The connection of Sennheiser condenser microphones and dynamic microphones as weil is carried out using the principle of voltage matching.. The advantages of this system are that neither impedance variations of the microphone output nor of the amplifier input exercise a noticeable influence on the total frequency response. The source impedance of the Senn heiser condenser microphone with A-B powering is so low (approx.

20 Q at 1000 Hz) that an amplifier input with an impedance of 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 microphones 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 microphone itself is protected from high frequency disturbance. It is, therefore, not necessary, even underthe most difficult conditions, to take

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

Senn heiser condenser microphones are polarised according to DIN standard i. e. when apressure signal strikes the capsule from the front, Pin 1 of the DIN-connector (resp. pin 2 of the Cannon connector) goes positive with reference to Pin 3. This should be considered when the amplifier input is being wired.

Connection to Amplifiers with balanced Inputs

In this case the microphone is simply connected to the input of an amplifier via a battery adapter MZA 15 or the power supply MZN 16 T.

Connection to Amplifiers with unbalanced Inputs

In many cases, for example most tape recorders, the input socket is unbalanced. In this case one side of the bälanced microphone output has to be earthed. Apart from cases where the microphone is being used for professional studio purposes, this is not critical, asthe large outputvoltage of the microphone combined with its low output impedance provides a large signal to noise ratio. Care should be taken, hQwever, that no multiple ground circuits are formed when the microphones are mounted on tripods etc.

Connection to Amplifiers with High Input Sensitivity

In 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, wh ich helps to increase the signal to noise ratio.

Connectlon to Amplifiers with Defined Input Impedances

Senn heiser studio condenser microphones can be connected directly to all amplifiers whose input impedance is larger than 200 Q. This is usual in the majority of cases. However, if the input impedance is 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 directly. The voltage should be

12 volts::!: 2 volts. It should be so stabilised and filtered, that the un-

weighted noise voltage is less than 5 f.tVand that the weighted noise components are less than 2 f.tV.The current consumption of the microphone is approximately 6 mA. According to the DIN standard the

feed resistors should be 2 x 180 Q. This means that approx. 2 volts are lost across the resistors.

i

"Tn--nn,

 

:

 

 

 

 

 

 

 

I

~Lnnnn:

 

 

 

 

 

 

 

rC..

:

'2

I

 

 

 

 

 

!~:

I

3

 

 

 

 

 

 

I

 

I

 

 

"r"b

 

,I

 

I

 

 

 

I

 

 

I

 

 

 

 

 

 

 

 

 

 

 

 

180Q

180Q

'nnl

A-BpoweringaccordingtoDIN45595

12V O+ . S

+12V

 

 

 

 

 

 

 

 

 

 

 

,.nTnnn..,

 

,

 

 

 

 

 

 

 

I

 

 

 

 

 

 

 

 

 

I

 

 

,

 

 

 

 

 

NF

 

I

 

 

,

 

 

 

 

 

 

 

I

 

 

,

 

 

 

 

 

+'c--

 

I

 

 

,

 

 

 

 

 

 

I

 

 

 

 

 

 

 

 

 

I

 

 

,

 

 

 

 

 

 

 

I

L

 

,

 

 

 

 

 

 

 

:

nn:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.12V

 

:---rn---n-

 

 

 

 

 

 

 

NF

 

I

 

 

I

/--~n'7--"

a 360Q

 

 

I

 

 

'

 

 

 

I

 

 

'

I

,

,

,

 

 

 

I

 

 

'

,

,

,

,

 

 

 

:

 

 

I

 

 

 

 

 

I:t

 

 

 

'

 

 

 

 

 

 

I

 

 

'

 

 

 

 

 

 

 

:

T __n.nn'

['

 

 

"r.'b

 

 

 

A-B poweringunbalanced connection

MK 12 + MH 126P48 = MKH 126 P48

 

The MKH 126 P 48 is designed for phantom powering. All Sennheiser

 

microphones designated MKH . . . P 48 and P 48-U are 48 V phantom-

 

powered according to DIN 45596. Either condenser- or dynamic micro-

 

phones from Senn heiser electronic employ the principle of voltage

 

matching. This "no load condition" has the advantage that neither

 

impedance variations of the microphone output nor of the amplifier input

 

have a noticeable influence on the total performance of the system

 

(e. g. frequency response). The source impedance of Senn heiser con-

 

denser microphones with phantom powering is extremely low (about

 

20 Q at 1000 Hz) so that the amplifier input impedance has only to be

 

at least 200 Q.

 

Senn heiser condenser microphones produce relatively large output

\

voltages exceeding 1 volt at 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

I

not contribute to the total noise level. The microphones are fitted with

RF filters wh ich ensure that no high frequency signals from the mic[o-

 

phone can affect the external circuitry and that the microphone itself is

 

protected from high frequency disturbance. 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.

 

Senn heiser condenser microphones are polarised according to DIN

 

standard i. e. when apressure pulse strikes the capsule from the fro"t,

 

Pin 1 of the DIN-connector (resp. pin 2 of the Cannon connector) goes

 

positive with reference to Pin 3. This should be considered when the

 

amplifier input plug is being wired for correct phasing.

 

Connection to Amplifiers with balanced Inputs

 

Phantom-powered microphones are generally to be connected to

 

balanced ground-free transformer inputs.

12

13