replace in opening quotations

node53.html

@@ -107,21 +107,21 @@ Non-looping sampler.</CAPTION>
 The amplitude of the output of <TT>tabread4~</TT>  is controlled by a
 second <TT>vline~</TT> object, in order to prevent discontinuities
 in the output in case a new event is started while the previous event is still
-playing.  The ``cutoff" <TT>vline~</TT> object ramps the output down to zero
+playing.  The "cutoff" <TT>vline~</TT> object ramps the output down to zero
 (whether or not it is playing) so that, once the output is zero, the index
 of the wavetable may be changed discontinuously.
 
 <P>
-In order to start a new ``note", first, the ``cutoff" <TT>vline~</TT> object is
+In order to start a new "note", first, the "cutoff" <TT>vline~</TT> object is
 ramped to zero; then, after a delay of 5 msec (at which point <TT>vline~</TT> has reached zero) the phase is reset.  This is done with two messages: first,
 the phase is set to 1 (with no time value so that it jumps to 1 with no
-ramping).  The value ``1" specifies the first readable point of the wavetable,
+ramping).  The value "1" specifies the first readable point of the wavetable,
 since we are using 4-point interpolation.  Second, in the same message box, 
 the phase is ramped to 441,000,000 over a time period of 10,000,000 msec.  (In
 Pd, large numbers are shown using exponential notation; these two appear as
 4.41e+08 and 1e+07.)  The quotient is 44.1 (in units per millisecond) giving
 a transposition of one.  The upper <TT>vline~</TT> object (which generates the
-phase) receives these messages via the ``r phase" object above it.
+phase) receives these messages via the "r phase" object above it.
 
 <P>
 The example assumes that the wavetable is ramped smoothly to zero at either