Sennheiser MKE 212 User manual

MKE 212
GEBRAUCHSANLEITUNG
INSTRUCTIONS FOR USE
INSTRUCTIONS POUR L‘USAGE

Acoustical Boundary Microphone MKE 212
The MKE 212 is an acoustical boundary microphone which utilizes the increase
in sound pressure on acoustically live surfaces and, due to its flush mounting into
the surface, does not pick up reflections on this surcface.
In the interest of better understanding, here a few explanations about the working
principle of the acoustical boundary microphone:
A microphone with no or only low directivity, positioned in the centre of a room,
will show irregularities in frequency response. This, the so-called comb filter effect,
is caused by reinforcements and cancellations of sound pressure between direct
and indirect, reflected sound. Picking up the sound with the same microphone
located a few millimeters from a live surface, e.g. a wall, gives in the ideal case an
in-phase addition of direct and reflected sound which results in an increase in
sound pressure of 6 dB, independent of frequency. Simulating this wall, or the
acoustically live surface with a metal disc or a similar device into which a pressure
microphone has been flush mounted creates a microphone which differs in two
ways from conventional pressure microphones:
왘Since there is always a pressure maximum directly at the boundary, the
phase relationship remains defined at any time.
왘Due to the negligible distance to the boundary, the microphone exhibits
no comb filter effect.
The effectiveness of the pressure zone depends on the size of the surface. On
small surfaces, the low-end cutoff frequency is very high; on large surfaces, it
drops correspondingly lower. Due to its dimensions of 185 mm x 165 mm, the
MKE 212, measured alone in the free field, demontrates this pressure increase
above approx. 1 kHz. In applications on the floor or at a wall, this pressure
increaseshiftstothelowestfrequencies.AcharacteristicofSennheiseracoustical
boundary microphone is the fact that the microphone capsule is mounted flush
with the surface. To eleminate futher reflections which again would cause
irregularities in frequency response, there are no parts protruding from the
surface.Justasindummyheadtechnology,theacousticalboundary microphone
is not a „revolution“ in sound recording, but it provides an extraordinarily
detailed impression of the depth of the room with the additional possibility of
achieving striking recordings of excellent transparency with only one or two
microphones.
왘Note: Before operating the microphone the first time
remove protecting cover.

Tips for the use of the acoustical boundary microphone
Themicrophone should, if possible,bepositionedormountedonanacoustically
live backing surface such as floor, wall or ceiling. Alternately, the MKE 212 can
be mounted at the centre of a large wooden board of sufficient size or, if this
is impossible for aesthetic reasons, on a transparent acrylic glass panel, which
then is mounted on a floor stand. It can also be suspended from the ceiling. The
board should be large, as its dimensions determine the point of the microphon’s
6 dB accentuation. In the free field, that is without any additional surface, the
MKE 212 has a lower frequency roll-off point of 1 kHz. To attain a lower cut-
off frequency, e.g. 500 Hz, a board of 350 mm x 350 mm would be necessaray.
When positioned on the floor, the microphone capsule should in any case be
protected by mounting the non-crush windscreen, which ist supplied as
standard accessory. This windscreen does not have any influence on the
acoustical characteristics of the microphone.
Due to is omnidirectional characteristics, the acoustical boundary microphone
is of limited suitability for recordings in surroundings with a high level of
background noise. Its prefered application is in recording studios and other
similarly damped but good acoustical evironments.
I you want to achieve most natural recordings, place the acoustical boundary
microphone at the position in front of the instrument or the orchestra, where
you have the best aural reception.
If two acustical boundary microphones are used as a pair of microphones for
stereo recording, the minimum distance between the two microphones should,
regardless of the width of the acoustic source, be kept at approx. 1 m to obtain
a defined left-rigth perception.
The advantages of this microphone become most obvious in recordings of
acoustic (classical) instruments.
Please make sure that neither microphone or windscreen are covered with
paper, fabric, etc. as this would affect the acoustical performance of the
microphone.
The suggestions given here are confined to be basic application of the MKE 212.
We have consciously not given any finished guidelines, because from our point of
view they would not be very helpful, bearing in mind that every user has his own
ideas about the sound of an instrument an orchestra or a vocal group, not to
mention the ever differing acoustical conditions. The MKE 212 offers a multitude
of application option, which can only be revealed by practical work and
experimentation with the microphone.

Example for Use
Nominal frequency response

Technical data
Pick-up pattern hemi-spherical
Frequency response 20 - 20,000 Hz
Sensitivity free field, no load 20 mV/Pa ±2.5 dB at 1 kHz
Nominal impedance 50 Ω
Min. terminating impedance 1000 Ω
Equivalent noise level 27 dB A-weighted (DIN IEC 651)
38 dB CCIR-weighted (CCIR 468-3)
Max. sound pressure level 124 dB at 1 kHz (K=1%)
Power supply MKE 212-P: Phantom 12 - 48 Volt
MKE 212-60: from K6 / K6P
Supply current ca. 2,6 mA bei Phantomspeisung
Connector MKE 212-P: 3-pinXLRwithintegralphantompoweradaptor
MKE 212-60: Special connector for system K6
Cable length 1.5 m
Dimensions in mm 165 x 165 x 10
Weight 850 g
Pick-up pattern