The Sony Models C-55FET and C-55P cardioid condenser microphones – 1970
![Sony C-55P](https://coutant.org/sonyc55p/c55_full.jpg) The original C-55 above is battery-powered, and uses a DC-DC converter to provide polarization voltage to the condenser microphone capsule. The C-55P FET microphone omits the DC-DC converter, and polarizes the microphone capsule from the P48 powering. (An image of the Model C-55P FET can be seen below.)
General Description The Sony Model C-55P is a lightweight handy type uni-directional condenser microphone intended for broadcast or recording studio use, with features as follows.
- Phantom Powering System
The microphone is operated from an AC power source by using Sony AC Adapter AC-148A (optional). The shielded two-conductor microphone cable is used as both an audio signal cable and a DC power supply cable by connecting to the AC-148A. Positive DC current is supplied to the microphone through the inner two conductors of the cable, and negative DC current through the shield conductor.
![Figure 1-1](https://coutant.org/sonyc55p/fig1-1.gif)
- Low-Cut Switch
This switch has the following three positions: M for a flat frequency response, M1 for slight attenuation of low frequencies, and V1 for extreme attenuation of low frequencies.
![Figure 1-2](https://coutant.org/sonyc55p/fig1-2.gif)
- High-Cut Switch
This switch has the following two positions: Flat frequency response, and Attenuation in the frequency range higher than 5 kHz.
![Figure 1-3](https://coutant.org/sonyc55p/fig1-3.gif)
- Pad Switch
This switch has the following two positions: 0 for no attenuation, and -8 dB for eight decibels of attenuation over the entire frequency range, used for high-pressure sound pick-up.
![Figure 1-4](https://coutant.org/sonyc55p/fig1-4.gif)
- Capsule Angle Change
The capsule angle can be changed through 90 degrees vertically by pressing the two side buttons.
![Figure 1-5](https://coutant.org/sonyc55p/fig1-5.gif)
![Sony C-55P](https://coutant.org/sonyc55p/2.jpg) The Model C-55P FET microphone shown here has its rolloff selector ring in a different location from that of the Model C-55 seen at the top of this page, and does not have the “BATT” nor “OFF” switch positions. Images and a description of a P48 power supply designed and built by Rick Chinn can be viewed here. Use your “Back” button to return to this page after you view Rick’s work.
SPECIFICATIONS
Type: C-55P FET condenser microphone
Power Supply: Standard operating voltage; DC 48–54 V
Current Drain: Less than 2.5 mA
Frequency Response: 40–16,000 Hz ±2.5 dB
Output Level:
Pad switch Output Effective Open circuit EIA
position impedance output level output level rating GM
*(dBm) **(dB) ***(dB)
————————— ————————— ———————————— ————————————— —————————
0 250 Ω –49.8 –50 (3.16 mV) –141.8
–8 dB 250 Ω –57.8 –58 (1.25 mV) –149.8
*0 dBm = 1 mW/10 µbar, 1,000 Hz
**0 dB = 1 V/10 µbar, 1,000 Hz
***EIA standard SE–105
Directivity: Uni-directional
Output Impedance: 250 Ω ±20% at 1,000 Hz balanced
Noise Level: S/N ratio: more than 50 dB (1,000 Hz, 1 µbar)
Inherent noise: less than 24 dB-SPL
Wind noise† less than 43 dB-SPL
Induction noise of external magnetic field‡
less than 5 dB-SPL/milligauss
†The value measured by applying a wind of 6.6 feet/second velocity from all directions to the microphone. The mean value is taken and converted to the equivalent input sound level: (0 dB = 2 × 10-4 µbar)
‡The external magnetic field induction noise is measured with the microphone placed in the alternating magnetic field of 50 Hz, 1 milligauss. The maximum noise value is taken and then converted to the equivalent input sound level: (0 dB = 2 × 10-4 µbar)
Maximum Input Sound Pressure Level: 154 dB-SPL. This is the maximum input level which produces less than 1% wave distortion at the output with 1,000 Hz, and less than 1% intermodulation distortion at the output signal with 70 Hz to 7 kHz
Dynamic Range: 130 dB (0 dB = 2 × 10-4 µbar)
Semiconductors: 1 module, 1 transistor
Dimensions: 1.3 inch diameter × 6.56 inches length (33 mm diameter × 167 mm length)
Weight: 10 ounces (280 g) without cable
![Sony C-55P](https://coutant.org/sonyc55p/3.jpg)
![](https://coutant.org/sonyc55p/figure02.gif)
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![Identification](https://coutant.org/sonyc55p/id.jpg)
Numerous technical illustrations, including some not shown here, can be found in the three booklets that are available for downloading from the bottom of this page.
![Sony C-55P](https://coutant.org/sonyc55p/4.jpg)
![C-55P cover](https://coutant.org/sonyc55p/cover.gif) Download the C-55P Operating Instructions. Special thanks to Jim Zuehsow for this manual.
![Service Manual](https://coutant.org/sonyc55p/cover.jpg) Download the C-55P Service Manual. Special thanks to Ms. Kimberly Stewart of Sony Corporation for this manual.
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