Logic Pro 9 Urgent: Problem with Merge Regions Command

#1
When merging regions with key command, the gain is increased and clipped. This has never happened to me before. I'm in the middle of a project. What the hell are you doing to me Logic? Anyone know if there is a new setting which controls this behavior? Bouncing regions in place and even doing a standard offline bounce is doing the same thing. This is some serious crap!
 
#2
is your master fader at a different level from your stereo output fader?

load up a fresh session.. drag two audio files in and merge them.. does it do the gain increase in this new fresh session?

L
 
#4
Yep, they are at Unity. Nothing is set incorrectly there. Right after my post, I did the test you suggested but ended up with the same result. This is very disturbing to me. I read a question on the Apple Logic Express forum complaining of the same phenomenon. No one had replied to it and Apple had eventually locked and archived the thread. Nice one.
 
#6
Someone on the Apple forum just made this suggestion:

Maybe you have the Gain setting up on one of the regions? Look in the Inspector to check.
I'll check the setting when I get home tonight. It seems like the most likely scenario.
 
#8
Yes. My question is really related to Logic. I don't have any system problems. I'm pretty certain the region gain setting is the reason my tracks are clipping during the bounce. It makes the most sense. I'll confirm this theory tonight.
 

Markdvc

Administrator
Staff member
#9
Yes. My question is really related to Logic. I don't have any system problems.
Even if that is the case, it is never a mistake to post your system details whenever asking for help or posting about a problem. It is very unusual to be asked not to provide too much information ;)



I'm pretty certain the region gain setting is the reason my tracks are clipping during the bounce. It makes the most sense. I'll confirm this theory tonight.
Please let us know how it works out.

kind regards

Mark
 
#10
SOLVED

The solution came through very quickly in Apple's Logic Pro forum. Here are my final remarks and a link to the thread. The cause was increased region gain settings on regions containing waveforms that were already near the digital max. There's no discernible impact prior to rendering since they extend into the headroom of 32-bit float and are brought back under control once they go through the FX chain and fader's reduced volume setting. But when these are turned off, the fader brought to unity and the track is rendered, that headroom is lost and the distortion can be heard and seen.

Eriksimon, thanks so much for your quick proposal. That was definitely the source. It's an embarrassing oversight but proof that even an old Logic sea dog like me can be fooled into thinking a sea cow is a mermaid.

Bee Jay brings up an interesting point. I don't hear distortion in the mix prior to any sort of rendering because of the 32-bit floating point headroom phenomenon. By the time the signal reaches the end of the fader, everything is under control and no distortion is heard.

This was at least a good refresher in digital signal flow and gain staging. Thanks to everyone for their help here. It was swift. I can get back to work, so many thanks.
http://bit.ly/aBEN95
 
#12
You bet. Now I'm happy for my mistake because it lead me to a much better understanding of 32-bit float. If you haven't already, it's worth reading more in that linked thread for more specifics.
 
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