Dual Mono to True Mono (without volume loss)

I realized today that both Ableton and Logic are incapable of bouncing a dual mono file to a true mono file without significant volume loss. I think I understand why this happens, but was surprised that I couldn’t find any software which compensates for it. Does anyone know of an app that does this properly, preferably with a batch convert option? Really appreciate any help as currently the only way is to bounce, re import, bump up the volume, and bounce again - for EVERY SAMPLE :weary:

Realized after more testing: when comparing a dual mono vs a true mono version of the same sample, there’s major volume difference in the Finder (also checked Quicktime), but when brought back into logic to compare the volume difference disappears. I tried all 3 pan laws with no change. Very strange. I realize this isn’t a RYTM specific issue, but I ran into it when prepping samples for RYTM - if there’s a better place/category I apologize and maybe it should be moved. And thank you to anyone who can help!

Just for clarification: does your “dual mono” file really contain two different independent mono signals?? Because no application does expect that and will always treat such a file as a stereo file.

Or does the file contain a normal stereo signal and the volume loss you are talking about is just caused by phase cancelation effects when adding both sides together?

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Are both mono signals identical in the first place? What’s the goal when combining them, or what’s your expected outcome?

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Thank you for the replies - @tnussb the dual mono file is a stereo file with the L+R containing the exact same audio (I double checked the wave forms are identical) so no phase cancellation. The fact that the files sound identical within Logic and Ableton, but different volumes in the finder (and in quicktime) is what’s killing me.

@Hawk - yea they’re identical. I try to have all my samples at the same level (let’s say about -1.0db), so that’s the goal. The particular goal with this sample is to create a true mono file so as to not waste space.

If some more background is helpful, I’m at a point where I’m just starting to build a sample library and want to make sure it’s done right, and that it’s well organized, efficient, and consistent.

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Maybe I’m misunderstanding but if they are identical, then why are you trying to combine them? It sounds like you already have a mono file. Just delete the left or right signal.

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This is essentially what I did in the first place (bounced from logic as a split stereo with it hard panned right, deleted the empty L file and kept the R). That’s how I made the true mono file. Still, doesn’t explain the volume discrepancy described above - I’m still uncertain of what’s causing this, which means there’s a gap in my understanding of how things are working when I’m doing sample prep. I’m a bit OCD so it’s kind of a need for me to understand something if it’s not making sense.

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Don’t pan! That’s what causes your volume loss. In Ableton you can use the utility plugin for the mono conversion. In your case with the same signal both in the L and R channel its enough to extract just one side. Almost every tool can do that “one side” extraction. What’s your OS?

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Interesting. It’s possible I did the original split conversion with the Pan law at -3db, however I have to insist this still doesn’t explain the behavior I’ve described: having two files of the same audio - one true mono, the other dual mono - that sound the same volume in logic, regardless of pan law, but different volumes in finder/quicktime.
(no panning in logic when listening to the two files here)

So maybe there is something else I’m not understanding. OSx Mojave

Volume differences during playback may be a result of the involved tools.

A simple check if the conversion hasn’t done anything to the volume is to compare the waveforms from the two files (just open them in an audio editor). When done correctly the amplitudes shouldn’t have changed a bit.

In Ableton, I would put a Utility audio fx, only one channel selected, and +3dB of gain.
Does it sound right ?

@tnussb - good idea. I tried bringing the “different volume” files back into same logic session I’m exporting from. They look and sound the same as the originals when viewed/played in logic (i.e. no volume difference between the true mono and the dual-mono), but still had the volume difference in the finder and quicktime.

BUT - then I tried turning off my audio interface (motu 8A) and suddenly - same level in finder! So, something funny about how my interface is communicating with the finder/quicktime about mono/stereo files. Very strange, just wanted to report that I resolved this issue, or at least found the culprit.

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