Schoeps Flexi-set with CMC 6, MK 4 and MK 21 Capsules

Schoeps Flexi-Set with CMC 6, MK 4 and MK 21 Capsules

The CMC 6 Microphone Pre-amplifier

The capsules of condenser microphones can't be connected directly to microphone cables or inputs; a microphone amplifier is required in between. Thus a complete microphone of the Colette series comprises any of the twenty available types of capsules combined with an amplifier. The CMC 6 U is designed for standard 48- and 12-Volt phantom powering. Its circuitry recognizes the supply voltage and adjusts itself automatically. Its performance characteristics remain essentially the same either way; mainly, the difference is that the current drawn at 12 Volts is greater than at 48 Volts. However, the 12-Volt mode consumes less power and might be preferred for battery-powered recording.

The microphone amplifier is responsible for providing the necessary electric charge to the capsule, without which it would be unable to generate a signal. Since the capsule's output signal is very weak (Hi-Z), it must be amplified. In order for the microphone's output to cleanly reach the next stage in the signal chain, it must undergo balancing and impedance matching before transmission. The CMC 6 incorporates a balanced, direct-coupled class-A amplifier, yielding a low output impedance, high RF shielding, and minimal distortion.

The MK 4 Cardioid Capsule

The MK 4 has been a reference microphone for years in a wide variety of recording situations.

Due to its transparent sound character and excellent attenuation of rear-incident sound, it reproduces sound sources very naturally. This has given the MK 4 a reputation as a universal "problem solver" even in difficult recording situations.

Its flat frequency response, and the constancy of its directional pattern for all frequencies, are the basis of the MK 4’s sound quality. Even in the diffuse sound field its frequency response is flat, with a slight increase at 10 kHz compensating for high-frequency losses in the room.

Thus the sound image is transparent for direct-arriving sound, for sound arriving from the side, and for diffuse sound in the room (reverberation).

The MK 4 is a classic small-diaphragm microphone with all the advantages of this microphone type. Its frequency response and the consistency of its polar diagram from low to high frequencies are exemplary.

Like all SCHOEPS capsules, the MK 4 achieves its flat frequency response solely by its mechanical architecture, without any electronic filtering.

As a pressure gradient transducer, the MK 4 has a single diaphragm that is exposed to the sound from both the front and rear. The side sound inlets must therefore never be covered.

The “reach” (distance factor) of a classic cardioid such as the MK 4 is about 1.7 times that of an omnidirectional microphone. Thus even at greater distances from the sound source, direct sound can be obtained. The advantages of the MK 4 are shown especially when mixing several microphone signals - pickup of sound from the side is reduced in level but not subject to coloration.

At 90° the attenuation of the MK 4 is 6 dB, and at 180°, some 20 to 30 dB. Diffuse-incident sound is picked up 4.8 dB lower in level than front-arriving sound.

The MK 21 Wide-Cardioid Capsule

The directivity of the wide cardioid lies between the omni and the cardioid. The idea behind their development is to combine the advantages of these two patterns. The low-frequency behaviour of the MK 21 is better than that of the cardioid, and proximity effect is less pronounced. The wide cardioid polar pattern is extremely consistent across the frequency range. Laterally-arriving direct sound and reflections are picked up without added coloration. The MK 21 is a very well-liked capsule. It is preferred when a slight directional effect and a warm, natural sound image are desired. Over the years it has become an integral part of the audio engineer's toolkit.