Hi,

I think the main problem is when creating digital waveguide filters.  The
vdelay and deltapi opcodes use linear interpolation.  This becomes a problem
at high frequencies.  44.1K/5K = 8 samples which is not sufficient for
accurate tuning.  An improved version should be written which use sinc
interpolation which is commonly found in fractional digital waveguide
filters.  If someone has deep understanding of such things please write us a
fractional waveguide filter opcode.

Bye,
Hans Mikelson