neumann.berlin
the microphone company
M 49 –The First Remote Controllable
An important step forward in microphone technology was
made with the model U 47. Its dual diaphragm capsule
M 7, active on both sides, made possible the first condens-
er microphone with switchable polar patterns. The ques-
tion arose, whether it could be possible to change the char-
acteristic during recording.
The relevant patent of Dr. Grosskopf reads: “Thus... the
influence of exaggerated re-
verberation can be dimin-
ished ... the recording dis-
tance ... can be increased
without getting a vague tim-
bre ... It is therefore an ur-
gent need for the recording
technique to easily exchange
microphones with different
polar patterns ...” The objec-
tive was to avoid an exchange
of microphones or capsules
and to remotely control the
microphone’s
directional
pickup pattern. For this pur-
pose it is important that the
output of the microphone
remain fairly constant and independent of the selected pat-
tern. The only switchable pattern microphone existing at
that time, the Neumann U 47, exhibits an increase in the
output by 5 dB when switched from omni to cardioid. In
the cardioid position the rear half of the capsule in the U 47
was simply electrically disconnected. As a consequence, the
output of the rear capsule and the attenuation of the front
via the fixed parallel capacitance of the rear were avoided.
Available were portable and rack mounted versions of the
power supplies. Due to the many supply voltages the M 49
microphone was equipped with an 8-pole connector. As
tube, in the early versions, a directly heated triode MSC 2
made by Hiller was employed, which later was succeeded
by the Telefunken AC 701 (k). The mechanical construc-
tion provided means for the suppression of structure born
noise. The amplifier was mounted on a solid rubber disk,
mechanically isolating the amplifier from the housing. In
addition, the microphone capsule was mechanically decou-
pled by means of a swing-metal shock mount. This meth-
od was incorporated later in most of the succeeding Neu-
mann microphones.
“Comfortable” pattern con-
trol for the new M 49 micro-
phone was achieved by keep-
ing both capsule halves con-
nected to the impedance
converter with regard to the
signal, however, insulated
from each other with regard
to the DC bias. The front di-
aphragm is polarized with a
constant voltage of 60 Vdc,
The M 49 was introduced to the German Radio Broad-
casters in 1952. Because of its unprecedented versatility it
conquered the international recording studios rather quick-
ly. Due to the innovative feature “remote pattern control”
it found widespread application as the important main mi-
crophone above large orchestras. Other applications were
as a spot microphone for wind and string instruments, for
piano and as the favorite announcer’s microphone.
while the bias for the rear di-
aphragm is adjustable from
0 Vdc to 120 Vdc. This al-
lows the polar pattern to be-
come variable between omni through cardioid to figure-8
maintaining a practically constant sensitivity. The power
supplies for the model M 49 microphones included a po-
tentiometer with a pointer knob and a corresponding scale.
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