Crossover Comparison Chart - BSS Audio FDS366T OMNIDRIVE User Manual

Crossover Shapes and Frequencies
Crossover
comparison chart
Key:
•
= Worst
••••••
= Best
BUT = Butterworth
BES = Bessel
L-R = Linkwitz-Riley
NTM = Neville Thiele
Method
Below is a chart comparing the different crossover filter types that are
provided in the FDS-366T Omnidrive. This table should help to ascertain the
particular choice of filter dependant on application. Shapes marked with an
asterisk * will require polarity inversion.
Amplitude response flatness: also known as 'frequency response', a measure of
the flatness of the amplitude with differing frequencies. Choosing a crossover
alignment that sums to a flat amplitude response is usually desirable because
such a system will require less equalisation.
Group delay flatness: a measure of how different frequencies are delayed
throughout the crossover region. Although it is unlikely that all frequencies
can be delayed equally, a smooth group delay response that lacks peakiness is
desirable.
Polar response: a qualification of the lobing effect due to the distance between
any pair of drivers involved in the crossover. The main lobe needs to be on-
axis so that listeners on-axis do not hear dips in the amplitude response
through the crossover region.
Roll-off rate: A measure of how quickly the slope of the filter drops off to a
much lower amplitude. A steeper slope is generally required to maximise the
potential of driver frequency response and to narrow the frequency range that
is affected by the crossover operation.
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FDS-366T