M-S vs. X-Y for field use

[Fran Guidry]

Originally Posted by Ray Turcotte

Great discussion guys!

For Seth & Gary: I have a Sony ecm-680s Shotgun stereo mic in which the capsules are in m+s mode. However there is a chip in the mic that switches the signal to L+R stereo encoding for input to the camera. What can be done in post to get the M+S signal back?


Thanks in advance

Voxengo MSED Audio mid-side encoder-decoder plugin (AU, VST) - Voxengo MSED - Voxengo is the tool I've used.

Fran

[Gary Nattrass]

I now use this free plug in for Pro Tools to adjust the M/S width of an A/B signal in post:

Brainworx | bx_solo

This may also help people new to the M/S technique: http://www.brainworx-music.de/en/whatisms

[Jim Andrada]

I've also used it as well as Waves SI - both work just fine IMHO

[Ty Ford]

Originally Posted by Brian P. Reynolds

No Ty, it was a L / R FULLY matrixed output but the width setting was on the widest it would go (the mic used Sony ECM969 did NOT have an un-matrixed [raw] MS output).

The width setting controls change the ratio between M and S components, in the wide setting there is more S component than M component making the audio image very wide .... But if there is a sound (bird call, frog croak, car horn etc or any other sound) at 90deg to the mic on either the left or right it WILL result in an out of phase signal on the other side..... and if that sound is there long enough it will be regarded as being 180deg out between L & R and in a broadcast chain will possibly cause errors when going to air depending on the transmitter processing.

And its NOT just Sony mics that do this, I have been able to replicate the problem on ALL MS mics I have had acess to Shure VP88, Audio Technica [various models] , AKG and Sony [various models], I haven't tried the Sennheiser 418 but I am assuming it would be similar to other mics.

edit... Just checking the details on the Senni 418 it appears to be an UN-matrixed mic and ONLY has a discreet M and S outputs and NO Left / Right outputs.

Thanks Brian, got that and yes, in the 418S, the side capsule is behind the mid capsule. So any time you get 90 degrees off axis, the sound is impinging on both capsules simultaneously. If any of that sound comes in more than 90 degrees off axis, the stereo image wobbles. I've found a wobble point on both sides of an M/S capsuled mic (specifically M/S mics that have the Side capsule behind the Mid capsule) as the sound source goes behind the mic on one side and comes back on the other.

Regards,

Ty Ford

[Brian P. Reynolds]

Here is a comment made by another person that also used MS.....
And this is why I have been saying that MS is NOT a foolproof system, It MUST be used with care.
What would have been the expense been if many thousands of CD had been produced and the client had rejected the mix?

[Gary Nattrass]

Originally Posted by Brian P. Reynolds

Here is a comment made by another person that also used MS.....
And this is why I have been saying that MS is NOT a foolproof system, It MUST be used with care.
What would have been the expense been if many thousands of CD had been produced and the client had rejected the mix?

But an out of phase XY will also collapse and cancel in mono so it is not just down to M/S but down to bad operational practice.

[Brian P. Reynolds]

Originally Posted by Gary Nattrass

But an out of phase XY will also collapse and cancel in mono so it is not just down to M/S but down to bad operational practice.

On XY mic setups there is actually a lot less chance of operator error than in MS.
In fact XY, ORTF, AB and variations between using similar mics are actually a MUCH safer than MS.

Virtually ANY problem in audio can be attributed to 'bad operational practice', my attitude to what I do (mainly because it's live to air broadcast) is to minimise any potential problems.

[Ty Ford]

Whenever the venerable YAmaha DX7 came out, it was appreciated for some of its wide sounding stereo patches.

Problem was, to get that, they just took a mono sound, flipped the polarity and added it to the other channel.

So, yeah, when you use one of those wide patches when recording a song and keep it it stereo, no problem, but when you hit the mono button, POOF, keyboard goes away or way down.

Mono is everywhere. Even FM stereo "blends" down to mono when reception is compromised. Most overhead systems - mono. Most clock radios - mono.

Regards,

Ty Ford

[Greg Miller]

At one point, several years ago*, XM Radio was processing some of their channels to give a "wide stereo image" and, guess what: many listeners were complaining that the vocals were very low in level. Why? Because to get the "wide image" they were boosting (L-R) level compared to (L+R) level. The solo vocals, most of which are mixed equally to the L and R channels, were therefore way down in level, compared to what the original CD mixing engineers intended.

I experimented by re-mixing with (L-R) reduced by about -3dB, and the music started sounding normal again, with a better level to the vocals... that confirmed my suspisions about the cause of the problem. It simply demonstrates that "wide stereo" is just asking for trouble, regardless of the original audio source.

IMHO, this is not a technical problem. The problem is too many "hotshot kids," with no clue about the basics of audio, working in the engineering department (or, worse, in management). Of course this issue is not at all confined to XM.


* I don't know whether they've since ceased this practice. Over the years XM has lowered bitrate again and again, and it's no longer listenable.

[Gary Nattrass]

I agree wih Greg, phase checking and mono compatibility should still be part of the basics of audio engineering!

I was taught to ident and phase all mics when I started in 1980 when stereo for TV didn't exist but still follow the same procedures to this day, I am glad that even my digidesign 002 has a mono button for the monitoring!

[Ty Ford]

Greg, et al,

Right and FM stations "found" this "really neat box" that did basically the same thing in an effort to sound different on the air. Crap mostly.

This thread is reminding me of the Bedini Audio Spatial Environment box that did something very similar, but, and it's a big but....they had a mono center fill that you could dial up to fill the hole.

You see them on ebay every once in a while. Quite effective, really, because of the L+R to fill the hole.

Regards,

Ty Ford

[Brian P. Reynolds]

A friend just bought the new zoom H6 recorder and with joy he announces this wonderful 'NEW' mic that you can change and make super wide stereo.....
Looks like we are in for a couple of years of problems with MS on the forum with the H6.

REMEMBER .................check the mix in MONO..............ALWAYS.............

[Ty Ford]

Uh-oh!

::sigh:: Just because you "can" doesn't mean you "should."

Less is usually more.

Regards,

Ty Ford

[Colin McDonald]

Originally Posted by Brian P. Reynolds

A friend just bought the new zoom H6 recorder and with joy he announces this wonderful 'NEW' mic that you can change and make super wide stereo.....
Looks like we are in for a couple of years of problems with MS on the forum with the H6.

It appears that Zoom have cleverly made the M/S module too noisy to use, so that 'wide open sound' comes with its own built in waterfall. :-)

[Mark Fry]

To go back to the original discussion: I've been filming trains in the landscape as a solo cameraman for many years. Most shots involve panning the camera to follow the train. Sometimes you only need to move it a few degrees (e.g. when on a bridge or by the fence). Other times a shot can involve a wide pan and a change of direction (e.g. when looking down from a hill some distance from the line).

My normal arrangement is to use a mono short shotgun (Rode NTG-1 in a Rycote S300 basket) mounted on the camera. I plug it into the Left socket and the camera copies the signal to both output channels. It's simple and reliable. It makes the most of the sound from the passing train and minimises extraneous background noise, such as roads, factories, building sites, other on-lookers, etc. (you are not always out in the countryside, nor on your own!)

I've experimented with some different stereo set-ups, including on-camera X/Y, static X/Y and a static Sony M/S mic, wired to give normal L/R outputs. I've also tried recording my normal mono in camera and stereo to a separate recorder to add as an "ambience" track, but I keep going back to simple mono.

Reading this discussion makes me wonder whether I could add a Figure-8 mic on the right channel and mix my own M/S stereo in my NLE, probably keeping the S componant quite low, to give a sort of "mono with a feeling of space". I presume that I'd need to mount it on-camera with the mono mic, so that they move together as the camera pans. Putting it on a separate, static mount wouldn't work, would it?

One thing that might be a problem for my sort of outdoors recording: I gather that some fig-8 mics are very sensitive to wind noise. Is this generally true, or are some better than others?

So what Figure-8 mic would be a good match for the NTG-1 and the application, given a fairly limited budget?