Crown DriveCore I-Tech 4x3500 HD Operation Manual page 37

I-Tech HD DriveCore Series Power Amplifiers
7 Advanced Operation
7.7.10 Crossover Filters
The Crossover section lets you use infinite impulse response (IIR) or
finite impulse response (FIR) filters for the crossover.
FiR advantages: FIR has a longer processing latency but has less
phase artifacts compared to IIR. FIR allows for brickwall, 48dB/oct and
24dB/octave filters with zero phase shift.
iiR advantages: FIR has one processing block per channel; IIR has one
or more. For example, you can place an FIR at only one end of a channel,
but you can place an IIR at either end.
Operation Manual
The amplifier contains four FIR blocks which can be used in various
configurations:
In Duplicate mode the same settings are used on both channels, allowing
two FIR filters per bandpass. In Unique mode the FIR filters are limited to
one per bandpass. However, if the High Pass of Channel 1 and Low Pass
for Channel 2 are set to identical slopes and frequencies, you can use FIR
on all the bandpasses. The logic for this operation is built into the software
controls. In addition, the Processing (FIR) latency sets the minimum
frequency that can be set for an FIR.
A polarity inverter button lets you change the polarity of each channel
independently.
Each audio channel has three separate places where filters can be placed in the
system: input EQ (16 filters), Crossover, and Output EQ. Up to 24 filters per
channel are available, plus crossover filters and 4 filters for the signal
generator. Each filter has up to +/-24dB of gain. The following filters are
available:
• Lowpass: Bessel 2-4, Butterworth1-4, and Linkwitz-Riley 8
• Highpass: Bessel 2-4, Butterworth1-4, and Linkwitz-Riley 8
• Lowshelf: Low-frequency shelving EQ
• Highshelf: High-frequency shelving EQ
• Lowpass EQ: Variable bandwidth, can be expressed as Q (0.100 to 35) or
Octaves (0.041 to 6.672)
• Highpass EQ: Variable Q from 0.1 to 25
• Parametric EQ: Variable Q form 0.1 to 35
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