The Electro-Voice Model CS15
cardioid electret condenser microphone
Photo courtesy of Marc Woodward
Description and Applications
The Electro-Voice Model CS15 is a professional remotely powered electret condenser cardioid microphone designed especially for recording, broadcast and sound reinforcement applications where the smooth, wide-range response of a studio microphone is desired. The machined steel case and rugged internal design enable the CS15 to withstand abuse.
The CS15, being a true cardioid microphone, offers greatest rejection at 180° off axis, directly to the rear of the microphone. Like all other condenser cardioid microphones, the CS15 is a single D cardioid. Due to the proximity effect in all single D cardioids, the low-frequency response of the CS15 is dependent upon the distance from the sound source to the microphone as illustrated in Figure 2.
Maximum bass response is produced in close-up use with the microphone one quarter of an inch from the sound source (Figure 2A). Minimum bass response is experienced at distances greater than twenty-four inches (610 mm) (Figure 2C). By working closer to the microphone than otherwise might be natural, the human voice will sound more robust, although intelligibility may be adversely affected.
The CS15 Condenser Microphone requires a remote power supply in order to operate. Power may be obtained from a microphone input equipped with remote powering (48 VDC) or from an accessory power supply placed in the line between the microphone and mixer input.
The PS8 Remote Battery Power Supply is designed to power the CS15 and should be placed in the microphone line between the microphone and the mixer. Care should be exercised to make certain that the PS8 is installed with its female connector facing the microphone. Because the PS8 employs a transformer with a center-tapped secondary, attenuator pads, filters and other similar devices may be inserted between the PS8 and the preamplifier input (not between the PS8 and the CS15). A removable blast filter (Model 315) is supplied with the CS15. This filter is designed to reduce P-popping and blasting commonly encountered in close-miking applications.
The generating element of a condenser microphone is a capacitor, with one of its plates comprising the microphone’s moving diaphragm; the other plate being the stationary back plate. When a charge is applied to the diaphragm, and changes in air pressure move the diaphragm, an output voltage is generated. All condenser microphones require a charge or difference of potential between diaphragm and back plate. Early condenser microphones achieve this by employing an external DC power source of approximately 200 volts. This system was awkward to use.
Today, condenser microphones operate from voltages of 48 volts and less. There are two methods of utilizing these lower voltages. One method increases the input voltage by employing some sophisticated electronic circuitry. Another method is to apply the 48 volts directly to the diaphragm, thus making the dynamic range and sensitivity of the microphones totally dependent upon the stability of the 48-volt supply. Still other methods have been devised.
In recent years, materials and techniques have been developed which allow placing a permanent charge on the condenser microphone capacitor element (diaphragm). This ability to permanently charge a material is known as the electret phenomenon. With a permanent charge on the diaphragm, the only voltage needed is to power the impedance converter. Because the output of any condenser microphone is extremely high in impedance, a means to convert the small fluctuations in capacitance into a usable output voltage is needed. The impedance converter provides this function and generally consists of a field effect transistor and its associated circuitry as shown in Figure 3.
Text and illustrations are from the Electro-Voice Model CS15 data sheet, Part No. 535539–445.
Download the data sheet for this mic.