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Author Topic: Recording Lead Vox with Stereo Mics  (Read 14776 times)

David Satz

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Re: Recording Lead Vox with Stereo Mics
« Reply #15 on: February 13, 2011, 08:10:15 PM »

Eric, I'm not sure that I understand exactly what you did or didn't do, but the problem with simply mixing the signal from a side-facing figure-8 into a forward-facing mike signal of any kind is that the front and back (or in your case, left and right) halves of the figure-8 pattern are in opposite polarity to one another.

If you turn a figure-8 to face sideways and you mix its output with the output from the other capsule (which is facing front), you are doing exactly what an M/S matrix does in order to obtain its left stereo channel: L = M + S.

Thus if you directly mixed a leftward-facing figure-8 with a hypercardioid, as I think you may be saying you did, you were basically steering the resulting overall (mono) pickup toward the left. The positive part of the figure-8 tends to reinforce the hypercardioid's pickup to the left of center, while tending to cancel out the part of the hypercardioid's pickup pattern that is to the right side of center.

(Please disregard the above if I misunderstood what you wrote.)

--best regards
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Eric H.

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Re: Recording Lead Vox with Stereo Mics
« Reply #16 on: February 14, 2011, 09:08:50 AM »

David,
I'm sorry I explained myself badly. What I did was an MS, with an hypercardio as the M, because the reader was not very close.
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eric harizanos

ttown

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Re: Recording Lead Vox with Stereo Mics
« Reply #17 on: February 14, 2011, 05:54:11 PM »

David Satz wrote on Sun, 13 February 2011 19:10


If you turn a figure-8 to face sideways and you mix its output with the output from the other capsule (which is facing front), you are doing exactly what an M/S matrix does in order to obtain its left stereo channel: L = M + S.

Thus if you directly mixed a leftward-facing figure-8 with a hypercardioid, as I think you may be saying you did, you were basically steering the resulting overall (mono) pickup toward the left. The positive part of the figure-8 tends to reinforce the hypercardioid's pickup to the left of center, while tending to cancel out the part of the hypercardioid's pickup pattern that is to the right side of center.



OK now I'm officially confused (not that hard to do for me!).  If I wanted to do an M/S type recording without an M/S matrix, and I had two mics at my disposal, say a ribbon mic and a cardioid pattern mic, say U87, how would I accomplish this at the board?

David, are you saying that the proper way to do this is to orient the ribbon mic sideways and pan it hard left, and then pan the U87 in cardioid pattern hard right?  I totally get what you are saying about phase canceling issues if you have any of the figure 8 capsule in the cardioid's channel... so I guess this would be the only way of avoiding this at the board?

What I have been doing lately is to use the (-) side of two ribbons and invert the phase of both, and to then pan these hard right and left.  I then use a Neumann KM-254 down the center.  It sounds great on acoustic guitar - you get the 'shimmery' factor from the KM-254 and the smoothness from the ribbons (especially beautiful are the Royer R-121s, but I've also had good luck with AEA R92 for close-micing and AEA R84 for more distant micing).

But maybe I could get better results with a modified technique?

-Terrence Town
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David Satz

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Re: Recording Lead Vox with Stereo Mics
« Reply #18 on: February 14, 2011, 10:41:20 PM »

Terrence, it is rather difficult to matrix an M/S recording on a conventional mixing desk. You would have to split the outputs of both the M channel (forward-facing) and S channel (side-facing figure-8) microphones, and invert the polarity of one of the split signals from the S channel. Then you would need to mix the M signal with the non-inverted S signal to produce stereo left, and the M signal with the inverted S signal to produce stereo right.

It can be done with some difficulty, but the gains applied to the two splits from each microphone's signal must be very precisely matched (i.e. the M gain doesn't have to equal the S gain, but once you've split M, both of its halves must receive equal gain with each other and once you've split S and inverted one branch, both of its halves must also receive equal gain with each other).

All in all, I think it is more straightforward and reliable to use a dedicated M/S matrix for this function than a mixer.

You definitely have to orient the S (figure-8) mike sideways, but it's not a matter of panning. In fact the object is to mix the figure-8 with the cardioid--but then the sum is one of the two stereo output channels. The other stereo output channel is obtained by summing the same two mike signals in the same proportion with the figure-8's signal inverted in polarity. M + S = L, and M - S = R.

--best regards
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MagnetoSound

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Re: Recording Lead Vox with Stereo Mics
« Reply #19 on: February 15, 2011, 03:39:54 AM »

David Satz wrote on Tue, 15 February 2011 03:41

Terrence, it is rather difficult to matrix an M/S recording on a conventional mixing desk. You would have to split the outputs of both the M channel (forward-facing) and S channel (side-facing figure-8) microphones, and invert the polarity of one of the split signals from the S channel. Then you would need to mix the M signal with the non-inverted S signal to produce stereo left, and the M signal with the inverted S signal to produce stereo right.




David, why does the M signal need to be split?

If you split the S signal into L and R, and invert R, you can just pan M up the centre.

Blend is simply a matter of balancing the two S channels with the M channel, and each other. Why make it more complicated than it is?


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Geoff Emerick de Fake

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Re: Recording Lead Vox with Stereo Mics
« Reply #20 on: February 16, 2011, 01:59:31 PM »

ttown wrote on Mon, 14 February 2011 16:54

 If I wanted to do an M/S type recording without an M/S matrix, and I had two mics at my disposal, say a ribbon mic and a cardioid pattern mic, say U87, how would I accomplish this at the board?
Another option is to directly record each mic to a track, and do the matrixing later at playback time. You wouldn't have the possibility to monitor during tracking, though.
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David Satz

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Re: Recording Lead Vox with Stereo Mics
« Reply #21 on: February 16, 2011, 08:47:03 PM »

MagnetoSound ("M/S"?), point well taken. Panning the M-channel microphone to center would be equivalent to an equal, two-way split.
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Schallfeldnebel

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Re: Recording Lead Vox with Stereo Mics
« Reply #22 on: February 17, 2011, 09:54:31 AM »

"Another option is to directly record each mic to a track, and do the matrixing later at playback time. You wouldn't have the possibility to monitor during tracking, though."

Some mixers and preamps actually do. Audio Developments as an example has units with M/S splits pure for monitoring. These mixers and pre's are common among moviesound recordists.

SFN
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Eric H.

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Re: Recording Lead Vox with Stereo Mics
« Reply #23 on: February 20, 2011, 06:17:51 PM »

Other brands that have MS decoder monitoring and that i use are nagra, sonosax, sound device, seemix.
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eric harizanos

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