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Zita-Rev1 Damping Filters

FDN reverberators employ a damping filter for each delay line

Zita-Rev1 three-band damping filter:

$\displaystyle H_d(z)=H_l(z)H_h(z)
$

where

\begin{eqnarray*}
H_l(z) &=& g_m + (g_0-g_m)\frac{1-p_l}{2}\frac{1+z^{-1}}{1-p_lz^{-1}}
\;=\;\mbox{\emph{low-shelf}}\\ [5pt]
H_h(z) &=& \frac{1-p_h}{1-p_hz^{-1}} \;=\;\mbox{\emph{low-pass}}
\end{eqnarray*}

\begin{eqnarray*}
g_0 &=& \mbox{Desired gain at dc}\\ [5pt]
g_m &=& \mbox{Desired gain across \lq\lq middle frequencies''}\\ [5pt]
p_l &=& \mbox{Low-shelf pole controlling low-to-mid crossover:}\\
&\;\mathrel{\stackrel{\mathrm{\Delta}}{=}}\;& \frac{1-\pi f_1T}{1+\pi f_1T}\\ [5pt]
p_h &=& \mbox{Low-pass pole controlling high-frequency damping:}\\
&& \mbox{Gives \emph{half} middle-band $t_{60}$\ at start of \lq\lq high'' band}
\end{eqnarray*}


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Download Reverb.pdf
Download Reverb_2up.pdf
Download Reverb_4up.pdf

``Artificial Reverberation and Spatialization'', by Julius O. Smith III, (From Lecture Overheads, Music 420).
Copyright © 2014-03-24 by Julius O. Smith III
Center for Computer Research in Music and Acoustics (CCRMA),   Stanford University
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