that when the microphones are mounted ontripods etc. no multiple earth circuits are formed.

Connection to amplifiers with high input sensitivity

If the amplifier being used has a very high input sensitivity, i. e. when it is normally intended for use with dynamic microphones, it can be necessary to reduce the output voltage from the microphone by means of a voltage divider. This should be built into the microphone cable at the amplifier input. By this means the large signal on the microphone cable is maintained up to just before the amplifier, which helps to increase the signal to noise ratio.

Connection to amplifiers with defined input impedances

Senn heiser studio condenser microphones can be connected direct to all amplifiers whose input impedance is larger than 200 Q. This is usual in the majority of cases. Should, however, the input impedance be smaller than 200 Q, a resistor of appropriate value should be placed in series with the microphone so that it "sees" at least 200 Q. The

voltage division caused by this series resistor must of course be considered.

The same method can be used when a

higher output impedance of the microphone is demanded. In this case again, aseries resistor can be used to provide correct matching.

Connection to amplifiers with powering facilities

If an appropriate voltage source is available

in the amplifier the condenser microphone

can be powered direct. The voltage should be 12 volts::!:: 2 volt. It should be so stabi-

lised and filtered, that the unweighted noise voltage is less than 5 I-lVand that the weighted noise components are less than 2 I-lVolts. The current consumption of the

microphone is approximately 5 to 6 mA.

According to the DIN standard the feed

resistors should be 2 x 180 Q ::!:: 1 %. Thismeans that approx. 2 volts are lost across the resistors.

The circuit of the MKH 435 is so dimen-

sioned that a supply voltage tolerance of 12 volts::!:: 2 volts is permitted.

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