Stupid question about M/S...

DrummerMan · Post by **DrummerMan** » Sun Apr 22, 2012 9:03 pm

So, I'm trying some front of kit M/S recording with this awesome new stereo ribbon I just got. Shit sounds really cool. Really, really cool.

I'm just recording the 2 channels from the mic, copying one of the "Sides" and flipping the phase, then hard panning the 2. Just like that it sounds great. My question is about mono compatibility. If I center pan the 2 side channels, they disappear. This of course makes sense because obviously flipping the phase on something and playing it simultaneously will make it disappear.

So, how then can M/S be mono compatible? What am I missing here? I feel like an idiot. Obviously people record M/S all the time, and that gets broadcast on things like the radio and TV where sometimes there's varying shades of gray between stereo and mono where a broadcast signal can live.

ANyone offer an explanation suited for a dummy? Thanks...

ricercar.record · Post by **ricercar.record** » Sun Apr 22, 2012 9:25 pm

sounds like you're missing the mid. The Mid-Side (M/S) micing technique requires two microphones, one bi-directional (figure eight) microphone for the side and one generally Cardioid patterned microphone for the Mid (I say generally because I have heard quite often people using omni or hypercardioid patterned for the mid). The reason Mid-Side is capable of offering total mono-compatibility is due to the fact that like you said, if you center pan the 2 side channels (like collapsing a whole stereo mix to mono would do) they completely cancel out due to the opposing phases, leaving only the Mid signal dead center. However, if you're not recording a Cardioid, Omni, or whatever microphone for the Mid channel, then you will be left with nothing, as you experienced.

DrummerMan · Post by **DrummerMan** » Sun Apr 22, 2012 9:32 pm

No, I've got a mid mic. The whole setup is a stereo ribbon. I know I still get the mid signal when collapsed to mono, but I was just curious if the whole idea is that you just lose all your sense of ambiance from the side mic in mono. That seems weird to me, it's just such a drastically different sound.

RickvH · Post by **RickvH** » Sun Apr 22, 2012 11:19 pm

I also find this puzzling, that having all the ambience cancel out is considered to be mono compatible. I suppose it's technically compatible, but hardly desirable. If I was striving for mono compatibility, I would prefer if some ambience was retained when the L and R are summed into mono.

jhharvest · Post by **jhharvest** » Mon Apr 23, 2012 12:16 am

RickvH wrote:If I was striving for mono compatibility, I would prefer if some ambience was retained when the L and R are summed into mono.

Have you tried an omni mid-mic?

RickvH · Post by **RickvH** » Mon Apr 23, 2012 12:33 am

jhharvest wrote: Have you tried an omni mid-mic?

No, I haven't, but that sounds like a great idea. I'm gonna give that a try next time.

RoyMatthews · Post by **RoyMatthews** » Mon Apr 23, 2012 6:10 am

Well, the reason it's considered to be mono compatible is because the sides disappear completely.

If you were using a spaced pair of omnis the sound would reached the two mics at different times. There would be phase cancellations between the two mics when summed to mono. This happens more or less with all stereo mic'ing.

M/S gets around this by completely removing the side microphone and any possible phase problems. In the end (in mono) it's as if you mic'ed the source with one mic.

If there's too much side info in the M/S blend there will be a greater collapse in the sound when in mono. I'd start wing the mid mic and bring in the side channels to taste and checking in mono that there into too much of a signal loss.

I also think it's important to remember that M/S is stereo because of the interaction of the three signals. Often people consider it pseudo stereo because they believe that the "stereoness" comes from the panned side mics. It real comes from how those side mics create new pickup patterns with the mid mic and then become L/R stereo.

Personally, I like M/S. I like being able to control the stereo with easily at the mix stage. It's nice to have the option of a solid mono drum sound but then bring in the side mics for the chorus. It has a lot of possibilities. But I also think that regardless with any stereo mic'ing technique you use you should check how the source sounds when summed to mono before you even record it. If is sounds good then it works and go for it.

I hope I'm making sense. I haven't had my coffee yet.

vvv · Post by **vvv** » Mon Apr 23, 2012 9:23 am

Nice explanation!

IOW, stereo incorporates the ambience; you give up the ambience when reducing to mono.

DrummerMan · Post by **DrummerMan** » Mon Apr 23, 2012 2:47 pm

OK, thanks for clearing that up! That's kind of what I was thinking, but I just couldn't remember in all the discussions I've read about M/S hearing about that side of it.

drumsound · Post by **drumsound** » Sun Apr 29, 2012 11:08 am

DrummerMan wrote:No, I've got a mid mic. The whole setup is a stereo ribbon. I know I still get the mid signal when collapsed to mono, but I was just curious if the whole idea is that you just lose all your sense of ambiance from the side mic in mono. That seems weird to me, it's just such a drastically different sound.

Remember, collapsing it to mono is the same as taking the side mic totally out of the picture.

jhharvest wrote:
RickvH wrote:If I was striving for mono compatibility, I would prefer if some ambience was retained when the L and R are summed into mono.
Have you tried an omni mid-mic?

This is a really good option

DokorderFreq · Post by **DokorderFreq** » Tue May 15, 2012 5:32 pm

Out of simply building my knowledge for the subjuct, I just found this data at the Universal Audio website. This looks pretty complete/thorough:

http://www.uaudio.com/blog/mid-side-mic-recording/

The omni mid mic idea is interesting...I gots some experimenting to do

Scodiddly · Post by **Scodiddly** » Wed May 16, 2012 7:25 pm

Definitely try a wider mic pattern for the Mid - figure-8 isn't going to give you much ambience unless you happen to have a concert hall behind it.

Nick Sevilla · Post by **Nick Sevilla** » Thu May 17, 2012 7:55 am

Hi Geoff,

I always use a regular cardioid pattern condenser microphone for the Mid microphone, then use the figure 8 mic for the sides.

This allows for enough ambience to remain when in Mono, after the sides have cancelled out.

An extremely important thing when using two distinct mics, is to align their capsules/ribbons exactly right on a plane in front of what you'll record.
This helps maintain phase coherency of the source signal.

Cheers

ericzang · Post by **ericzang** » Thu Jun 14, 2012 4:04 pm

As you have a stereo ribbon, rather than record in M/S, orient it so that it is like X/Y. I have found that I still can control the width with a stereo panning plugin (the width is generally wider than M/S), and because it is a stereo mic with properly oriented capsules, I don't get any (or minimal perhaps) phase cancellation when adjusting the stereo width or collapsing it to mono. I get this result with a Royer SF-12.

If the sound source stretches wider beyond the 90 degree angle of the two capsules' orientation, I have read that technically there could be some issues, though I haven't noticed anything too obvious yet.

rocksure · Post by **rocksure** » Mon Jul 02, 2012 4:30 pm

Mid-side is definitely a pretty cool method when used in the right context. The fact that the side ambience disappears in mono when using a cardioid mic in the center is why I think it is favoured in broadcast. Interestingly though, in Alan Blumlein's original patent of the m/s technique he used an omni mic as the mid-mic.
If anyone is interested in doing a bit of reading on different stereo micing techniques, I wrote a couple of tutorials that cover the various methods. I will post links to them here:

http://rocksuresoundz.com/2012/07/01/st ... es-part-1/
covers X-Y,ORTF,DIN,NOS and spaced pair methods

http://rocksuresoundz.com/2012/07/02/st ... es-part-2/
covers mid-side,Blumlein pair and Decca Tree methods

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