[PD] compander-limiter from slop~-help.pd

[Tom Erbe]

here’s a basic compressor patch i made for class. you really want separate attack and decay controls (slow the attack to let initial transients through uncompressed, slow the decay to minimize pumping). also, varying the [env~] window can change the responsiveness.

a high threshold, high ratio, and pretty fast attack/decay is needed for limiting.



a good overview article with ideas for further compressor abstractions - 

https://www.soundonsound.com/techniques/using-your-daws-compressors-limiters

> On May 3, 2021, at 8:08 AM, Miller Puckette via Pd-list <pd-list at lists.iem.at> wrote:
> 
> Ahhh, you noticed that "warm tube-compander" sound - producers pay top $ for
> that :)
> 
> I think it's pretty easy to get lower distortion by making the response curve
> exactly flat below maximum amplitude - I didn't do that in this application
> thinking that the limiting is going to kick in often and so there will
> often be distortion anyway... anyone who hits, say, 0.7 with any frequency is
> also going to hit 0 sometimes, and that will be the loudest sound where the
> distortion is also most noticeable.
> 
> It's possible to add a "blanking" interval like some analog solid-state
> limiters did.  In digital, if you add "lookahead" (also known as "delay")
> you can do much, much better without having to think too hard (that's what
> Ableton's built-in compressor does; it won't do zero-delay at all).
> 
> For live applications I prefer to make them zero-delay, preferring some
> inevitable distortion to adding delay.
> 
> all part of the Dark Art (tm:)
> 
> Miller
> 
> On Mon, May 03, 2021 at 09:14:42AM +0200, Peter P. wrote:
>> * Miller Puckette via Pd-list <pd-list at lists.iem.at> [2021-04-24 17:45]:
>>> As far as I can tell limiter design is a dark art.  Here's one (that imposes
>>> a hard limit just within the (-1, 1) range - I made this for "music101" where
>>> I needed a hard limit and am assuming the input signal is a voice (so unlikely
>>> to have extremely fast attacks)...
>> 
>> Thanks Miller, 
>> it seems that this implementation causes harmonic distortion to a (200Hz
>> in my case) sine wave scaled to less than 0dBFS [*~ 0.9].
>> 
>> best, P
>> 
>> 
>> 
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> 
> 
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----
tom erbe - tre at soundhack.com
professor - uc san diego | founder - soundhack






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