
2000-jul-25
with synthesizer version 1.2

Bass drum
---------

2 envelopes (AENV, FENV), filter, white noise. The AENV is usually
short paced (attack, decay = milliseconds). The output of the 
AENV envelope generator is used for two purposes: To multipy the
noise with it and as excitation source for the filter. The filter
is resonant so it becomes an oscillator and the frequency of the
filter is swept down by the decay phase of the FENV (fast attack,
slow decay). To eliminate DC, the output of AENV is subtracted from
the output.


                        FENV
                         ||
                         \/
            AENV ----> FILTER
             |     |      |
             |     |      |
   NOISE ---(*)---(-)----(+)----> out

Parameters for the bass drum:

   1. attack rate for AENV    0..4095, def 1000
   2. decay rate for AENV     0..4095, def 300
   3. attack rate for FENV    0..4095, def 400
   4. decay rate for FENV     0..4095, def 100
   5. filter quality factor   0..4095, def 4093
   6. level for AENV                   def 16384
   7. level for FENV                   def 50
   8. noise level                      def 40000


Snare drum
----------

1 envelope, 1 filter, white noise. The noise goes through the envelope
and then straight to the output plus through the filter and then to the
output.


             ENV
              |
              |
   NOISE --> (*) ---> FILTER ---> 
                  |                out
                  +------------->


Parameters for the snare drum:

   1. Attack of ENV                 0-4095,   def 2000
   2. Decay of ENV                  0-4095,   def 100
   3. Filter frequency              0-131071, def 50
   4. Filter quality factor         0-4095,   def 4085
   5. Level of ENV                            def 20000
   6. Level of unfiltered branch              def 32000


Hi Hat
------

1 envelope, 1 filter, noise. The noise goes through the envelope and
the filter and is subtracted from the unfiltered signal resultig in
high pass filter.


              ENV
               |
               |
     NOISE ---(*)---> FILTER -+
                  |           |
                  +----------(-)--> out


Parameters for the hi hat

   1. Attack of ENV                 0-4095,   def 2000
   2. Decay of ENV for closed HH    0-4095,   def 10
   3. Decay of ENV for open HH      0-4095,   def 150
   4. Filter frequency              0-131071, def 30000
   5. Filter quality factor         0-4095,   def 500
   6. Level of ENV                            def 12000



 