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How to reduce background noise
• Stop the noise at its source: turn off appliances and
air conditioning; wait for airplanes to pass; close and
seal doors and windows; use a quiet room.
• Mike close with directional mics.
• Pick up electric instruments with direct boxes or
cables.
• Aim the null of the polar pattern at the offending
noise source. The null is the angle off-axis where the
mic is least sensitive. Different polar patterns have
nulls at different angles. Shown below (Figure 1) are
the null angles for various polar patterns:
Cardioid 180 degrees
Supercardioid 125 degrees
Hypercardioid 110 degrees
Bidirectional 90 degrees
How to reduce leakage
Leakage (also called bleed or spill) is the overlap of
sound from an instrument into another instrument’s
microphone. For example, if you’re miking drums and
piano each with it’s own microphone, any drum
sound picked up by the piano mic is leakage. To
reduce leakage:
• Mike close with directional microphones.
• When recording, overdub instruments one at a time
on each track of a multitrack recorder.
• Pick up electric instruments with direct boxes or
cables.
• Use a room or studio with dead acoustics. The walls,
ceiling, and floor should be covered with sound
absorbing material.
• Aim the null of the polar pattern at the undesired
sound source. For example, suppose you’re miking
two adjacent tom-toms with two hypercardioid
mics. The null of the hypercardioid is 110 degrees
off-axis. Angle each mic so that its null aims at the
adjacent tom-tom.
• Use a Differioid mic on vocals such as the Crown
CM-310A or CM-311A.
How to pick up sound at a distance
The farther you place a microphone from a sound
source, the more reverberation, leakage, and back-
ground noise you pick up. Also, you hear more mixer
noise compared to the signal because the mixer gain
must be higher with distant miking.
To clearly pick up sound at a distance:
• Use a microphone with low self-noise (say, less
than 22 dB SPL), such as the CM-200A, CM-700,
CM-150, any PCC, or any PZM® (see the Crown
Boundary Mic Application Guide).
• Boost the presence range on your mixer’s EQ
(around 5 kHz).
• If necessary, compensate for air losses at high
frequencies by boosting EQ around 15 kHz.
• Use directional microphones. You can place a
directional mic farther from its source than an
omnidirectional mic and pick up the same amount
of reverberation. The table below shows the distance
multiplier for each pattern (Figure 2):
Omnidirectional 1.0 dB
Cardioid 1.7 dB
Bidirectional 1.7 dB
Supercardioid 1.9 dB
Hypercardioid 2.0 dB
Cardioid A = 1.7
Supercardoid A = 1.9
Hypercardoid A = 2
Shotgun B = 3 to 10
depending on length
For example, if an omni mic is 1 foot from a sound
source, you can place a supercardioid mic at 1.9 feet
and pick up the same amount of reverb as the omni.
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Field:
• To reduce ambient noise, use a CM-200A cardioid
handheld mic with a foam windscreen. Roll off any
excess bass at your mixer.
• If the ambient noise level is very high and you
want to reject it, use a CM-310A handheld mic or
CM-311A headworn mic with lips touching the
grille. Roll off excess bass at your mixer.
• Clip a CM-10 miniature omni microphone to the
shirt about 8 inches under the chin. Place the foam
windscreen on the mic.
• Use a CM-312A hypercardioid headworn mic. Model
CM-312A HS mounts on a Sony MDR-7506 head-
phone.
Speeches
Speaker that Wanders,
Recording/Reinforcement:
• Clip a lavalier mic about 8 inches under the
chin.
Speaker that Stays Behind the Lectern,
Recording/Reinforcement:
• For permanent inconspicuous miking, use an LM-
type microphone on the lectern. The LM-201 has a
silent, rugged swivel mount; the LM-300A has a
quiet, economical gooseneck. The LM-300AL is 5
inches longer than the LM-300A. The LM-301A
mounts onto an Atlas flange or a mic stand.
• For temporary miking, place a CM-700 on the end of
a mic-stand boom. Position it about 8 inches from
the person speaking. Place the included foam pop
filter on the mic to prevent breath pops. Set the bass
tilt switch to roll off.
• Place a PCC-160, PCC-130, or PCC-170 surface mic
on top of the lectern, out of cavities. See the Crown
Boundary Mic Application Guide for details.
Narration recording:
• Place a CM-700 on a boom about 8 inches from the
mouth at eye height. Ask the announcer to maintain
a constant distance to the microphone.
Group discussion
Recording/Reinforcement:
• Hang a CM-30 or CM-31 straight down over the
center of the group. Group members should be no
more than 45˚ off-axis.
• Use PCC-170s, PCC-130s, or PZMs on the table. See
the Crown Boundary Mic Application Guide for more
suggestions.
Theatre, Drama, Opera,
or Musicals (Figure 17):
Recording/Reinforcement:
• Use PCC-160s on the stage floor or suspend CM-30s
or CM-31s overhead. See the Crown Boundary Mic
Application Guide for suggestions.
Film or video:
• Hide a GLM-100 or CM-10 mini mic under clothing.
• Attach a GLM-100 to the back of props close to the
action.
• In an automobile, clip a GLM-100 to the sun visor
near the center-line of the automobile.
• To reduce clothing noise when the GLM is used on
an actor, spray clothing with Static Guard® or water
(spray leather with silicone spray or WD-40®). Tape
the cable to clothing, using band-aids on skin. Make
a loop in the cable to act as a strain relief. Place the
connector near the actor’s foot for unplugging
between takes.
• For video documentaries, see the tips on news and
sports reporting and narration recording.
• For audience miking, use two PZMs 3 feet apart on
the stage front, or place two CM-700s over the
audience front row, aiming at the back row.
• For more tips, see the Crown Microphone Application
Guide for Video.
• To convert the GLM for wireless use, please order
Technical Bulletin #3.
We hope this application guide has provided some
insight into the operation and use of Crown micro-
phones. For application notes on PZMs, PCCs, SASS,
and boundaries, order the Crown Boundary Mic
Application Guide - free from Crown. For more
information, contact the Technical Support Group at
Crown International, 1718 West Mishawaka Road, P.O.
Box 1000, Elkhart, IN 46515 or phone (219) 294-8200 or
visit us on the world wide web at www.crownaudio.com.
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