Stupid M/S question...

[jnorman]

i know i have read something about this before, but could not find it with search function. is it possible to acheive an MS (mid-side) type recording using 3 cardioids? or is the exact phase reversal from a real fig 8 capsule essential? thanks.

[zoom]

in principle you can emulate a fig8 by using 2 cardioid capsules and put them as close as possible back to back together and turn the phase of the capsule pointing to the right (in an M/S setup) about 180deg. compared to the other signal. without turning the phase you will get an omni characteristics, adding the signals of both mics.
the 3rd cardiod should be the mic for the M-channel?

but all this is not very practical, it is complicated, it needs a third channel and will probably give not sartisfying results!
reason:
1. from the mechanical point of view - it is very difficult to mount 2 cardioid-mics in that way back-to-back so close together.
2. the recording will definitively not be sufficient for the high frequency range (due to the length of the sound waves which are smaller than the distance of the capsules. also large diaphragm fig8's will have a problem there because of the large distance to the M-mic.

in theory the mid-microphone and side mic-capsules has to be placed on one point in the soundfield (coincident setup). i would like to recommend to use a 'real' small diaphragm fig8 microphone to do M/S seriously. all other experiments may be interesting but will not satisfy you, i guess...

[boojum]

Slight hijack: Williams describes a 3 card array which I have been experimenting with. I like it a bit better, so far, than MS for what I have used it on, choral.

Cheers

[desotoslo]

Jim, I've often wondered the same thing! I am very curious to try it out and see what happens.

Boojum, great, thanks for the post about the 3 card array. I've been meaning to try that out, too.

edit: funny... now that I look at the image close up, it's basically the equivalent of M/S with 3 cards, give or take 10 degrees at a multiple of two. It's interesting that Williams(?) eschews the equilateral triangle in favor of the obtuse and acute.

Cheers,
David

[boojum]

Originally Posted by boojum

Slight hijack: Williams describes a 3 card array which I have been experimenting with. I like it a bit better, so far, than MS for what I have used it on, choral.

Cheers

I have also used it on a bluegrass group with good results. The sound field seems broader. Of course there is the same control over the side channels vs the center channels as in MS. I generally mix it like a Decca Tree: mid down about 2dB. If you are interested I can post a clip somewhere of each. I ran a figure eight right above the mid card for a standard MS and recorder the four channels simoltaneously. The clip I have is of a local chorale in rehearsal.

Williams arrived at his configuration of considerable experimentation. It is in his first book which is a great reference book for mic arrays.

[Audiop]

Cool thread. I happened to spend some time this evening thinking about the arrays mentioned in this thread and started to think about a three card setup where the L and R cards is used to emulate a fig8 as side mic.

I will try it to see what it gives.

Correct me if I'm wrong but one would need to record three channels, mid to one channel and copy the L and R channels inverted and then make a R - invL (R minus inverted L) in the right channel and L - invR in the left channel, correct?

Then we have three channels which can be balanced for M and S.


/Peter

[boojum]

Originally Posted by Audiop

Cool thread. I happened to spend some time this evening thinking about the arrays mentioned in this thread and started to think about a three card setup where the L and R cards is used to emulate a fig8 as side mic.

I will try it to see what it gives.

Correct me if I'm wrong but one would need to record three channels, mid to one channel and copy the L and R channels inverted and then make a R - invL (R minus inverted L) in the right channel and L - invR in the left channel, correct?

Then we have three channels which can be balanced for M and S.


/Peter

Peter, if you run the Williams 3 card array just record the three channels. In post pan your left channel hard left, you center channel not at all and you right hard right. I back off the center channel some, usually around 2dB but will experiment with that some. When I get it where I think it should be I export the three as a single two channel stereo file.

If you want to use the 3 card array as input to MS, I would pan the left channel hard let, the right channel hard right and combine into a stereo track emulating your fig 8 track. Then I would just use the VoxenGo plugin to convert it to regular stereo.

The main drawback that I can see is phase difference. The MS is an XY array and the mics are as close as possible to maintain phase coherence. With this 3 card setup you lose that phase coherence. I have no idea the effect. I have not tinkered with it. It might be a better way, kind of a spaced array/MS setup??

[Audiop]

Yes, different techniques. For the card-MS-thing I thougth about putting the mic's as close as possible.

I will try the Williams set up as well. Thanks for input.

It's true that non-coincident MS with three card's will give some phase-effects but that is true for any spaced array such as AB, ORTF, NOS and so on.

Try everything once before you die right? ;-)


/Peter

[Nobilmente]

Quite some time ago now, I recorded a live event using three cardiods in a coincident set up. This was when I first started recording, and I did not have a fig 8 microphone.

I used a pair of SDC side address cardiods for the L & R (180 degrees back to back) and a SDC for the centre mic forward facing. I arranged the L&R pair as you would with fig 8 mics in an upright (end to end) position facing L&R. Between them I left a gap into which the forward facing cardiod (front address) fitted. I recorded them onto three tracks and adjusted them afterwards.

I was just experimenting and it worked ok for that concert, this was in the early 70's I think. When I mentioned it years later, some engineer laughed and said, 'You nearly invented the Soundfield!"

It was the side address cardiods that made it easy to set up. At that time being able to make adjustments after the concert was quite a novelty for me.

With the knowledge I had at that time, I didn't really find any problems with it at all. I haven't used it since.

[John Willett]

Originally Posted by Audiop

Try everything once before you die right? ;-)

Except for incest and morris dancing (as the quote goes).

[Audiop]

The first is a given but I can't promise anything about the second one. I don't know what it is but it sounds like fun!!


/Peter

[John Willett]

Originally Posted by Audiop

The first is a given but I can't promise anything about the second one. I don't know what it is but it sounds like fun!!

Morris Dancing is English Folk Dancing.

[jnorman]

in the top photo, they are each holding large, side address cardioids in a 6-card williams array...
i have no idea what the weirdos in the second photo are doing.

[audibell]

The weirdos in the 2nd picture are triumphantly waiving their sisters' knickers in the air, preparatory to doing what, I couldn't say.
WT

[John Willett]

Originally Posted by jnorman

in the top photo, they are each holding large, side address cardioids in a 6-card williams array...
i have no idea what the weirdos in the second photo are doing.

Originally Posted by audibell

The weirdos in the 2nd picture are triumphantly waiving their sisters' knickers in the air, preparatory to doing what, I couldn't say.
WT

[SaraLs]

Originally Posted by John Willett

Ummmm...never mind, I won't touch that!