replace in opening quotations

node157.html

@@ -82,7 +82,7 @@ using the <TT>vcf~</TT> object, introduced here:
  WIDTH="53" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
  SRC="img1022.png"
  ALT="\fbox{ \texttt{vcf\~}}">:
-<A NAME="10846"></A>a ``voltage controlled" band-pass filter,
+<A NAME="10846"></A>a "voltage controlled" band-pass filter,
 similar to <TT>bp~</TT>, but with a signal inlet to control center frequency.
 Both <TT>bp~</TT> and <TT>vcf~</TT> are one-pole resonant filters as
 developed in Section <A HREF="node143.html#sect8.twopolebandpass">8.3.4</A>; <TT>bp~</TT> outputs only
@@ -109,7 +109,7 @@ Example H04.filter.sweep.pd (Figure <A HREF="#fig08.29">8.29</A>) demonstrates u
 <TT>phasor~</TT> object (at top) creates a sawtooth wave to filter.  (This is
 not especially good practice as we are not controlling the possibility of
 foldover; a better sawtooth generator for this purpose will be developed in
-Chapter 10.)  The second <TT>phasor~</TT> object (labeled ``LFO for sweep")
+Chapter 10.)  The second <TT>phasor~</TT> object (labeled "LFO for sweep")
 controls the time-varying center frequency.  After adjusting to set the depth
 and a base center frequency (given in MIDI units), the result is converted into
 Hertz (using the <TT>tabread4~</TT> object) and passed to <TT>vcf~</TT> to set