Gain Staging w/ Amp/Distortion emulators

Logic Pro X (and older versions) questions and troubleshooting

Gain Staging w/ Amp/Distortion emulators

Postby Electronathan » Wed Nov 18, 2009 9:18 am

I've been meaning to investigate this for some time and figure no time like the present to ask here.

When it comes to Logic's native distortion plug-ins & Amp/Pedal sims, does it make a difference to adjust the gain before going into an FX plug-in (so there are no overs going into the plug-in) OR, making the gain adjustment either internally or post FX processing? This is in regards to keeping the audio signal below 0dBFS.

Here is a scenario I'm working on right now that may make more sense to what I'm asking:
I've got a softsynth --> Pedal Board --> *Gain --> Guitar Amp Pro (clean tube amp setting to DI-Box).
Gain is to scale the audio signal so it doesn't peak above 0dBFS – But, is it essential? Ideal? No big whoop?

The point is if you're going to crank up the signal anyway for nonlinear distortion, then how necessary is gain staging in a 32 bit floating point universe?

PS: A broader discussion on gain staging is welcome if anyone wants to share their knowledge on the subject!
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Postby shivermetimbers » Wed Nov 18, 2009 12:40 pm

The bottom line is do not let a distorted (clipped) signal enter Logic from the outside world.

Inside Logic, signals act differently.

It's been discussed in other posts about Automation and signal paths.

For example, I can have a clean signal on track one. I can use plug ins and drive that signal wayyyy over the redline. I can put a meter on the last insert of my distorted channel and watch it stay in the red. Simply by lowering the output fader, the signal is no longer clipped even though it is at channel 1.
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Postby Electronathan » Wed Nov 18, 2009 2:14 pm

My approach to gain staging is primarily to keep my entire mix from clipping at the output. And, like your example states, the remedy for clipping can easily be compensated for as far as rendering an AIF. Mathematically there is plenty of headroom internally to add and ultimately subtract.

In the example where creative/deliberate distortion is the goal, is it typically the same kind of math though? Take something basic like the Gain knob on Guitar Amp Pro: Is there a neutral setting for it? (There doesn't seem to be) The numbers that distinguish the settings are arbitary yet it does both +/- gain...

Anyway, is it redundant to use the Gain plug-in to reduce the signal before hitting the G.A.P gain stage where the signal will be cranked and even cranked some more on the Master knob (and alas, taking the overall level down via the output slider on the bottom if ye so desires...)?
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Postby redlogic » Thu Nov 19, 2009 12:48 am

Logic Pro X Manual...Who?
Logic Pro 9 Manual?...WTF is that!

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Postby David Nahmani » Thu Nov 19, 2009 12:51 am

redlogic wrote:There is a very interesting and LLLooonnnggg related discussion here:

http://www.gearslutz.com/board/so-much-gear-so-little-time/420334-reason-most-itb-mixes-don-t-sound-good-analog-mixes.html


Keep in mind most of the advice in that thread is for PT which is a fixed point audio engine where gain staging is entirely different than in Logic. I wouldn't recommend that thread to Logic users for fear of getting them more confused than they need to be.
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