[PD] PD and equal loudness: any ideas on approaching good live sound?

[Mathieu Bouchard]

On Sun, 22 Nov 2009, Dan Wilcox wrote:

> What do you guys do for your live set?  Do you do some sort of 
> EQ/compression on the final stage before going out the the dac~?

A little bit of chaos theory... suppose you apply a filter on sound, and 
you take into account the net gain of the feedback, and you call all of it 
as f(x). What can you expect f(f(x)) to be? f(f(f(x))) ? f(f(f(f(x)))) ? 
and so on. This tells you what happens with feedback.

If you have a compressor that systematically takes whatever there is and 
divides the dB by any fraction above 1 (e.g. by 1.1 such that -55 dB 
becomes -50 dB), then in «silence» it will pick up any tiny noise at the 
smallest noninfinite dB and will divide its dB by 1.1 many times until it 
becomes extremely loud. That's unstable feedback. (Stable feedback is when 
the dB of the echo is going down, but this fading out could be at any 
speed, even if it's slow.)

Therefore you can't add a plain compressor without aggravating any 
existing feedback, however tiny it is. You need to use something even more 
nonlinear than that, by adding something like a noisegate component. 
(nonlinear means anything not made by adding proportional parts).

> I found this post about the ears response to certain frequencies at 
> different sound pressure levels 
> http://gabesrocklog.blogspot.com/2009/08/eq-or-how-to-turn-down-suck-knob.html. 
> Should I try using these curves on an eq going out?

Those show you what's the gain in the ear. That doesn't tell you about the 
gain in your speakers, the gain in your amplifier, nor the gain due to 
reflection (vs absorption) on walls.

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| Mathieu Bouchard, Montréal, Québec. téléphone: +1.514.383.3801