[ardour-users] TAP Dynamics question - not directly ardour related

Josh Karnes jkarnes1 at austin.rr.com
Sat Jun 19 21:12:04 PDT 2004

Tom Szilagyi wrote:

> On Fri, Jun 18, 2004 at 10:26:06AM -0500, Josh Karnes wrote:
>>Working on developing some new functions for TAP Dynamics to do optical 
>>compression emulation, [...]
> That would be really great :)

OK well I have made some real progress on this, and I have about 72 experimental
functions defined now, so the next move is to audition all of them and figure
out which sound good and why.

In addition I may try some stuff with two-stage envelopes....  For starters I'll 
just put two instances of TAP Dynamics in a row with staggered envelope settings.

> Have a lot of fun with it. :)
> And if you have any usable functions, please send them so my plugin
> may as well evolve.

Well, since the compression ratio is not adjustable, it is unlikely I'll have a
small number of useful functions...  you know for each compression ratio, I have 
to have  a different function def.

The way I am developing these curves is using a spreadsheet and 13-20 data 
points for each one to make a complex curve (sort of "S" shaped), using math 
functions to calc the knee and what I call "reverse knee".  The math is simple, 
but changing the compression ratio changes all of the numbers since the "knees" 
are calculated based on the ratio.

There is also a variable "width"...  idea is that an optical compressor can only 
compress a particular midrange of dynamics.  If the threshold is -6dB for 
example, then it can compress from -6dB up to maybe +3dB within the defined 
ratio (roughly) but above that it no longer compresses.  So you end up with a 
curve that looks like this:

                    * * * *

The number of dB between the threshold and the "reverse knee" I am calling 

Eventually a plugin to do this would have adjustable "width", "threshold", and I 
like your input and make-up gain ideas, as well as adjustable compression ratio, 
and I still have to audition to find out the best-sounding "knee" curves.

I'll keep you posted.

Josh Karnes


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