The No.1 Website for Pro Audio
EQ = Negative Amplitude Loss?
Old 14th January 2022
  #1
Here for the gear
 
EQ = Negative Amplitude Loss?

Hey,

stupid me exported his mono recorded vocals in stereo...

1. This should not make a difference or cause problems at all, right?

However, after eqing the signal and bouncing it I found a somewhat strange looking data... Seems like my eq ate away some of the negative amplitude?

I then thought, okay, lemme make it a mono signal first, maybe there is some strange stuff going on. What I did next was taking only the left side of the signal LR -> LL (Stereo Shaper in FL)

I didn't see any difference between those to files at all but after overlapping the LL signal with the old one (the summed left and right view) there was no perfect overlap, now I don't know if that is thanks to the stereoshaper... It also just looks like a tiny delay, not like a phase problem, so I guess this kinda answers my first question that there is no real problem with a mono recording bounced in stereo?

Ok, then I've put the same eq on it once again (ProQ3, zero latency mode) but it still ate away the negative amplitude.

Then I thought hmm... what is going on? I then put the EQ on Linear mode and there my negative amplitude was unchanged. (Of course the maximum peak is attenuated thanks to the eq but yet it is "intact")

2. What does it mean if only the negative amplitude gets eaten away and not the right as well?

3. What is going on? Do I have to worry?

I've added a screenshot of a stacked linear phase and zero latency version, there you can cleary see the "loss" of negative amplitude... also I've uploaded the zero latency and linear phase audio.

No deesser on the vocals so be prepared :D Also, does this vocal sound compressed too much? And btw what about this stacking compressor thing, so that one compressor doesn't have to work as much... is it really worth it or just some fancy stuff that doesn't really make a change?

Thanks!
Attached Thumbnails
EQ = Negative Amplitude Loss?-original-after-eq-.jpg   EQ = Negative Amplitude Loss?-lr-ll.jpg   EQ = Negative Amplitude Loss?-ll-over-old.jpg   EQ = Negative Amplitude Loss?-ll-after-eq.jpg   EQ = Negative Amplitude Loss?-linearphase.jpg  

EQ = Negative Amplitude Loss?-zerolatency-linear-phase-stacked1.png  
Attached Files

Zerolatency.wav (853.2 KB, 185 views)

linearphase.wav (850.7 KB, 184 views)


Last edited by Stereogamy; 14th January 2022 at 09:52 PM.. Reason: Add
Old 14th January 2022
  #2
My guess would be, that a stereo bus plugin, or attenuation affected volume, that was not exported, decreasing volume. A mono track, converted to stereo, should be identical without any panning
Old 14th January 2022
  #3
Here for the gear
 
Further experimentation showed me that the lowcut causes the negative amplitude to be eaten... even at a 12db one

I do know that a lowcut causes a phaseshift yet should this be happening?

Last edited by Stereogamy; 14th January 2022 at 10:05 PM.. Reason: add
Old 14th January 2022
  #4
Lives for gear
 
Korcraft's Avatar
 
🎧 5 years
Why don't you just re-export to mono?

The stereo looks normal ...so you could eve just export the stereo to mono...You don't need to do LR>LL etc.

I'm guessing that the plugin you are using to EQ is having some stereo issues. Have you tried a different EQ plugin?

Again...if you can go back and just export the vocal as mono...do that. If for some reason you no longer have access to the original vocal that you exported...Take the stereo export...and export a mono. Pull the new mono track into the DAW...If the wave form looks weird like this without adding any EQ...then I'd say something went weird with your original stereo export.
Old 15th January 2022 | Show parent
  #5
Here for the gear
 
Quote:
Originally Posted by Korcraft ➡️
Why don't you just re-export to mono?

The stereo looks normal ...so you could eve just export the stereo to mono...You don't need to do LR>LL etc.

I'm guessing that the plugin you are using to EQ is having some stereo issues. Have you tried a different EQ plugin?

Again...if you can go back and just export the vocal as mono...do that. If for some reason you no longer have access to the original vocal that you exported...Take the stereo export...and export a mono. Pull the new mono track into the DAW...If the wave form looks weird like this without adding any EQ...then I'd say something went weird with your original stereo export.
I could re-export it to mono but that wouldn't make a difference for this test, right? It is just a testrecording, nothing serious.

When eqing it with the stock eq it does also alter the negative amplitude but not as heavy as the proq does.

Yet all this doesn't answer the question why this happens and what it means.

I can't really tell a difference between both audio files, can you?
Old 15th January 2022 | Show parent
  #6
Lives for gear
 
Korcraft's Avatar
 
🎧 5 years
Quote:
Originally Posted by Stereogamy ➡️
I could re-export it to mono but that wouldn't make a difference for this test, right? It is just a testrecording, nothing serious.

When eqing it with the stock eq it does also alter the negative amplitude but not as heavy as the proq does.

Yet all this doesn't answer the question why this happens and what it means.

I can't really tell a difference between both audio files, can you?
I thought you said you accidentally exported it as stereo. I didn't realize you did this on purpose for testing.

The point I'm trying to make is that the different might already be there from the export.

Maybe it was panned slightly left and when you add the EQ it makes this difference bigger.

When you just listen in mono to the stereo version...does it change the way the file sounds at all?

Not left to both or right to both...just collapse your master fader to mono and listen.

See if there is any change.
Old 15th January 2022 | Show parent
  #7
Here for the gear
 
Quote:
Originally Posted by Korcraft ➡️
I thought you said you accidentally exported it as stereo. I didn't realize you did this on purpose for testing.

The point I'm trying to make is that the different might already be there from the export.

Maybe it was panned slightly left and when you add the EQ it makes this difference bigger.

When you just listen in mono to the stereo version...does it change the way the file sounds at all?

Not left to both or right to both...just collapse your master fader to mono and listen.

See if there is any change.
Wasn't panned and it does not make a difference at all. It was / is just a mono signal in a stereo file.

Dunno what's going on but I also couldn't find something bad about it, just that the wav looks strange.
Old 15th January 2022 | Show parent
  #8
Lives for gear
 
Sharp11's Avatar
 
🎧 15 years
Quote:
Originally Posted by Stereogamy ➡️
Wasn't panned and it does not make a difference at all. It was / is just a mono signal in a stereo file.

Dunno what's going on but I also couldn't find something bad about it, just that the wav looks strange.
If you take a mono signal and export it as stereo, it’ll create a left and right identical copy with each 6 db down in volume. You can choose either the left or right, discard the unused copy and turn up the one you save 6db.

If the file you exported is truly a mono file, even with effects, both sides will be identical (6db lower).
Old 15th January 2022 | Show parent
  #9
Lives for gear
 
Korcraft's Avatar
 
🎧 5 years
Quote:
Originally Posted by Stereogamy ➡️
Wasn't panned and it does not make a difference at all. It was / is just a mono signal in a stereo file.

Dunno what's going on but I also couldn't find something bad about it, just that the wav looks strange.
It could just be the way your DAW is representing the wave form and there is no actual audio differences.

Still a bit strange
Old 15th January 2022 | Show parent
  #10
Here for the gear
 
Quote:
Originally Posted by Sharp11 ➡️
If you take a mono signal and export it as stereo, it’ll create a left and right identical copy with each 6 db down in volume. You can choose either the left or right, discard the unused copy and turn up the one you save 6db.

If the file you exported is truly a mono file, even with effects, both sides will be identical (6db lower).
That's what I did Yet does no1 of you guys have the same "issue" that if you lowpass (ideally with a proq3 for this test) that your negative amplitude gets eaten?
Old 15th January 2022 | Show parent
  #11
Here for the gear
 
Quote:
Originally Posted by Korcraft ➡️
It could just be the way your DAW is representing the wave form and there is no actual audio differences.

Still a bit strange
Prolly just a proq3 thing... but yea, as long as it has no negative effect... yet still interesting
📝 Reply

Similar Threads

Thread / Thread Starter Replies / Views Last Post
replies: 37134 views: 3116953
Avatar for Agreed
Agreed 51 minutes ago
replies: 469 views: 86682
Avatar for MogwaiBoy
MogwaiBoy 7th April 2022
Post Reply

Welcome to the Gearspace Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…

Forum Jump
Forum Jump