Problems with AGC

[Svama]

Hi Vojtech,

are there any known problems with AGC.

1. question: Is this a static behaviour?
2. question: If I use a melda eq and after that a melda comp, should I use AGC on both or only in the last plugin in this channel? Until now I use it in every plugin in an channel? Is this correct?!


My problem, I get spikes at the beginning of vocal phrases! Could this an AGC problem.

Thanks and greetings

Marek

[MeldaProduction]

No no, please read the docs!!

It's a dynamic processor, which makes the output loudness equal to input loudness. For example, when you have a compressor, you will rarely wan't to do this as it will effectivelly fight the compressor! Compressor will lower the output loudness, but AGC will get it up again. With eq it makes more sense, but it's not such a good thing either, because it is dynamic - if you for example make it a bandpass, then sometimes there will be more output than in other cases, so the AGC will end up with some form of slow pumping.

The main point of AGC is to let you easily browse presets and randomize without need to adjust output gain every time. Then you can use the SET button to set the output gain permanently and afterwards you can disable the AGC. Of course, creativity has no limits .

[Svama]

OK, now I unterstand, but sad that it doesn't do what I thought, but what about a trim parameter, which would do this. I know your point. No more parameters at already existing plugins.

Next time I will read the manual.

Thanks

Marek

[MeldaProduction]

Ok Marek, but what are you asking for?

[Svama]

My question is about a real automatic gain compensation. Like auto make up gain in a compressor, also for eqs and so on. That would be outstanding.

Now after reading the manual I think using AGC in an eq should be no problem. Is that right?

[MeldaProduction]

Well, there's no such thing . Since every processing depends on input signal, there's no way to statically compensate for any change in gain. For eqs it is usually ok, but the more equalization, the more chance the output will resonate temporarily and as a result the AGC will dynamically compensate. However as I said, you can always use the Set button to make the AGC static.

In compressors we have the "Maximize" option, which is basically auto-makeup, but it definitely doesn't work as AGC, it is impossible without being dynamic. After compressor's work is to change the gain, so inverting the operation doesn't make much sense, unless you are after some creative stuff.

[elassi]

In Wavelab is (or was, I'm reading it in an old article of 2008) a feature called "intelligent bypass". It does something similar Marek's asking for. It provides a volume corrected A/B comparison upon bypassing.

Wait, there's information on youtube (at 1:49min you see the tool):

[MeldaProduction]

Well, my german isn't exactly good , but I think it's similar to AGC, except AGC is probably better as it estimates loudness, not just RMS, which I suppose is the case in Wavelab. Anyway it is not technically impossible to perform "autogain", it does not make sense in many cases, as I tried to proof here.

[elassi]

Yeah, sorry, my fault. In english it's called "smart bypass" if you want to google yourself. But guess you nailed the point already.

[MeldaProduction]

Actually I believe it's something else - imho Smart bypass is something, that bypasses the effect when it thinks it doesn't do anything. Personally I'd avoid it, especially in Wavelab.