The connection of Sennheiser condenser microphones and dynamic
microphones asweil iscarried out using the principle of voltage matching..
The advantages ofthis system arethat neither impedance variations ofthe
microphone output nor of the amplifier input exercise anoticeable
influence on the total frequency response. The source impedance of the
Senn heiser condenser microphone with A-B powering isso low (approx.
20 Q at1000 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 1volt 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 notcontribute 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 alsothat
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 1of the DIN-connector (resp. pin 2 of the Cannon connector) goes
positive with reference to Pin3. 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. Inthis case one side ofthe bälanced microphone output has
to be earthed. Apart from cases where the microphone is being used for
professional studio purposes, this is notcritical, asthe large outputvoltage
of the microphone combined with its low output impedance provides a
large signal tonoise 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
Inthe amplifier being used has avery high input sensitivity, i.e. when itis
normally intended for use with dynamic microphones, it can be necessary
to reduce the output voltage from the microphone by means of avoltage
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 upto just before the amplifier, which 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 allamplifiers 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 isdemanded. Inthis 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-
12
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.
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MK 12+ MH126P48 = MKH126P48
The MKH 126 P48 is designed for phantom powering. All Sennheiser
microphones designated MKH . . . P48 and P48-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 Sennheiser 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 1volt 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
not contribute to the total noise level. The microphones are fitted with
RF filters which 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 ofthe 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 Pin3. 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.
13
