Mid-side decoding issue - Total silence from the two side tracks

[quesne]

Hello All:

I have recently been getting into the world of mid-side recording. Many of my trials have been really great, with excellent fidelity, separation and flexibility when it comes to decoding and post-processing. On my most recent attempts, however, I've hit a weird snag and I am hoping someone can give me some clues as to why.

My equipment is pretty straightforward:
- Mic Pre's = ART Dual MP (2 of them, 4 channels total)
- Side Mic = CAD M179
- Mid Mic = Spark Blue
- Interface = Zoom R16
- DAW = Reaper

My technique is as follows:
- Set up the two mics with the capsules vertically in-line, and the figure-8 pattern at 90 degrees to the cardioid.
- Record on two separate tracks (let's call them Track #1 and Track #2, with the figure-8 pattern on Track #2)
- Duplicate the signal file from Track #2 to a third track, Track #3
- Pan Track #2 to hard left
- Pan Track #3 to hard right
- Reverse the polarity of Track #3
- Mix all three of the tracks together, while keeping #2 and #3 hard-panned

The problem that has cropped up is that Tracks #2 and #3 together are producing complete silence! I assume this is because they are cancelling each other out due to the identical content and opposing polarities. But it was not happening before. Does anyone have a idea what I might be doing wrong? Please let me know if I need to provide any more detail or upload the WAV files.

 

[bouldersoundguy]

If you mute one of #2 or #3, does the sound come back? If so, can you confirm the one you hear is actually panned? It sounds to me like the two tracks aren't in fact panned.

Are you recording the figure-8 side mic to a mono track?

 

[quesne]

Thanks for the reply bouldersoundguy. Answers:

1. Yes, when I mute #2, track #3 is audible. And when I mute #3, track #2 is audible.
2. I am NOT recording the side mic (CAD M179) to a stereo track. Only mono.
3. The tracks are definitely panned (see attached image), however, I can hear both tracks coming through both of my speakers, even when I mute one or the other.

 

[bouldersoundguy]

Maybe something is summing your mix to mono before it gets to the speakers.

 

[rob aylestone]

You said you panned one left and the other right, is there any chance the routing has not done the panning? What you describe is what happens when the two side channels are panned centre. I wonder if despite the pan position, those two channels are both working in mone?

 

[quesne]

Thank you for the replies bouldersoundguy and rob aylestone. I agree with the premise of the two channels either being summed somewhere, or simply stuck in mono mode due to a setting that I'm not seeing. I hope one of these ideas pans out (no pun intended ;-)

On the face of it, I don't think the Zoom R16 is doing it....or at least I don't see how it could. When you use it as an interface (as opposed to a recorder/mixer), it just passes each channel through untouched. And I do not see anything obvious going on in the DAW. But I am going to follow the signal path meticulously, step by step to see what I can find. I will report back ASAP! (probably this evening) Thanks again for all the help

 

[bouldersoundguy]

I think Reaper has a mono button on the main bus monitor output. Make sure that's not selected.

 

[quesne]

Thanks for everyone's input and suggestions. I have still not completely solved this issue, but I did discover something which was an obvious contributing factor:

I created my track template in Reaper from a previously recorded/mixed song. In the template, I had a send from the "Vocals" group to the "Instrumental" group, with the signal side-chained to a compression plug-in to "duck" the music slightly whenever the vocals come in. Somewhere along the line, as I was recording the new song (probably when I copied and pasted a track or group), the side-chain relationship became between Track #1, and Tracks #2 and #3, with a ratio that was crazy high (no idea how that happened, but certainly my doing). Likewise, whenever Tracks #2 and #3 came up, they would compress Track #1 pretty much to zero such that the only signals getting through were Tracks #2 and #3. And when you have the two side channels up and at the same level with no mid-channel, you get silence!

Anyway, the stereo-field issue is still a problem, and I am in the process of deleting all of the FX plug-ins and combing through the settings to see what may be summing the channels to mono. I will report back ASAP as soon as I find something

 

[TalismanRich]

Did you look at the two tracks and confirm that they are indeed inverted? Simply zoom into the wave from and you'll see if things are flipped immediately. If so, then your issue has to be somewhere in your routing. Are you trying to combine the two side channels to a single channel to control the M and S balancing? Are your sends hard panned L and R?

 

[DrewPeterson7]

Thanks for everyone's input and suggestions. I have still not completely solved this issue, but I did discover something which was an obvious contributing factor:

I created my track template in Reaper from a previously recorded/mixed song. In the template, I had a send from the "Vocals" group to the "Instrumental" group, with the signal side-chained to a compression plug-in to "duck" the music slightly whenever the vocals come in. Somewhere along the line, as I was recording the new song (probably when I copied and pasted a track or group), the side-chain relationship became between Track #1, and Tracks #2 and #3, with a ratio that was crazy high (no idea how that happened, but certainly my doing). Likewise, whenever Tracks #2 and #3 came up, they would compress Track #1 pretty much to zero such that the only signals getting through were Tracks #2 and #3. And when you have the two side channels up and at the same level with no mid-channel, you get silence!

Anyway, the stereo-field issue is still a problem, and I am in the process of deleting all of the FX plug-ins and combing through the settings to see what may be summing the channels to mono. I will report back ASAP as soon as I find something

Oh that's weird. :lol:

I didn't have that sort of cancelation issue you did, when I experimented a bit with mid-side, but I didn't like it because if I moved my head back and forth in the stereo spectrum, the guitar was very "unstable" - it would change significantly depending on where your head was. I don't know if this is just normal with the technique, or if there's some sort of way on input where you're supposed to be able to split the figure 8 signal so it doesn't sum to zero out of phase. It's an interesting technique, but for me that instability made it a non-starter.

 

[Papanate]

Thanks for everyone's input and suggestions. I have still not completely solved this issue, but I did discover something which was an obvious contributing factor:

I created my track template in Reaper from a previously recorded/mixed song. In the template, I had a send from the "Vocals" group to the "Instrumental" group, with the signal side-chained to a compression plug-in to "duck" the music slightly whenever the vocals come in. Somewhere along the line, as I was recording the new song (probably when I copied and pasted a track or group), the side-chain relationship became between Track #1, and Tracks #2 and #3, with a ratio that was crazy high (no idea how that happened, but certainly my doing). Likewise, whenever Tracks #2 and #3 came up, they would compress Track #1 pretty much to zero such that the only signals getting through were Tracks #2 and #3. And when you have the two side channels up and at the same level with no mid-channel, you get silence!

You have put something that nulls out - it’s pretty simple. to iD - Mute the Tracks - Unmute them one by one - you’ll hear it right away - find out what’s inverted on the track that interferes.

Anyway, the stereo-field issue is still a problem, and I am in the process of deleting all of the FX plug-ins and combing through the settings to see what may be summing the channels to mono. I will report back ASAP as soon as I find something

You shouldn’t delete them - just turn them off.

 

[PorterhouseMusic]

Thanks for everyone's input and suggestions. I have still not completely solved this issue, but I did discover something which was an obvious contributing factor:

I created my track template in Reaper from a previously recorded/mixed song. In the template, I had a send from the "Vocals" group to the "Instrumental" group, with the signal side-chained to a compression plug-in to "duck" the music slightly whenever the vocals come in. Somewhere along the line, as I was recording the new song (probably when I copied and pasted a track or group), the side-chain relationship became between Track #1, and Tracks #2 and #3, with a ratio that was crazy high (no idea how that happened, but certainly my doing). Likewise, whenever Tracks #2 and #3 came up, they would compress Track #1 pretty much to zero such that the only signals getting through were Tracks #2 and #3. And when you have the two side channels up and at the same level with no mid-channel, you get silence!

Anyway, the stereo-field issue is still a problem, and I am in the process of deleting all of the FX plug-ins and combing through the settings to see what may be summing the channels to mono. I will report back ASAP as soon as I find something

I haven't read every word of this thread - if no one else has - and because this problem is persisting - I wanted to recommend that you start with a fresh virgin project. No template. Just raw, initial Reaper settings- and see what the results are. Apologies if I've missed something - (incredibly busy and distracted with work right now).

 

[quesne]

Did you look at the two tracks and confirm that they are indeed inverted? Simply zoom into the wave from and you'll see if things are flipped immediately. If so, then your issue has to be somewhere in your routing. Are you trying to combine the two side channels to a single channel to control the M and S balancing? Are your sends hard panned L and R?

Hi TalismanRich:

Track #3 is, indeed, phase inverted (see attached). In the case pictured, I am using the item property "Invert Phase" rather than the UI button on the track control since it provides the inverted waveform image. But either method produces the same sonic result.

I do have the mid-side tracks grouped in a hierarchy: The top level is "Instrumental", then "Mid-Side Matrix" and finally "Mid- Field and Side Field (see attached). As you can see, the pans are hard left (Track #2) and hard right (Track #3). There are no signal routings except from the "Vocal" group (not pictured) to the "Instrumental" group.

 

[quesne]

I haven't read every word of this thread - if no one else has - and because this problem is persisting - I wanted to recommend that you start with a fresh virgin project. No template. Just raw, initial Reaper settings- and see what the results are. Apologies if I've missed something - (incredibly busy and distracted with work right now).

Thank very much, PorterhouseMusic. Absolutely, I have a recording session coming up on Saturday, and I am going to start from scratch on each new project Hopefully, if I can get the mid-side matrix decoding working consistently, I will come out of that process with a sense of how to create a relatively fool-proof template

 

[quesne]

Oh that's weird. :lol:

I didn't have that sort of cancelation issue you did, when I experimented a bit with mid-side, but I didn't like it because if I moved my head back and forth in the stereo spectrum, the guitar was very "unstable" - it would change significantly depending on where your head was. I don't know if this is just normal with the technique, or if there's some sort of way on input where you're supposed to be able to split the figure 8 signal so it doesn't sum to zero out of phase. It's an interesting technique, but for me that instability made it a non-starter.

Hmmmm....I have not yet experienced that sort of sonic "instability" on my M-S recordings (at least not the ones that worked well But I must admit that I rarely listen to my mixes without headphones. I am going to go back and test a few of my good mixes on the studio monitors, and see what happens when I shift my ears relative to the speakers.

 

[PorterhouseMusic]

Thank very much, PorterhouseMusic. Absolutely, I have a recording session coming up on Saturday, and I am going to start from scratch on each new project Hopefully, if I can get the mid-side matrix decoding working consistently, I will come out of that process with a sense of how to create a relatively fool-proof template

Best of luck - I love and have used the mid-side technique quite a lot. Hope you get to a trouble free solution.

 

[bouldersoundguy]

Why not simply start with an empty project instead if rummaging through the accumulated settings of an old one?

 

[quesne]

Why not simply start with an empty project instead if rummaging through the accumulated settings of an old one?

Absolutely, bouldersoundguy. That is the plan per post #14 above

 

[PorterhouseMusic]

Any update here? I was kinda curious what the dealio was.

 

[quesne]

Any update here? I was kinda curious what the dealio was.

Hi PorterhouseMusic:

No resolution yet. I recorded a couple of songs with my daughter yesterday afternoon using M-S tracks. When I get back to the house later today, I am going to post the raw audio here. If other folks are able to decode them to produce a stereo field, then there is likely a problem with my R16 output (or possibly my headphone amp). If they cannot decode them, then I think the problem may be in my DAW settings. Thank you for following up and stay tuned!