マイクロフォンアンプ
- balanced, very low-impedance output
- can be used with very long cables (several hundred meters)
- can be used with Active Accessories for miniaturization and special applications
convert the extremely high-impedance signal from the capsule to a very low-impedance one suitable for transmission through a microphone cable. Several versions are available which differ only in their powering, connectors, output levels and surface finishes. They all feature a symmetrical class-A output stage with neither coupling condensers nor an output transformer. This design helps them to achieve extremely low distortion and light physical weight, while their very low output impedance helps make them insensitive to electrical interference. On the choice of amplifier type:
If a recording device has balanced inputs but lacks phantom powering, it may be possible to add 12 Volt powering rather easily by using a supply voltage that is already present internally. In most cases 48 Volts would need to be generated with a voltage multiplier circuit, which is more difficult to implement. That is why we recommend the CMC 6, which works with both 12 V and 48 V phantom powering so long as the relevant standard is followed.
If it is certain that 48 Volt phantom powering will be available in all foreseeable recording situations, the CMC 5 should be fully satisfactory. In addition to the CMC 6's dual-voltage circuitry versus the CMC 5's single-voltage circuitry, the two amplifiers differ in their response at the very bottom of the audio frequency range. The CMC 5 rolls off below 30 Hz, while with digital recording in mind, the CMC 6 is essentially flat to 20 Hz.
The CMC 3 is designed for 12 Volt phantom powering. If necessary it can also be driven from certain 48 Volt phantom supplies, but it will draw significantly more current than a CMC 5 or CMC 6 without offering any particular advantage for doing so (a CMC 3 draws 11 mA at 48 V).
The CMC 4 works only with 12 Volt parallel powering (“T-feed“), which is rarely encountered nowadays except in video and film sound.CMC 6 CMC 5
(12 V and 48 V (48 V phantom
phantom powering)
powering)
CMC 3 CMC 4
(12 V phantom 12 V parallel
powering) powering)
Special Versions
Please note: The two amplifiers in a stereo pair of microphones should always be of the same type.
CMC 6 Ug“xt“ ? the 40 kHz Version
This version is indicated by the letters “xt“ engraved on the microphone's output socket as shown at left. It extends the frequency response of the axially addressed Colette capsules beyond 40 kHz.
Prospectus (PDF, 4,8 MB)
Further capsules which are extended up to 40 kHz in range by the CMC 6 xt:
all pressure transducers (omnis) with the switchable MK 5 capsule (omni/ cardioid) included,
both wide cardioids (MK 21, MK 21 H),
supercardioid MK 41
CMC “+5dB”
(Formerly marked with a blue dot.)
The sensitivity of a microphone using this type of microphone amplifier is 5 dB higher. The signal-to-noise ratio of the microphone itself remains nearly unchanged. The maximum sound pressure level the microphone can then accept is reduced by 5 dB.
The risk of overloading the input of the following device when high sound pressure levels are encountered is also increased.
This version might be chosen in order to raise the microphone's signals above the noise level of the equipment to which it will be connected, and/or for working with sounds that occur mainly at low levels.
CMC “linear”
(Formerly marked with a dash.)
CMC microphone amplifiers normally have a gradual rolloff below 30 Hz (20 Hz in the CMC 6) to guard against infrasonic disturbances from various sources such as air movement and vibration. However, when using pressure (omnidirectional) transducers, particularly with digital recording, it can be desirable to pick up frequencies below 20 Hz without attenuation. The special technology of the CMC microphone amplifiers makes this possible; on request we can deliver microphone amplifiers with response that is flat to as low as 3 Hz.Caution must be advised with respect to infrasonics, however. Since pressure transducers can pick up very low frequencies, ventilation systems in large spaces (churches, concert halls) can create a problem. With pressure gradient transducers the risk is even greater. They are far less sensitive to very low frequency sound, but respond much more strongly to unwanted low-frequency stimuli such as air currents and solid-borne noise. Although such signals may be below the audible range of frequencies, they can overload electronic circuitry and produce severe distortion.
Included accessory with every CMC microphone amplifier:
polished wood case for two microphones
Type designation of a complete microphone:
CMC 6 4 U g 6 powering： 12 V - 48 V phantom 4 capsule type： MK 4 U connector： XLR-3M g surface finish： matte gray
A note of caution:
The current required by the SCHOEPS class “A“ output circuit falls well within the limit of 10 mA set by the prevailing standard (DIN EN 61938, July 97, formerly DIN IEC 268-15 and DIN 45 596). However, certain commercially available power supplies, preamplifiers, and mixing desks ? mostly older, but some more recent ? may fail to meet this standard. Such units may not be able to power SCHOEPS microphones adequately, especially where headroom at high SPL is desired. Where doubt exists, equipment should be checked to verify its suitability for professional work with SCHOEPS microphones.
The PHS 48 accessory test plug can be helpful in testing equipment quickly and easily to see whether it is compatible with SCHOEPS 48 Volt phantom-powered microphones.
