[PD] limiter~ problem

[Yury]

hi all ,

after some pretty simple calcs i have found an answer
to my problem, which was not so obvious for me earlier,
and i decided to reply to my own post to help other
novices may be..

the release time of zexy's limiter (in mode 0) is not a constant.
it depends on threshold and input signal's levels,
and is equal to time in ms from the moment the compressor
realizes that the input signal's level has changed from
one that is being compressed (A1) to one that is lower than
the threshold to the moment the output becomes 2 times (=6 dB)
higher then the A1's level.

-- 
Best regs,
 Yury                            mailto:yurolog at mail.ur.ru


Tuesday, April 20, 2004 7:01:08 PM i wrote:

Y> Hello list,

Y> i'm now  testing zexy's [limiter~] and can't get clue of one thing.

Y> according to the sound processing literature [1] the release time of a
Y> compressor/limiter is the time of response to the signal's decrease
Y> in level from one that is being compressed to one that is lower than
Y> the threshold.
Y> ok, that's fine.
Y> but when i set the threshold level in zexy's limiter to, say, 95 dB,
Y> and release time - to 300 ms and feed it an impulse,
Y> rising from 90 dB to 110 dB and back, I find out that the release time
Y> is in fact 750 ms !
Y> May be this is some feature that i'm missing ?

Y> To check it out i fed the same impulse to another
Y> limiter, taken from the WONK's site[2], with the same
Y> threshold/release parameters and got an opposite result:
Y> the release time was just about 160 ms !

Y> Where i can get a Mulder to find out the truth ?

Y> What i need to know is the definition of release time in terms of zexy's limiter.
Y> so i could predict the results of its output.
Y> you will find the test-examples in the attachment.

Y> thanks in advance !  

Y> [1] = Introduction to Sound Recording by Geoff Martin:
Y> http://nml.cult.bg/data/music%20research/audio%20engineering/Introduction%20to%20Sound%20Recording%20-%20Geoff%20Martin.zip
Y> [2] = http://wonk.epy.co.at/work.pd/limiter/limiter.tar.gz