royer R-121
, Operation Instructions Manual & User Manual

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found for any given microphone, and usually experimentation
reveals it. The sweet spot can be extremely variable since it
depends on the quirks of a given microphone and a given room.
Once the sweet spot is discovered, this placement can become
a “rule of thumb” starting point for future microphone place-
ment with similar sound sources. Remember this: If it sounds
good, it’s probably right. If it doesn’t, move the microphone.
It’s often more effective to reposition the microphone than to
start fiddling with knobs. Knob twisting can affect headroom
and phase coherency and add unwanted noise.
The following is a list of variables that account for “sweet
spot” effect:
1. Frequency response variations due to proximity effect.
2. Frequency response variation due to treble losses as a result
of absorption and “narrowing” of the pattern at high frequen-
cies, causing weakening of highs as the microphone is moved
away from the sound source.
3. Variation in ratio of direct to reverberant sound.
4. Tendency of a microphone to favor the nearest sound source
due to a combination of these items, plus the influence of
inverse square law. Inverse square law states that for each halv-
ing of source-to-microphone distance, the sound pressure level
quadruples .
Other Types of Microphones
For the same ratio of direct to reverberant sound, omni-direc-
tional microphones must be closer to the sound source than car-
dioid or bi-directional microphones. Microphones should gen-
erally face the sound source head-on or treble losses due to
phase cancellation can result. The exception here is for large
condenser microphones, which often give the flattest response
at an angle of about 10-20 degrees (off axis), where phase loss
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