Audio mixer setup, panning ???

[Jonathan Levin]

Hi everyone.

I am having a moment here where I seemed to have forgotten something.

Let's say I'm recording dialog from one person. My main mic will be a Lav, and my second mic for a slight room ambience will be boomed from top on stand just outside of frame.

When I've done this before, I would set up on my mixer/recorder for the main (Lav) in input 1 on mixer and I would hard pan that to the left. In input 2 the Boom (ambient) panned hard right. I adjust the trims on both to get the levels that I desire, with the boom (ambient being lower than my Lav obviously.

I'm recording Poly Wav that include the L/R mix as well as the ISO's. In post, I generally find myself using and working off the two ISO to get the mix I like.

So this is where this 'ol man is confused: If I am using just the ISO channels in the file, why am I panning either of those two inputs at all if I am just using the ISO's? I see the mix L/R as just another back up plan just in case. I know this maybe a dumb question.

I've had good luck with this set up before, but with the tracks set to no pan, the gain (volume?) of that track seems twice as loud, since I am not panning anything out.

Loosing my mind and thanks for being kind.

Jonathan

[Jay Massengill]

Which exact model of "mixer/recorder" are you using? That will make a big difference in the exact language of any explanation.

For most users, using a simple mixer connected to a simple recorder and recording simple WAV files, you pan the sources hard Left and hard Right because that's the only way to keep them separated. There isn't any function to also get a simple mix track AND keep the lav and boom tracks separated for mixing later to best suit the final result.

Do you have a more advanced multitrack recorder I suspect? Or maybe there's just confusion in the terminology about the resulting WAV files being discussed and how those tracks can be manipulated later on the timeline?

[Roger Gunkel]

As Jay says, your terminology is slightly confusing, but it sounds as though you are using a simple mixer with a stereo out. If that is the case, then both your mics need to be set to optimum levels whilst panned left and right. That will give you a separate recording of each mic on the left and right outputs, both at optimum level. A mix balance is irrelevant at the recording stage as you can adjust them in post on the timeline, to mix in the amount of ambient sound you want to the lav mic recording.

Roger

[Jonathan Levin]

Sorry guys.

I am doing this on a Sound Devices 633 mixer/recorder.

Basically I have that set up where I am recording L/R mix, as well as seperate independent channels for each of the two mics for each Poly file. Maybe I'm using the term ISO wrong.

Jonathan

[Roger Gunkel]

If you are recording tracks for each mic and a stereo mix, it sounds as though you are covering all options. Personally, I would prefer to leave the final mix for post rather than using a live mix in the field, so I can't really see the value of the live mix unless you are using more mics than individual recording tracks.

Roger

[Jonathan Levin]

Thanks Roger.

The more I think about this I think I realize why I do the panning thing. If I were to ONLY use the seperate lav and boom tracks and mix in post, I probably could record using no panning on either input on my 633. However the mix L/R would sound awful since the boom would be far to "present".

Doing the panning, setting faders on each input for a "almost close" mix, I would end up with a useable L/R mix as well as the seperate channels that I could also adjust somewhat in post.

Does this sound about right??? Seems like both methods have their advantages and disadvantages.

[Jonathan Levin]

I think in my original post I mentioned adjusting trim when I think I meant faders. Both trims I set to best level with no clipping, limiters enabled.

[Roger Gunkel]

Originally Posted by Jonathan Levin

Thanks Roger.

The more I think about this I think I realize why I do the panning thing. If I were to ONLY use the seperate lav and boom tracks and mix in post, I probably could record using no panning on either input on my 633. However the mix L/R would sound awful since the boom would be far to "present".

Doing the panning, setting faders on each input for a "almost close" mix, I would end up with a useable L/R mix as well as the seperate channels that I could also adjust somewhat in post.

Does this sound about right??? Seems like both methods have their advantages and disadvantages.

I don't really understand why you need to use a live stereo mix of the boom and lav mics at all, when you are recording both independently. Surely you can just mix the level of the boom mic in post, unless you don't want to go through the process of doing a post mix. A live mix to me, sounds like the most unreliable choice as you cannot change it afterwards.

Roger

[Jay Massengill]

If you are recording isolated tracks for the two mics and a stereo mix, your choice of panning the two sources into the stereo mix depends on what is most important to you.

It will also depend on how much independent control you have between a source going to its isolated track and how loud it is also going into the stereo track.

If you can vary the volume of a source independently between its isolated track and the stereo mix, then you could have the isolated tracks as a full volume backup, AND get a pretty good stereo mix.
This would be most advantageous in a long-form program, or any time you must have a mix completed quickly or even at the instant the recording is stopped, but with the ability to fix parts later by going back to the isolated tracks if needed.

However, if you can't vary the volume between a source's isolated track and the stereo mix you would have to decide which is more important. Having a full volume isolated track of the boom mic with too much boom in the stereo mix, or having a lower level isolated boom track and having a very good stereo mix recorded live.

So it still depends on the project, how the recording will be handled (and by who and how quickly) in post, and how much independent control you have inside your mixer/recorder's routing and level control.

Panning the two sources apart and having them both at full volume in the stereo mix just gives you a redundant copy of the isolated tracks.

Panning them both to center in the stereo track would require the boom to be at a lower level, otherwise the stereo track is no good for anything and can't be separated later.

If you can reduce the level of the boom track going into the stereo mix that could save you a lot of work later IF you get it right in the field. You could still go back to the isolated tracks and fix it, or just use the isolated tracks in post like you are doing now, as long as the lower level of the boom recording is sufficient to handle any problem.

For example, what if the lavalier mic totally fails during the subject's best response and no one at that instant is monitoring the recording to bring up the boom mic to a higher level. Would a boom mic level that is good for a two-channel mix be sufficient to boost in post as the only source in an emergency?

With a good room, a good mic, and your good SoundDevices recorder it probably would be clean enough. It would just sound more distant and less present compared to the lav.

So decide what's more important, full-volume redundancy that may never be used or saving post-production time by setting a good mix live that could still be fixed later if you hate it.

[Jonathan Levin]

Thanks Roger.

And Jay, thanks for all your thoughts. I think if I'm reading this right, I'm kind of in the same ball park as far as what I'm doing.

Things probably get much more interesting if there are more than one person who need audio recorded in a scene ;-0

Your ideas appreciated.

JL

[Roger Gunkel]

If there are more people in the scene, it depends on how many there are and how far apart they are. Every scenario is different and is dependent on many factors including room ambience and refectivity, other intrusive sound, seperatiom etc. For only 2-4 people, I just use a small voice recorder and lav on each one and mix in post. a takes away the worry of cables, wireless etc.

Roger

[Greg Miller]

What about delay? If one mic is 8" from the mouth, and the other mic is 24" from the mouth, that's a 16" difference, which equates to roughly 0.00118 seconds. Not a problem in terms of sync, but possibly in terms of phase. If the two mics are mixed at equal level, you'd get cancellation for a frequency with half-wavelength = 0.00118 seconds, or roughly 422 Hz, and harmonics thereof.

Of course if the boom mic is mixed in at a significantly lower level, the comb filtering would be reduced in amplitude.

But to take a theoretical approach, shouldn't you slide the boom track so it matches the lav track, before you do any mixing?

[Roger Gunkel]

I would think that the delay from reflections in the room to the boom mic would also be very noticeable. As a matter of course, I would always synch seperate sound recordings at the post mixing stage, although the recorder that Jonathan is using has the facility to delay a track input by a variable ammount. Trying to sort that out in a live situation would not be something I would particularly relish :-(

Roger

[Jonathan Levin]

You guys are good!

I was actually think about this today. I always have the 3 to 1 rule in my head when setting up mics, but in this case my lav is 8-10 inches from mouth and the boom is just above head out of frame, but far less than the 3 feet if following 3-1. More like 2 feet.

Again my lav falls between -5 and +8 tops on the SD 633. And the Boom somewhere around -25 to -18

Not having any problems (yet) with the quality of audio. I rely on my ears a lot, and they are still pretty good.

[Greg Miller]

Originally Posted by Roger Gunkel

I would think that the delay from reflections in the room to the boom mic would also be very noticeable. As a matter of course, I would always synch seperate sound recordings at the post mixing stage, although the recorder that Jonathan is using has the facility to delay a track input by a variable ammount. Trying to sort that out in a live situation would not be something I would particularly relish :-(

Roger

The reflections will certainly be audible, although he calls them "room ambience" ... in fact that seems to be why he's using the boom in the first place.

Reflections are, by definition, delayed. But what I'm talking about are two different versions of "direct" sound. I agree, I would not bother trying to do the calculations on location ... I'd just look at the tracks in post, and slide the boom track up to match the lav track.