MS micing with Figure 8?

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jabulani jonny

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Well, I haven't done much experimenting with MS micing. I've always just gone with AB, ORTF, XY and the Over the shoulder technique for guitar. I'm really interested in trying MS, but I got a little confused when thinking about using a figure 8 for the side mic.

I have a basic idea of how to set up the MS recording; three tracks with the mid mic panned center, the figure 8 on a stereo track right? At that point you're supposed to flip the phase on one side of the stereo track, but I'm not sure that you can do that in Cubase. Again, I haven't worked with it, I'm just recollecting how I normally work with it.

I did download the Voxengo MS encoder plug. Would I just insert that in my stereo track and that would do the phase-flippin-encoding for me?

And just out of curiosity...using figure 8's in general...let's say you have two vocalists singing into the opposite sides of it for BGVs, how does phase come into play there? Thx for the help!
 
You have to have the figure 8 track panned which ever way the "front" of the mic is facing, let's say right. Then make a copy of it and pan it the opposite direction, left. But now you have to invert/phase flip the opposite/left track. The Middle cardiod mic gets panned right down the middle.
 
Awesome link Benny, that provides a tremendous amount of info. Didn't go into how to use software endoders, but I can do that on my own. That really is a good link though.
 
jabulani jonny said:
Awesome link Benny, that provides a tremendous amount of info. Didn't go into how to use software endoders, but I can do that on my own. That really is a good link though.
Click to expand...

glad to help
the software matrices are just an all in one way of decoding the signal so you don't have to do it manually. You'll get the same result either way.
 
I understand that the figure 8 has the two lobes (that's what they're called?), and they are recording from opposite directions.
But I'm not clear on how decoding the m-s matrix separates the two directions.

the way i've interpreted it is that the S+ and S- signals come from the exact same source. they're just copies that are out of phase?
Is that right? :confused:
 
eraos said:
I understand that the figure 8 has the two lobes (that's what they're called?), and they are recording from opposite directions.
But I'm not clear on how decoding the m-s matrix separates the two directions.

the way i've interpreted it is that the S+ and S- signals come from the exact same source. they're just copies that are out of phase?
Is that right? :confused:
Click to expand...
The sound coming in from the two sides of the figure eight mic are opposite in phase. It's a velocity mic, so it responds to changes in air velocity, so when a sound wave comes in from one side, it pushes the ribbon "in", while the a sound wave from the other side pushes it "out." The "front" of the figure eight mic will, by convention have the same phase as the cardiod middle mic. Therefore if you put sum the two mic tracks, only the sound heard from the "front" of the side mic will be heard, because the sound from the back will be opposite phase of the cardiod middle mic and get cancelled out. Similarly, if you reverse phase on the fig8 side mic the sound coming from the "front" will now be cancelled out by the cardiod middle mic. If you pan these two sums, you'll have a stereo image. Since the cardiod middle mic is added to both sums anyway, we usually pan it dead center, even though technically you're panning one copy left and one copy right.
 
reshp1 said:
The sound coming in from the two sides of the figure eight mic are opposite in phase. It's a velocity mic, so it responds to changes in air velocity, so when a sound wave comes in from one side, it pushes the ribbon "in", while the a sound wave from the other side pushes it "out." The "front" of the figure eight mic will, by convention have the same phase as the cardiod middle mic. Therefore if you put sum the two mic tracks, only the sound heard from the "front" of the side mic will be heard, because the sound from the back will be opposite phase of the cardiod middle mic and get cancelled out. Similarly, if you reverse phase on the fig8 side mic the sound coming from the "front" will now be cancelled out by the cardiod middle mic. If you pan these two sums, you'll have a stereo image. Since the cardiod middle mic is added to both sums anyway, we usually pan it dead center, even though technically you're panning one copy left and one copy right.
Click to expand...

What you said makes sense. But I think it confused me more because I may have the wrong idea of a figure 8 mic entirely.

The figure 8 picks up sounds from two directions, right?
But don't those two directions become one single signal once it's transmitting down the cable into the preamp?
How does reversing the phase separate the two? Or does it not?
I realize it's not a stereo microphone, but I've always had the assumption that it kind of worked like one in a way.
Again, I may just have the wrong idea of a figure 8 mic. I'll look through google for a good definition.
 
eraos said:
What you said makes sense. But I think it confused me more because I may have the wrong idea of a figure 8 mic entirely.

The figure 8 picks up sounds from two directions, right?
But don't those two directions become one single signal once it's transmitting down the cable into the preamp?
How does reversing the phase separate the two? Or does it not?
I realize it's not a stereo microphone, but I've always had the assumption that it kind of worked like one in a way.
Again, I may just have the wrong idea of a figure 8 mic. I'll look through google for a good definition.
Click to expand...

Yes, the sound picked up from both sides is added (or rather subtracted) together into one signal. MS allows you to "un-add" by using a seperate mic as a phase reference. The middle mic picks up sound from both sides and adds them together, but unlike where the figure8 adds them together with OPPOSITE PHASE, the cardiod adds sound from both directions IN PHASE.

So to put it in another way....
Fig8 mic signal = Left - Right
Cardiod mic = Left + Right

So Fig8 mic+Cardiod mic = (Left-Right)+(Left+Right) = 2Left

If we flip phase of the Fig8, then we have -Fig8 = -(Left - Right) = -Left +Right

Added to the Cardiod we have -Fig8 + Cardiod = (-Left+Right)+(Left +Right) = 2 Right

If we pan these two sums to opposite directions then we "decode" the stereo information hidden in the two mic signals.
 
reshp1 said:
Yes, the sound picked up from both sides is added (or rather subtracted) together into one signal. MS allows you to "un-add" by using a seperate mic as a phase reference. The middle mic picks up sound from both sides and adds them together, but unlike where the figure8 adds them together with OPPOSITE PHASE, the cardiod adds sound from both directions IN PHASE.

So to put it in another way....
Fig8 mic signal = Left - Right
Cardiod mic = Left + Right

So Fig8 mic+Cardiod mic = (Left-Right)+(Left+Right) = 2Left

If we flip phase of the Fig8, then we have -Fig8 = -(Left - Right) = -Left +Right

Added to the Cardiod we have -Fig8 + Cardiod = (-Left+Right)+(Left +Right) = 2 Right

If we pan these two sums to opposite directions then we "decode" the stereo information hidden in the two mic signals.
Click to expand...

I guess I just need to try it out. I was planning on buying a m179 over break next month... maybe it will fully make sense to me once I give it a whirl.

Thanks for the info.
 
I think cubase has a flip phase button at the top of the mixer track. If I recall, its a little "0" with a line through it. If you have the PDF manuals, a search through them for "phase" should turn it up.

Take care.
Chris
 
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