

2000-aug-16
with synthesizer version 1.3


REVERBENATOR
------------

   INPUT

     |
     +---------------------------------------(mix)---> OUTPUT
     |                                         |
     |                                         |
     |         .----- FILTER <----.            |
     |      +-(+)--> DELAY LINE --'--+         |
     |      |  .----- FILTER <----.  |         |
     |      +-(+)--> DELAY LINE --'--+         |
     |      |  .----- FILTER <----.  |         |
     |      +-(+)--> DELAY LINE --'--+         |
     +------+  .----- FILTER <----.  +---------+
            +-(+)--> DELAY LINE --'--+
            |  .----- FILTER <----.  |
            +-(+)--> DELAY LINE --'--+
            |  .----- FILTER <----.  |
            +-(+)--> DELAY LINE --'--+


The model for the reverbenator used in the synth is an 
array of 6 feedback loops in parallel, consisting each of 
a delay line and a first-order filter. The output of the
array, called "wet" is mixed with the original input,
called "dry".

The 9 parameters for the reverbenator are

    - the length of each delay line (in samples)
    - a half-life constant (in samples)
    - a filter pole (0..32768)
    - mix (0..16384)

The half-life constant determines how long it takes for the
reverb to decay to half the amplitude. The program takes care
of translating this to individual feedback gain factors 
accounting for the different delay lengths.

When the filter pole is in neutral position at 16384, all
frequencies have the same half-life. Below neutral, low
frequencies will live longer, above neutral, high frequencies
will live longer.

The mixture of dry and wet signal is done by the mix parameter,
ranging from 0 (totally dry) to 16384 (totally wet).

The parameters for the built-in reverb presets are

   1:  180 254 402 311 440 623  500 15000 22000
   2:  351 445 657 771 932 1153  2000 10000 20000 
   3:  1322 1493 1732 1912 1993 2051  3000 16000 18000
   4:  742 893 932 1229 1393 1598  5500 11000 16000
   5:  1393 1727 1865 1943 2175 2257  6000 16500 16000
   6:  100 103 111 117 121 129  4500 8000 20000


