#### Zita-Rev1 Delay-Line Filters

In`zita-rev1`, the damping filter for each delay line consists of a low-shelf filter [449],

^{4.19}in series with a unique first-order lowpass filter that sets the high-frequency to be half that of the middle-band at a particular frequency (specified as ``HF Damping'' in the GUI). Since the filter is constrained to be a lowpass, for ,

*i.e.*, the decay time gets shorter at higher frequencies.

Viewing the resulting damping filter as a three-band filter bank (§3.7.5), let and denote the desired band gains at dc and ``middle frequencies'', respectively.

^{4.20}Then the low shelf may be set for a desired dc-gain of , and its input (or output) signal multiplied by to obtain the resulting filter

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Multiband Delay-Filter Design