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Author Topic: Replaced left channel of L/R recording w/ Right ch. - restore dynamic range?  (Read 722 times)

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Offline nassau73

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Unfortunately, a recent recording appears to have had a bad mic connection on one of the l/r stereo channels. The problem is so bad on the right channel that I had to replace the entire right channel with the left channel.

However, the sound is very flat with essentially a mono left channel.

Is there any technique that can increase the more robust concert feel / dynamic range to make this listenable?

I have both Adobe audition 3.0 and Izotope RX7 standard

Thanks for any input

Offline bombdiggity

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Unfortunately, a recent recording appears to have had a bad mic connection on one of the l/r stereo channels. The problem is so bad on the right channel that I had to replace the entire right channel with the left channel.

However, the sound is very flat with essentially a mono left channel.

Is there any technique that can increase the more robust concert feel / dynamic range to make this listenable?

I have both Adobe audition 3.0 and Izotope RX7 standard

Thanks for any input

I've seen examples of people delaying one of the channels but really don't advise that.  I usually undo that if I feel like I may listen enough for it to be worth the time doing. 

With old soundboards that have a flat house mix (also usually mono) I sometimes warm them up by very lightly applying some reverb (in AA3 : Effects > Reverb > Reverb).  There are several dimensions that can be adjusted there (as well as the final dry/wet ratio).  I tend to like things dry so am not necessarily disappointed with a mono recording to start with but they can often be gently warmed up using this (IMO).  It is a matter of adding a little dimension without introducing echo or too much tail (unless that's what you feel is missing and like that boomy back of the hall feel).  There are also some presets in it but I tweak what is now the default in mine a bit for each one.  I forget what preset I started with if I used one.  Most of them are really extreme though.  I find it is best to be fairly gentle with the effects and lean a little wetter in mixing the dry/wet balance if you want more of that feel.  YMMV. 
« Last Edit: January 11, 2019, 11:16:18 PM by bombdiggity »
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Offline EmRR

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I'd try adding early reflections to simulate some spatial room characteristics.  Probably better than reverb with decay time. 
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Offline tim in jersey

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Checking in. Have a few recordings that are otherwise pretty tits, but a drop-out, or loud-mouth drunk or loud-clapper ruins it. Never been able to master getting even getting it close to right...

I don't think dynamics is the proper way to describe it because my levels were so close, but that collapse of the STEREO image is what bugs me so much. Sounds flat, as you described.

Not sure how to fix, as best as possible, in post. 'Course this is exaggerated in 2 track recordings. I can mask this on my AUD+SBD recordings.

But when it's strictly an AUD it bugs the shit out of me, if even for a few ms... Just glad it's only ever happened a handful of times...




Offline morst

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I'd try adding early reflections to simulate some spatial room characteristics.  Probably better than reverb with decay time.
That's a very interesting suggestion. I would consider the idea of adding just a bit of stereo effect so that the final result is not pure mono, as Bombdiggity and EmRR suggest. In my mind, "early reflection" is a property of some reverb units I used during my time as a full-time rock and roll sound guy, which was 1990-1992, so consider that the digital gear was comparatively primitive.
With today's digital processing, and ESPECIALLY with the post-processing plug in effects we have available, you should be able to find some cool ideas to add just a gentle touch to open up that image a bit.
Acoustically, early reflections are extremely important for how our brains localize sounds. The "first overhead reflection" is considered the most important reflection, perhaps because it relates directly to the height of the ceiling overhead. (indoors!)
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Offline nassau73

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Thanks for the input.

Based on what has been posted here, I started playing around with the various stereo plugins in Audition. And I mean, just playing because much of the technical aspects of using these plugins is still new to me.

The plugin which accomplished the job of adding a bit of depth and adding to a more spacious stereo sound was the "Binaural Audio Panner (process)". What worked in my situation was to check "Delay Only" and set the intensity very low. Also needed to experiment with the centering values.



Unfortunately, a recent recording appears to have had a bad mic connection on one of the l/r stereo channels. The problem is so bad on the right channel that I had to replace the entire right channel with the left channel.

However, the sound is very flat with essentially a mono left channel.

Is there any technique that can increase the more robust concert feel / dynamic range to make this listenable?

I have both Adobe audition 3.0 and Izotope RX7 standard

Thanks for any input

Offline EmRR

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Forgot to mention; check in mono to make sure what gets added isn't damaging mono compatibility.  Some things do, some don't.  There's some stereo simulator plugs that make these wild zigzag patterns on a phase scope with respect to frequency, looks totally wrong but is mono compatible.   
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Recorders: Zoom F8n, Tascam DR-701D, Sony MZ-R50, portable MOTU based multitrack DAW for client work

Offline ThePiedPiper

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I use the SHEPPi Spatial Enhancer plug-in and have had WONDERFUL results when working with mono files. Just a suggestion  :guitarist:
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Offline Gutbucket

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Suggestions above are good practical advice.


I'm posting not with current practical advice but to spark discussion on a potential remedy I've wondered about for a years..

Can we measure the transfer-function relationship between channels of a specific recording configuration with the intent of using that information to create a pseudo replacement channel with at least some subset of attributes of the original when needed?   I speculate we may be able to do this before or even after a recording has been made.

Prior to the recording-
Think of digitally modeling an analog effect processor by capturing impulse responses through it.  Or modeling the reverberant behavior of a space by capturing its spatial impulse response. Instead one would need to measure the actual microphone configuration itself, likely capturing impulse responses so as to only capture the relationship between the two microphones.  One might need to capture impulses for both a direct-arrival frontal source in a pseudo anechoic environment as well as diffuse-arrival (from all directions equally) in a fully echoic environment. 

Otherwise it may work best by having stereo impulses made in the acoustic environments in which one records, through the specific microphone arrangement which one is measuring for later channel reclamation should the need arise.

For a pair of microphones, I imagine this would measure the specifics of the cross-correlations between channels for a frontal source as well as the relationship between channels for diffuse reverberant content arriving from all directions.  One could subsequently apply that to the "good channel" via convolution to mimic some traits of the missing channel with respect to the existing one.

Challenges will be figuring the need impulse measurements, making them, and applying them.


After the recording-
Whole portions of a recording already have the relationship between microphone channels encoded in them.  It should be possible to run an analysis of the complete sections of a recording in order to determine that relationship, then use that information to synthesize at least some missing channel from the good one.  High end audio analysis systems (Meyer and such) can do this in real time, with the ability to derive hall-response impulses using just live sound itself as the stimulation signal.  We don't need to do it live in real time, instead we can simply run the good portions of the recording through such an analysis and let the computer determine which stereophonic attributes of the recording do not vary over time and are specific to that particular recording.

Either way, I image this should work even better with multichannel recording configurations, where one could tap the interchannel relationships between multiple channels in recreating a single missing channel, making the system more robust.  It does require sufficient content "overlap" between channels (indeed that "overlap" is what it would recreate, rather than whatever is unique to that channel), but there is plenty of that in audience recordings.
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Offline kindms

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Checking in. Have a few recordings that are otherwise pretty tits, but a drop-out, or loud-mouth drunk or loud-clapper ruins it. Never been able to master getting even getting it close to right...

I don't think dynamics is the proper way to describe it because my levels were so close, but that collapse of the STEREO image is what bugs me so much. Sounds flat, as you described.

Not sure how to fix, as best as possible, in post. 'Course this is exaggerated in 2 track recordings. I can mask this on my AUD+SBD recordings.

But when it's strictly an AUD it bugs the shit out of me, if even for a few ms... Just glad it's only ever happened a handful of times...

depending on where it occurs etc I have had success applying a limiter to the section with loud clapper scream etc that screws with Peak value etc

doesnt eliminate them completely but can give you some headroom if thats advantageous
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Offline morst

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I'm posting not with current practical advice but to spark discussion on a potential remedy I've wondered about for a years..

Can we measure the transfer-function relationship between channels of a specific recording configuration with the intent of using that information to create a pseudo replacement channel with at least some subset of attributes of the original when needed?   I speculate we may be able to do this before or even after a recording has been made.
My, what a weird and fantastic idea!? Might have military applications.
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Offline Gutbucket

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I've been meaning to start a dedicated thread discussing that since my post above but have been too busy.  Hold tight..
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

 

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