rev_mono~

This reverb block contains only 1 input (the mono signal).

The creation arguments (liveness, crossover frequency, HF damping) are supplied in three inlets as shown.

• The "liveness" (actually the internal feedback percentage) should be 100 for infinite reverb, 90 for longish, and 80 for short and so on...
  
• The crossover frequency and HF damping work together: at frequencies above crossover, the feedback is diminished by the "damping" as a percentage. So zero HF damping means equal reverb time at all frequencies, and 100% damping means almost nothing above the crossover frequency gets through. This is implemented to simulate a vintage analog reverb sound, because the analog circuitry used had also as an effect that the high frequencies were attenuated.
  

version

v1.0: built 11/04/2007 with Pd v0.40-2 [pd][pdf]
Final version; defaults are included, output level has to be controlled from outside (not like in rev3~.pd)

interface

Input1: mono input channel.

Outputs1-4: 4 different combinations of the internal delay taps. Possibly combine them into left and right output

Controls:
INLET1: set a value for the internal feedback percentage, called liveness, usually between 85 and 100. It ranges form 0 to 100.
INLET2: set a value here that indicates the crossover frequency.Once reached, damping occurs. It ranges from 0 to 20kHz. Default is 3000Hz.
INLET3: set a value for percentage of feedback damping after reaching the crossover frequency. It ranges from 0 to 100.

implementation

The input directly goes to the pd doit block, actually the reverberation calculation block. In this case there is only one mono channel input. We make a combination of the same input into this block.

The control signals are, if needed, translated to different range/values and are given a name. This is the case for INLET1 (gets name fb): the liveness input goes from 0 to 100 (default 85), but in reality has a maximum value of 25%. For INLET2 (gets name lop): the crossover frequency default is set to 3000 Hz. For INLET3 (gets name damp): HF damping is set to a percentage value (default is 50) and a linear transition is set to 50 ms in order to obtain a smooth change of value.

In the figure below you can see the actual filter bank for calculating the reverberation effect. You can see there are 16 different delay lines that are combined into this diagram and all transformed with respect to the give parameters. Lop~ is used to subtract the low frequency part of the signal from the original in order to obtain the high frequency part. After this operation damping with factor damp occurs. The level of each delay tab is influenced by fb. The actual combinatorial diagram is just one implementation method. Different methods are possible. This is the best found.