M-S vs. X-Y for field use

[Bruce Watson]

Originally Posted by Brian P. Reynolds

If you are doing ANY production that is in stereo.... it doesn't matter if its XY / MS / AB / ORTF or any other form ALWAYS check the mix in mono as well........ALWAYS ....NO exceptions !!!!!!!!

I'll bite -- why? In particular, if it's never going to be heard in mono, why check in mono?

[Gary Nattrass]

Originally Posted by Bruce Watson

I'll bite -- why? In particular, if it's never going to be heard in mono, why check in mono?

You can never asume that something may never be heard in mono especially for broadcast and if the capsules are out of phase they will cancel out.

I personally prefer using a stereo M/S mic on location but recorded as a matrixed A/B signal as the M capsule is always pointing at the sound source.

[Steve House]

Originally Posted by Bruce Watson

I'll bite -- why? In particular, if it's never going to be heard in mono, why check in mono?

Because a lot of your listeners will actually hear it in mono.

[Brian P. Reynolds]

Originally Posted by Bruce Watson

I'll bite -- why? In particular, if it's never going to be heard in mono, why check in mono?

A lot of recorded material gets played as mono... many YouTube clips are mono (phones and tablets) even some laptops have problems.
Subwoofer (low frequency material ) is played as mono, even wide screen TVs have subwoofer systems in them.
Theatre / stage shows / productions are mono.
MP3 / MP4 files often have poor channel separation at lower frequencies, resulting in virtual mono results.
PA systems are mono.

SO if you use a bad mic setup like 'over wide MS' or poorly aligned XY phase errors WILL occur, this will result in frequency cancellations in your mix / recordings.

So if your recordings / mix EVER ends up on YouTube, mobile phones, tablets, laptop computers, Broadcast, PA, DVD's, Theatre, or played on a big screen make sure that you have correct phase correlation......

[Rick Reineke]

Hence my suggestion to use a single 'stereo' mic which should be mono compatible w/o alterations. But I would check mono compatibility anyway.. via listening to L+R summed AND a scope.

[Seth Bloombaum]

Originally Posted by Brian P. Reynolds

...SO if you use a bad mic setup like 'over wide MS' or poorly aligned XY phase errors WILL occur, this will result in frequency cancellations in your mix / recordings...

This is not correct. MS, whether mixed "overwide" or narrow degrades to perfect mono. Stereo information from the left perfectly cancels the stereo info from the right channel when summed to mono, and what remains is center (the Mid mic). Now, if you were using an M-S mic as your only source, then mixed the Mid channel down to zero, you could end up with very little gain when your stereo mix is summed to mono. But I've never been tempted to do so when mixing M-S... because the process is to dial the stereo spread to taste, and it always sounds best with a significant amount of mid gain.

You'd have to go way past "overwide" before you lost significant gain on summing L+R to mono...

A "poorly aligned XY" array becomes a near-coincident pair, rather than the coincident pair that you're supposed to use with this technique and a pair of mics. You could describe ORTF as a poorly aligned XY, or even look at AB that way. Phase errors will occur, yes, but what is the audible result of this? I recommend listening, trust your ears!

But, as Brian and many have pointed out, checking out how your mix sounds in mono is really a best practice no matter what stereo techniques you might be using.

Sorry to go into rant mode here, but the way that MS works in mono is a strength of the technique, not a weakness. Granted it is possible to screw it up...

The best way to screw up mono compatibility is to have a phase problem in your monitoring, do pay attention to polarity all the way from your sound card to the monitors and get it right! Likewise, in any playback system.

Check all mixes in mono all the time. X-Y, A-B, ORTF, and yes M-S too can all be screwed up if you're not careful.

Originally Posted by Rick Reineke

Hence my suggestion to use a single 'stereo' mic which should be mono compatible w/o alterations. But I would check mono compatibility anyway.. via listening to L+R summed AND a scope.

Well... I've had a lot of fun with two cardoids in X-Y and ORTF, and the mono didn't sound bad. The conventional wisdom is as Rick says here... but... unless screwed up in some other way, even ORTF, which the engineering math says should have the greatest phase "errors" can sound fine in mono, in my personal experience.

There are some accepted truths in this business that are worth testing for yourself! The theory behind phase cancellation and comb filtering is solid, it's good engineering and math, but in practice it is not so cut and dried, everything seems to be a lot looser when you have microphones in real spaces with real sources... in my experience.

If it sounds good, it is good - was that Count Basie or Duke Ellington?

[Brian P. Reynolds]

Seth.... have you ever broadcast MS mics LIVE to air?

I did a golf tournament in the early days of stereo TV using MS mics, to match some of the wide pretty shots we set the stereo mics to wide (nothing tricky JUST the 'wide' setting on the mics).

It went like this.... program open music xfade to stereo FX (wide MS mics) for 10 seconds to established the location, cue commentary..... BUT what occurred at ALL the transmission station(s) across the country was the auto phase correction detected an out of phase signal so it corrected it and phase inverted R channel to bring it into 'what it assumed as correct phase', and when the commentary started the mono commentary was completely canceled out.......... YEP thats right NO commentary across the country..... and ALL caused by some MS mics set to the wide setting on the mic.

So don't tell me there is NO problems with MS mics !!!!!!!!!!!!!!!!!!!!!!!

Since that incident many years ago I now use XY set VERY wide almost to a point of having a dip in the centre of the audio image, the mono commentary and spot FX sits in there nicely giving a VERY wide spatial sound image that suits wide screen TV fantastically.
This XY stereo technique is what I have used for the past 25+ years in live to air sporting Outside Broadcasts.

And thats why I have ALWAYS said that EVERYbody that has some ability to change the sound of a mix MUST be aware of how MS works and how it can be used and more to the point how it can destroy a Broadcast....
If you ever do a movie or music record using wide MS how do you know what will occur to the material you have created many years down the track...Could you be creating future problems for others?

[Gary Nattrass]

With best respects Brian that is a problem with the transmission system and not a problem with M/S mics.

If networks chose to put auto phase correction across their output that is not my problem as a sound supervisor if I am sending a valid stereo signal.

I appreciate what you are saying but if that was the case then pretty much every dolby pro logic mix that has ever been done would cause the same problems so it is not specifically an M/S mic problem.

[Paul R Johnson]

For a moving object against a stationary background, although I don't use it much myself, I'd go the M/S route on this one, because of the complexity of the moving sound source. For a passing noise like maybe a Police siren, X/Y or even a spaced pair of omnis would be nice, for the passing object that has extreme length, like a train, M/S offers a more suitable recording method. Not so much for the actual stereo image, but the possibilities of controlling it afterwards. The only issue with M/S is when post is carried out by people who don't understand how it works.

[John Willett]

Originally Posted by Doug Boze

Hey all,

I've been away for a long, long time (where does the time go?) and want to get back into my old hobby. I've been lurking here most of a month, trying to get a grasp on what's what and what species of lily is being gilded at the moment, and it's bewildering.

I have a Canon XL-2, CAVision matte box with two trays, bellows lens hood and rod system, a Manfrotto 503 head and either Amvona (el cheapo) CF sticks or, for brute work, Bogen 3183 sticks, an AT-825 single-point stereo mic inside an old-style Rycote WS-4, which is attached to the right-hand pan handle location using an amazing birch dowel (pat. pending).

My hobby has been railfanning, shooting trains around the Pacific Northwest. At one time I even thought I might make it a living, being on layoff, but about the same time work reared its ugly head and I went back to my day job as a machinist.

Looking at where things are today, I think I'm getting an idea of what I want as far as an upgrade to the HD world. So many things to upgrade, including audio. The AT-825 has served me very well, and the newer BP4025 would seem the logical upgrade unit. But I've been reading about M-S stereo, and now I only know just enough to be a hazard to my own judgement. I know the advantage to it as far as having an honest interview mic (not that I've ever done an interview) but the concept of spacial manipulation interests me.

Is it worthwhile to go the M-S route for my application? I was thinking of a pair of AKG Blue-line mics, using the CK94 and CK-93 and a Rycote WS AE kit. It's much pricier than the BP4025, but I was going to replace the WS-4 with a WS-3 anyway. The specs of A-T's BP4025 are very attractive, and the old AT-825 has been an amazingly sensitive, quiet, and forgiving mic. I'd be rather concerned about dynamic range and max SPL: wheel flange squeal will loosen one's teeth, I kid you not.

BTW, some years back I thought the Rode NT-4 was the bomb due to its specs. Well, the one I had was a bomb, so much so that I have zero interest in their product line. Maybe it was a factory reject that made it to market or maybe somebody damaged it and it was returned. Horrible device, yet all I read are lauds?

MS definitely.

The coincidental mics are much easier to windshield, direct and control than an XY pair.

I never use XY nowadays - if it's not MS, then I use ORTF or spaced omnis - but for whhat you suggest, then MS is definitely the best option.

My MS rig is Sennheiser MKH 40/30 and I have two of them.

[Bruce Watson]

Originally Posted by Seth Bloombaum

If it sounds good, it is good - was that Count Basie or Duke Ellington?

Ellington, one of my heros. Usually written as "If it sounds good, it IS good."

[Bruce Watson]

Originally Posted by Brian P. Reynolds

... mobile phones, tablets, laptop computers, Broadcast, PA, DVD's, Theatre, or played on a big screen make sure that you have correct phase correlation......

Hadn't thought about the small handheld devices. But the audio is so bad on those things that it would probably be difficult to hear any sound problems with them anyway. Still, something to think about.

[Seth Bloombaum]

Originally Posted by Brian P. Reynolds

Seth.... have you ever broadcast MS mics LIVE to air?

I did a golf tournament in the early days of stereo TV using MS mics, to match some of the wide pretty shots we set the stereo mics to wide (nothing tricky JUST the 'wide' setting on the mics).

It went like this.... program open music xfade to stereo FX (wide MS mics) for 10 seconds to established the location, cue commentary..... BUT what occurred at ALL the transmission station(s) across the country was the auto phase correction detected an out of phase signal so it corrected it and phase inverted R channel to bring it into 'what it assumed as correct phase', and when the commentary started the mono commentary was completely canceled out.......... YEP thats right NO commentary across the country..... and ALL caused by some MS mics set to the wide setting on the mic.

So don't tell me there is NO problems with MS mics !!!!!!!!!!!!!!!!!!!!!!!
...
If you ever do a movie or music record using wide MS how do you know what will occur to the material you have created many years down the track...Could you be creating future problems for others?

Brian, that's about the biggest broadcast sound nightmare I've heard of. I'm sure the recollection comes with some pain.

My broadcast TV days were pre-stereo... but I also had some problems with the processing done downstream of my console. The guy who trained me always listened to the transmitter return, because the compression/limiting done in Master Control was seriously screwy, and if I wanted the folks at home to hear a reasonable mix I had to monitor post of that processing. I got a rather serious dressing down after it turned out that the feed to cable distribution occurred pre of that processing, and the cable subscribers were hearing levels all over the place. The resolution was to make the (pre) air tape mix sound good, then management would be happy. "Sorry" to the broadcast viewers at home.

You know, the real problem was the compression/limiting setup done by transmitter engineers who had no f****ing idea what they were doing with sound.

I have to agree with Mr. Nattrass, above... though that's small comfort when management comes down on YOU!

One can hope that the days of auto phase "correction" without human intervention are gone, you'd think there would be all sorts of contemporary pop music that might trigger it, but probably the tradition continues somewhere. Presumably with a strong Mid signal in the mix it wouldn't happen. What mics were these?

BBC, on the other hand, mandated that all atmos / ambience be acquired in M-S, because of the graceful sum to mono. Don't know if that mandate is still part of the programming spec (I'm in the U.S.), but it was true for many decades.

But I hear your criticism, and I've been caught in the trap I pointed out earlier in this thread - there is theory, and there is experience. We need to have our practice informed by both. And though I'm a huge fan of M-S, if it ever comes up that my work might make it to Australian broadcast, I'll keep what you wrote in mind!

There's only so much I can do to prevent problems down the road; it really isn't my responsibility to think about every possible future screwup, only the common ones. My real responsibility is to my employer-of-the-moment; the best practices that will support their goals.

[Brian P. Reynolds]

Originally Posted by Seth Bloombaum

BBC, on the other hand, mandated that all atmos / ambience be acquired in M-S, because of the graceful sum to mono. Don't know if that mandate is still part of the programming spec (I'm in the U.S.), but it was true for many decades.

Many years ago I came across a copy of those BBC requirements in an old file.... BUT the other thing that was also mentioned that it needed to be recorded 1/4" tape @ 3 3/4ips or 7 1/2ips..... NOTHING else would be accepted. 1/4" @ 3 3/4ips Mono was the standard for voice.

At the time I would assume it would have been the logical choice otherwise location sound guys would have used crossed pairs of MKH816's.... AND the post production guys then would have been attuned to working in MS, these days people don't understand the technique let alone be attuned to using it.

[Paul R Johnson]

The automatic phase error problem was perhaps not the 'fault' of M/S but of the use of M/S mics that do the re-matrixing in the mic - as in without any attempt to listen to the recombining. Gary has one of the Sony mics that do this, but the width adjustment must be listened to - or the left to right differences can be extreme - especially when presented with a dead centre component in the sound field.

I suspect this just emphasises that there is is no 'correct' technique, just ones that are appropriate on a case by case basis.