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User’s Manual
BLM6000
Boundary Layer Mount
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USER’S MANUAL
Boundary Layer Mount
BLM6000
The BLM6000 is an accessory that will extend the use of
TM
d:screet
your
4061, 4062, and 4063.
By placing a microphone close to a reflective boundary, you
will benefit from the special characteristics of the sound
field found here: a 6 dB gain of direct sound and only 3 dB
gain of the diffuse sound. This means that the sound picked
up has both greater clarity and intelligibility compared to the
sound picked up in "free air".
Mounting the microphone
It is very important to mount the microphone
correctly! If not the sound may suffer from coloura-
tion.
The smoothest frequency response is achieved with the dia-
phragm perpendicular to the reflecting boundary. In order
to identify the position of the membrane you may have to
temporarily remove the microphone grid (see picture).
When you mount the microphone in the BLM, be sure that
the mesh is completely hidden, so there are no openings, as
they will affect the sound.
Miniature Microphones i.e. d:screetTM 4060,
d:screetTMBLM6000
TM
d:screet
BLM6000, rear view
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Please note: The microphones must be mounted
with the short grid (soft boost grid). The long grid
will not fit into the disc.
Using the d:screetTM Boundary Layer Mount
When mounted in the BLM6000 you can put the micro-
phone on all surfaces that reflect sound i.e. tables, lecterns,
etc. Even floors, walls and ceilings are very effective as
boundaries when the BLM6000 is attached to it.
In general
The pressure zone principle will be more prominent in a
larger frequency range, the larger the surface the BLM6000
is placed on. Conversely, you can experiment with a place-
ment close to the edges of a table, to the edge of the stage
floor or lectern in order to obt ain bass roll off.
If you want to place the disc on a ceiling or a wall, simply use
double-sided tape.
Please find some graphs that illustrate the frequency
response of the microphone mounted in the BLM6000.
Mounting the microphone
d:screetTM BLM6000 on floor
20
15
10
Sens.
-5
20
-15
-20
d:screet
floor re same microphone measured
in free field position
Frequency response
5
0
250 500 1K 2K 5K 10K 20K
TM
4060 in BLM6000 measured on
Freq.
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TM
BLM6000 mounted on piano lid
d:screet
d:screetTMBLM6000 on desk
20
15
10
Sens.
-5
20
-15
-20
Typical low frequence response of d:screet
d:screet
Frequency response
5
0
Infinite boundary area
Larger boundary area
Limited boundary area
20 31,5 63 125 250
TM
BLM6000 in relation to the boundary area
Smaller boundary area
TM
4060 in
Physical dimensions:
Diameter: 75 mm (3 in.)
Height: 6 mm (0.2 in.)
Weight (w/o mic): 12 grams (0.4 oz)
Order numbers:
BLM6000-B, Black
Note: Tape not included. Take care to select
tape that will not damage the surface it is placed
on.
Freq.
500
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DPA Microphones A/S
Gydevang 42-44
DK-3450 Alleroed, Denmark
Tel: +45 4814 2828
Fax: +45 4814 2700
info@dpamicrophones.com
www.dpamicrophones.com
DPI-BLM6000
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