2) The frequency response at very high frequencies can be the real one or just what the microphone
captures. If you are using a shoddy microphone, results in the high frequency range can be not
affordable. This doesn't mean that a satisfactory FIR equalization can't be done on a slightly reduced
band: just choose a max frequency value and try listening the result.
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Precision
The precision parameter, ranging from 1 to 10, is a measure of how accurate the magnitude
correction should be, with respect to the target curve. In particular, if the IR shows a deep dips in the
frequency response, using high values of the precision parameter implies that the FIR filter will totally
compensate them, with corresponding peaks in the FIR frequency response, which can result in
undesired audible ringing effects (tonal components will become visible in the time domain FIR plot).
On the contrary, using low values of the precision parameter limits the FIR to accurately compensate
only little lacks of the original IR, and to be less accurate on severe dips. This parameter should be
tried empirically and results can be checked basing on plotted curves and listening tests.
The following picture compare two magnitude plots, where the precision parameter is set to 10 (max
accuracy) in the right side graph and to 1 (min accuracy) in the left side graph. Group delay plots are
not shown since the precision parameter doesn't affect the phase compensation accuracy.
