Co

of the Sennheiser condenser microphones with A-B powering is so low (approx. 20 Q)

that an amplifier input with an impedance oI at least 200 Q will be suitable.

Sennheiser condenser microphones produce relatively large output voltages, these can be up to 1 volt with maximum sound pressure levels. This has the advantage that even with long cables induced interference signals can be disregarded. Also the internal

noise produced by the microphone does not contribute to the total noise level. The mi-

crophones are fitted with high frequency filters, which ensure that no high frequency signals from the microphone can affect the external circuitry, and also that the micro-

,.one' itself isprotected from high frequency

~turbance.

It is, therefore, not necessary,

.

 

even under the most difficult conditions, to

take special precautions such as double screening of the cables or the provision of high frequency filters.

Sennheiser condenser microphones are po- larised according to DIN standard i.e. when

apressure signal strikes the capsule from

the front, Pin 1 goes positive with reference to Pin 3. This snould be considered when

the amplifier input plug is being wired.Connection to Amplifiers with Symmetrical Inputs

In this case the microphone is simply connected to the input of an amplifier via a battery adapter or the power supply MZN 5-1. For larger installations the power supply

MZN 6, which can feed up to six microphon es, can be used. It should be noted that this power supply is delivered without feed resistors and these must be added by the user.

Connection to Amplifiers with

Unsymmetrical Inputs

In many cases, for example most tape re-

corders, the input socket is unsymmetrical. In this case one side of the symmetrical microphone output has to be earthed. Apart from cases where the microphone is being

used for professional studio purposes, this

is not critical, as the large output voltage of

the microphone combined with its low output impedance provides a large signal to noise ratio. Care should be taken, however,

9