twelve microphones when adapted for studio use.
Due to the use of a Phantom Power System, the C-37P must have balanced output connections. Therefore, use balanced-type cable for extending cable between the power supply and the C-37P.
Microphone cable length adjustment
When the microphone angle is changed, adjust the cable to its proper length.
- Pull out the bushing from the retainer
- Adjust the cable length
- Reinsert the bushing into the retainer
Directivity Select Switch
Directivity of the C-37P may be switched from cardioid to omni-directional by setting the Directivity Select Switch (located on the rear cage) to either the “U” or “N” position with the supplied screwdriver. The “U” represents the uni-directional (cardioid) characteristics; the “N” indicates the non-directional (omni-directional) characteristics. Note: To avoid undesirable microphone output noise caused when the Directivity Select Switch is moved, reduce the microphone amplifier level or select the directivity pattern before connecting the microphone.
Function Select Switch
The Function Select Switch has four functions: M provides flat (full range) frequency response. M1 provides slight low-frequency attenuation. V1 provides low-frequency attenuation. V2 provides severe low-frequency attenuation (roll-off). M, M1, V1, V2 can be selected to provide the best frequency response characteristics for the specific sound pickup circumstances.
To prevent overload of the impedance translator resulting from the pickup of extremely high-level sound sources, the pad switch (located on the center rear of the microphone) reduces the output level of the microphone capsule by approximately 8 dB. This allows even the highest sound levels encountered in practice to be reproduced without distortion. In general, set the switch to its 0 position. When the recording of high sound levels is necessary, set the switch to its –8 dB position. The output level of the microphone is reduced by approximately 8 dB.
Windscreen and shock mounting
The microphone grille is equipped with a windscreen which surrounds the capsule. The capsule is fully shock-mounted to eliminate the pickup of vibrations transmitted through the microphone stand.
Phantom power system
The C-37P utilizes the standard phantom power (DC 48-54 V) system. The phantom power system consists of a DC power source, the standard two-conductor shielded microphone cable and center-tap transformer of the C-37P. The Sony AC Power Supply Model AC-148A is recommended as an optional accessory. In this form of powering, the supply current (positive potential) is fed to the center tap of the power supply transformer, and is conducted symmetrically via the A and B conductors whose original function is to carry the microphone output signal. Then, this voltage is fed to the center tap of the microphone transformer. The negative potential is sent through the shield. The phantom powering DC voltage is completely isolated from the audio signal of the microphone, and has no adverse effect on the signal. This powering system offers the following advantages.
Interchangeability with other types of microphone
The outlet of the power supply transformer may be connected to any other type of microphone… condenser, dynamic, ribbon, etc… without causing noise, interference or deterioration of the signal, since no voltage difference occurs between the A and B conductors. Improper polarity connections of A and B conductors will not affect operation of the C-37P.
Simplified microphone setup
Once the powering system is set up, the C-37P is as convenient to use as any dynamic or ribbon microphone.
FET preamplifier circuit
The FET circuit of the C-37P assures extremely low intermodulation and total harmonic distortion. This circuit provides superior linearity and dynamic range. Intermodulation distortion remains less than 1% at the sound pressure levels up to 154 dB-SPL1, and total harmonic distortion remains less than 1% at 1 kHz. This circuit has an equivalent inherent noise level of less than 24 dB-SPL. Accordingly, an extraordinary dynamic range of 130 dB is obtained.
All circuit components are mounted on an epoxy-tetron printed board that is completely moisture proof and is protected by a dust cover. This assures stable operation even in the most humid operating conditions.
- 70 Hz and 7 kHz; 4:1 ratio. Applied to input of impedance translator
at a level which is equivalent to capsule output at 154 dB-SPL.
All text, photographs, and illustrations are courtesy of Sony Corporation.
Download the Operating Instructions for this mic.
Manual courtesy of Donald Setaro.