I would like to restore some dynamics in some of my old songs which have been heavily compressed and even limited during the mastering.

I don't have the original mixes, and I know that what is gone is gone, but I still want to do some experiments using an upward expander on those files.

AFAIK, this is basically how an upward expander works: threshold determines the input level at which the expander activates. Negative ratio sets the amount of amplification of the signal that passes the threshold. Knee affects how the expander behaves with signals that are very near the threshold. Attack time is the amount of time the expander will go from zero expansion to full expansion based on the ratio and threshold settings, and release time determines how long it takes for the expander to stop expansion.

And this is the process I'm following:
1) normalize the master file to -6db to leave some space to the expander and avoid clipping;
2) using Izotope Ozone 5, set the threshold just above the average loudness of the song (e.g. -7.5db) with a "gentle" ratio (e.g. 1.5:1.0), with hard knee, slow attack and long release times.
Actually, the magic happens! Well, it does not obviously restore the original mix, but at least it gives back some dynamics to the song.

BUT there is something I can't figure out.
I tried to apply this process on many songs, and in every song the first sound clips. No matter what kind of sound is (drum, bass, guitar, etc.), no matter how I set the knee and attack/release times, no matter the ratio I use, it just clips.
And this seems to have zero sense, since the first sound of every song is under the threshold, and at that point the expander simply shouldn't do anything at all. What happens instead is something like a "turning on engine" sound during the first fractions of silence, and then a boomy clipping sound when the song starts. The trick works just fine for the rest of the song.

What am I missing?
Every help is truly appreciated.

 

Last edited: Aug 31, 2023

I would forget the Normalize until you figure this out. your upside down compressor and reversed parameters will add to the confusion on it's own. Which ozone 5 plugin did you load onto the track?

 

Last edited: Aug 31, 2023

Thanks for your reply. Just the dynamics plugin is activated, in single band mode.

 

Clipping is a natural effect of upward expansion: Increasing the gain above a certain threshold will require enough headroom to avoid clipping. Just reduce the input level of the upward expander.
DAWs usually work with higher internal resolution to allow reducing the gain of your input signal without getting too much quantization noise.

 

I know it's not really your question, but just in case you could find it interesting : I usually find multiband expansion way more effective in restauring dynamics in "mastered" tracks, than single band processors.
And in case you have access to it, Spiff (by Oeksound) is kinda of a savior for me when client brings hard squashed 2-track instrumentals to be mixed with their voice, and moreover never had the "clip at beginning" issue with it. ;-)

 

you're missing lookahead function/feature in compressor/expander, and maybe also oversampling to minimize aliasing of "richer" result material

 

This is more where I was thinking. Usually when you have a very long post like this, and then a tool not doing the "expected" behavior; it's often a misconception about something. For a clipping issue, but only at the very beginning of a processed file; you will look to attack, release settings, and lookahead parameters. And also moving the waveform to be processed back in time a measure or two.

In the o5 dynamics plugin, if you hit options button; you will see that the lookahead parameter value by default is set to 1 millisecond. The Max you can set is 10ms. I would increase the lookahead first, and if the problem still exists move the waveform back 2 measures to see if that avoids the clipping. When you have a issue like this, you also want to check your compression ratio. It can affect how quickly the compressor seems to react to the information after crossing the threshold, somewhat like a sidechained comp.

 

Last edited: Aug 31, 2023

Try using Flux Audio DCompressor (or Solera as it has DCompresser built-in). It's basically an upwards-expander, but with many more advanced features than your regular compressor/expander. It's mainly for de-compressing, but you can set the ratio to inf to de-limit as well. Just be careful with the output, and use the built-in clipper when you have inf ratio enabled!

After you've used DCompressor/Solera you can try to run the track through the de-clip module in RX 8/9/10 to rebuild some clipped peaks that certainly are present in the track.

 

Last edited: Sep 1, 2023

Btw if you can't correct the issue (you probably will, but just in case) you could always edit that small bit unprocessed onto the processed file and totally get away with it.
That's kind if always how I think