Selection Of A Measurement Microphone; Mono Or Stereo Measurement - PROEL AXIOM - VERSION 2.0 Manual

B.5. SELECTION OF A MEASUREMENT MICROPHONE
Figure B.4: Measurement microphones position: (a) on microphone boom stand, (b) in ground-plane.
to the use intended for the results of the measurement. For time alignment of the Subs, it is necessary
to position the microphone in the ground plane.
B.5 Selection of a measurement microphone
When using an RTA or a transfer function measurement instrument, it is of paramount importance that
the measurement microphone has a linear response. It is therefore necessary to test at a sound pressure
level at which the response of the microphone remains linear; otherwise the resulting data from your
measurements will be the sum of the responses of the system under test and those of the microphone
itself. This will obviously result in tremendous errors
There are many measurement microphones on the market with very low costs, but with unknown
characteristics. The problems caused by the use of a microphone with unknown characteristics greatly
outweigh the cost of a reliable measurement microphone.
B.6 Mono or Stereo Measurement?
Typically concert sound systems are stereo with one array per channel. How should one of these be
measured in order to be correctly aligned and equalized? This is not an easy question to answer and
should be evaluated case by case, however there are some general rules which can be applied to
provide reliable results.
For the alignment you should proceed one channel at a time. It can be assumed that the Left and
Right channels are perfectly symmetrical, and once one channel is set up it is sufficient to simply copy
the delay times in the processor from one side to the other. As for the equalization, the measurement
and adjustment can be applied to one channel at a time or directly to the system in stereo. In the second
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Equalizing the measurement microphone response together with the system.
B. Notes on system measurement
(a)
(b)
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