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Low-cut Filters
LC 60 U (60 Hz), LC 120 U (120 Hz)
- active High-pass Filters for phantom-powered microphones, in particular CCM Compact Condenser Microphones and CMC microphones of the Colette Modular System
- for standard phantom power, 12 V or 48 V
These electronic filters can be inserted anywhere in the microphone cable path.
With a rolloff of 18 dB/ octave, the LC 60 U suppresses low-frequency acoustic interference (e.g. wind noise, or solid-borne infrasonic noise such as handling noise during boom operation) without detracting from the sound quality of voice recordings. Under extreme conditions the LC 120 U can be used, though it may have an audible effect on the sound of a voice. Both filters can help prevent overloading the input circuit to which a microphone is connected ? a problem which occurs more often than many people realize.
The specifications of the SCHOEPS microphones (sensitivity, noise, source impedance) remain nearly unchanged with the LC.
These low-cut filters are suitable not only for SCHOEPS microphones but also for phantom-powered microphones of other manufacturers, provided that they have a current consumption of at least 2 mA. Otherwise the maximum sound pressure level would be reduced.Please note:
The use of two LC in series is possible, particularly with SCHOEPS microphones, but is not recommended. The cutoff frequency would be raised, and the maximum output level with 12 Volt operation would be lowered. In no case should three LC be cascaded, especially if the microphones have less than 4 mA current consumption
Technical specifications
Active Low-Pass Filter, e.g. for OCT
LP 40 U
- for adapting the signal from a pressure (omnidirectional) microphone to fill in the bass region of directional microphones (especially with the OCT system)
- for phantom-powered microphones
The low-frequency response of any directional microphone is inherently inferior to that of omnidirectional (pressure) microphones. When using directional microphones, one can extend the low-frequency response by adding in signals from omnidirectional microphones that have been low-pass filtered with a device such as the LP 40.
The LP 40 filter is designed to extend the frequency response of the SCHOEPS supercardioid (MK 41(V) or CCM 41(V)) with the lowest possible ripple. This makes it ideal for use with the OCT front surround system; it can also be used to extend the response of directional microphones with other patterns.
Technical specifications
Attenuators
Signal distortions at high sound pressure levels have two main causes:
1. Overload of the microphone
Under extreme conditions, even a SCHOEPS Colette Series microphone can be overdriven by very high sound pressure levels. Here the limiting factor is not the capsule but the microphone amplifier. The overload point ranges from 128 ? 135 dB-SPL, depending on the capsule and the amplifier type (e.g. 5 dB lower with the “+5 dB“ version).
In these situations the signal level at the amplifier input may be attenuated by inserting a DZC between the capsule and the microphone amplifier or the Active Accessories.2. Overload of the input of the device to which the microphone is connected
If the microphone is not being overloaded but its output level must be reduced, it would be far better to use an MDZ in-line attenuator than a DZC. The MDZ should be placed at the end of the cable farthest from the microphone, where it will not only help to prevent preamp overload but also to reduce any interference picked up in the microphone cable and the noise of the microphone itself. (Never place an in-line attenuator at the microphone end of a cable. Doing so would increase the relative strength of any induced interference, and increase the rate of signal loss in longer cables due to the higher source impedance.)
Attenuator
MDZ 10, MDZ 20
- for phantom- or parallel-powered microphones
- ca. 10 dB/ 20 dB constant attenuation
- avoids overloading sensitive inputs
- to be inserted between the microphone cable and the phantom-power supply
- does not reduce the microphone's signal-to-noise ratio
The MDZ can also prevent the input impedance of a preamp from loading down a microphone; with it in place, the minimum load impedance for a CMC-series amplifier is reduced from 600 to 200 Ohms. It can also be useful when driving transformer-equipped inputs designed for 200 Ohm sources, which may develop high frequency response errors when driven by much lower impedances, particularly if the input transformer has a high turns ratio.
Please note:
With parallel-powered microphones, the MDZ must be inserted between the powering unit and the output cable.Connectors: XLR-3F/ XLR-3M
Dimensions: length: 75 mm; max. diameter: 19 mm
Color: black
Test Plug PHS 48 - quick test of 48 V phantom powering (current)
- indication by a green LEDThe PHS 48 can be plugged into a microphone input or cable that carries 48 Volt phantom power, to verify that sufficient current is available to power a SCHOEPS microphone. According to the standards, a 48 V phantom powered microphone may draw a current of up to 10 mA per channel. SCHOEPS CMC 5, CMC 6 and CCM microphones actually need only 4 mA (ca. 5 mA if Active Accessories are used), so the PHS 48 tests for approximately this amount of available current at the required voltage level.
Any trim, gain, or volume controls should first be set to their minimum position, to avoid noise and potential damage. Then, while all other microphones are already connected the test plug is attached to the socket which is intended to power the SCHOEPS microphone. The green LED in the PHS 48 will light and remain lit if the test result is positive.
Connector: XLR-3M
Dimensions: length: 53 mm, diameter: 19 mm
Surface finish: nickel
Cables can be found here...
