Common Microphone Technology and Setups
- (ideally) even frequency response and sensitivity at
- Highest sensitivity at 0 and 180 degrees, with maximum
drop at 90/270 degrees.
- Highest sensitivity at 0 degrees, and (ideally) no sensitivity
at 180, with a linear to exponential transition between both.
- Same as cardoid, with a steeper (log) sensitivity curve -
i.e. less sensitivity off-angle.
With real-world directional mics the frequency response is not linear
across the directional pattern, especially on more affordable mics - you
get what you pay for. And large distance recording with directional
microphones is more problematic as they have a proximity effect - i.e.
distance relative low frequency response.
- Individual pickup
- One suitable mono microphone per source. Nearly every
professional stage and studio recording is done that way. No stereo
ambience at all, staging (if any) done by panning in the mixdown (and
eventual reverb processing). Perfect signal for postprocessing and
optimum intellegibility, but no real stereo recording. Whenever you do
not care about ambience and have the option to install the right
microphone on every source, use individual microphones!
- A-B (narrow base)
- omni mics at narrow (20-100, typically 50 cm)
distance. Stereo image mainly due to time difference between mics.
Simple setup, but frequency-dependent obliteration of signals in mono
mixdown (poor mono compatibility) and rather limited stereo imaging over
spreakers. Good large distance properties. Headphone playback generally
better than over speakers.
- A-B (wide base)
- omni mics at wide distance. Stereo image is due to
intensity difference and large time difference. Good stereo image for
ideal speaker playback environments, but unnatural stereo imaging in
less-than-perfect playback settings, and extremely artificial over
headphones. Often has decent mono compatibility, but may fail especially
in rooms with little or no ambience.
- directional mics at the same location, at cross angles. Intensity
stereophonics. Good speaker playback and mono compatibility in a small
setup. Does better than wide A-B over headphones. Popular system for
cheap single-point mics.
- figure-eight at 180 degrees with cardoid at 0 degrees. Intensity
based, effectively an electrically generated X-Y with angle variable by
mixing. Decays to the cardioid signal on mono (perfect mono
compatibility). Somewhat lacking base width for good headphone
listening. Popular system for higher-priced single-point mics.
- Omnidirectional capsules at ear distance, separated by
(natural or artificial) head. Mainly run-time stereo imaging, with
almost natural frequency related intensity due to boundary effects and
baffling of the head. Can have perfect headphone quality, but frequency
dependent phase obliteration can make it almost useless for broadcast
(mono compatibility) and speaker playback.
- Crossed figure-eights, effectively a special X-Y setting with
rear-sensitivity. Better separation, but possible frequency obliteration
problems with in-phase sound from the rear.
- cardioids at 90 degrees separated by 20 resp. 30 cm. In between
X-Y and narrow A-B, somewhat less head-related than ORTF.
- Cardioids at 110 degrees separated by 17 cm. In between X-Y and
narrow A-B. Stereo image has sufficient amounts of intensity difference
for speaker playback, but still some runtime imaging and suitable mic
distance for natural headphone listening. Very good allround setup, but
may have some sensitivity gap in the center.
- Narrow A-B at about 20 cm with a "Jecklin disc" baffle. The baffle
provides for more intensity separation and more head-like time
difference properties. Good both over speakers and headphones, bulky
- Pressure Zone Microphones (PZM)
- Basically, an omnidirectional mic
mounted on a large flat surface. Utilizes the (usually unwanted) fact
that levels increase at surfaces. Properties extremely dependent on the
setting, but occasionally handy in wide A-B, as distance to the sound
source may have little impact on intensity (given sufficiently hard
surfaces). Most common application: Studio round-table.
The "tie-clip" binaurals are really Lavalier-type omnidirectionals and
could be used for A-B, OSS, binaural, PZM and individual pickup
technologies. The common shoulder-mount setup really is something in
between narrow A-B and binaural. For better binaural setups they should
be mounted immediately at the ears. There are some cardioid clip-ons
about, and shoulder-mounting them ought to result in something close to
DIN/NOS/ORTF - haven't tried them yet, but I'd expect them to have more
reasonable speaker playback characteristics.
Generally, intensity stereophonic recordings can be mixed and edited,
while stereo based on time difference requires absolutely identical
settings and environments between recordings for mixing/editing.
For broadcast applications, I'd recommend individual (handheld) cardioid
or pin-on microphones whereever possible, especially for interviews. If
you do not explicitly want a seasick audience, never use handheld stereo
mics, except possibly for brief ambience recordings, taking special care
not to move. For all other stereo recordings, use a mic stand, with a
M-S single-point for fast recordings. ORTF setups are better if a more
complicated fixed installation at close to medium distance is possible.
For large distances to the source, use narrow A-B or OSS.