Re: M-S vs. X-Y for field use
 

Brian's comment about the golf match is interesting.

Brian, am I understanding you correctly, they went to air with raw M/S?

Regards,

Ty

Re: M-S vs. X-Y for field use
 

Ty I think Brian meant that an M/S source mic was matrixed very wide so the S content was greater than the M so it would look out of phase as a stereo signal.

I have had this happen a lot when mixing pro logic and using the AMS Neve AB-wide control to increase the S content but it then makes a phase meter on a chromatec go negative.

I have never heard of automatic phase flippers though and all I ever got was a phone call from an inexperience QA person who didn't understand phase meters or how pro logic mixes can cause this and once I tell them to check the mono mix all has been OK.

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

I'd be interested in Jim's recc for a plugin, but here's how I did it.

Matrixing M-S to Stereo looks like this:
L = M+S
R = M-S

Think about how you'd set that up on a timeline: A single M track panned center, an S track panned hard left, and an inverted S track panned hard right. Group the two S tracks, and adjust the gain between this group and the M track to find the spread and image you want.

So, remembering algebra, if we use the math to de-matrix from Stereo to M-S, it looks like this:
M = (L+R)/2
S = (L-R)/2

Have I got that math right? If so, to set up on a timeline, you'd split your L+R file into two tracks, the method differs between NLEs/DAWs. Pan each track center and render; that's your M clip. Now, invert the phase of the right track and render, that's the S clip.

(We've ignored the "divide by 2" step in deriving our M & S, but do make sure you're not overmodulating the renders, you might need to reduce master gain before rendering.)

You've dematrixed, now start a new project and set it up as above, L=M+S, R=M-S and dial your spread!

With some judicious grouping, you can do it all on one timeline, the dematrix and new matrix back, but that gets needlessly complex, too easy to make a mistake, I recommend rendering as above.

Why do it the easy way with a plugin? This is so much more fun, and better learning, too! But after you've done it once and said "isn't this cool" you could go right to using a plugin... you'll know what it's doing.

(Won't my ears be red if I've flubbed the math, it's been a few years since I dematrixed, and a few decades since Algebra!)

Re: M-S vs. X-Y for field use
 

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.

Re: M-S vs. X-Y for field use
 

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

Fran

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

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?

Re: M-S vs. X-Y for field use
 

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.

Re: M-S vs. X-Y for field use
 

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.

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

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.

Re: M-S vs. X-Y for field use
 

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!

Re: M-S vs. X-Y for field use
 

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

Re: M-S vs. X-Y for field use
 

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.............

Re: M-S vs. X-Y for field use
 

Uh-oh!

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

Less is usually more.

Regards,

Ty Ford

Re: M-S vs. X-Y for field use
 

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. :-)

Re: M-S vs. X-Y for field use
 

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?

Re: M-S vs. X-Y for field use
 

Well, then you have to fiddle with precise placement of the figure of eight.

How about an AT 4027?

Ty Ford Audio and Video: AT835ST AT815ST Are Now BP4029 and BP4027

Regards,

Ty Ford

Re: M-S vs. X-Y for field use
 

No contest - the Ambient ATE 208 EMESSER is the best small, single diaphragm, fig-8 at a reasonable price.

I think it's about £600 and a lot cheaper than the Sennheiser, Neumann MBHO and Schoeps (all of which are also single diaphragm genuine fig-8 mics and not made from back-to-back cardioid capsules). Quality is up with that of Schoeps at a much lower price.

There is nothing cheaper that I would consider at all - unfortunately, fig-8 mics are more expensive than other patterns due to the design required to get them right and the low numbers sold compared to other patterns - but the Ambient is definitely the best value.

Re: M-S vs. X-Y for field use
 

I had a bit of fun using the Beyer M201 and M130 dynamic/ribbon combo a few years ago but settled on the sony prosumer ECM-MS957 as I rarely use stereo mic's these days!

My main pro stereo mic used to be the soundfield ST250 but I sold it several years ago as it was just too big for practical use.

Re: M-S vs. X-Y for field use
 

If it's a true figure-8 (i.e. not two cardioid capsules) then the diaphragm (or ribbon) is completely open on both sides, with no baffling to reduce movement. That does make them very susceptible to wind noise.

Back when I was 16 yrs old and working in AM radio (remember AM radio?!) I used to sign off the transmitter by slowly swinging a regular broom past an RCA BK11 ribbon mic. The LF output pulse was so strong that it tripped the plate overload relay on the transmitter and put the station off the air! So yes, you need wind protection with a true figure-8 mic.

I'm rather surprised that you don't like your mono shotgun with a bit of stereo ambient mixed in.

Have you ever considered using your mono recording with a bit of stereo synthesis? If you do it right, you can preserve the LF in phase on both channels, give a bit of stereo spread to the upper freqs, and yet retain 100% mono compatibility. It wouldn't be real but OTOH you wouldn't have to deal with audio pan direction reversing when you cut to a reverse camera shot.

Re: M-S vs. X-Y for field use
 

Thanks everyone.

It's not that I don't like the result, just that it's quite a lot of extra work for a one-man-band, especially since one sometimes doesn't have much time to set up at a new location. I've also had trouble synchronising the ambient track (imported from minidisc) with the video track. A couple of times I ended up with a strange echo that sounded as though I was recording through a drainpipe! But I guess that's a topic for a different thread...

(BTW I use a Sony MS957, too. Must get an XLR-5 to 2xXLR-3 cable made up for it some time - does anyone know where I can find the pin assignments for it? Sony refused to tell me!)

The Emesser sounds like just the mic for the job, though it's almost the price of an AT BP4029.

I've also got to work out what I'd have to do in my NLE (Avid Liquid 7.2) to mix M/S on the time-line. It certainly doesn't have any pre-set for it, so I'd have to "roll my own". I'm not even sure if it can invert an audio track. If it can't, then choosing a mic is a bit academic. OTOH, it will be an interesting question to ask when choosing my next NLE (since AL is obsolete now).

Re: M-S vs. X-Y for field use
 

No two machines will stay perfectly in sync unless you have a fairly sophisticated setup. Usually you can get away with less than perfect.

Start both recorders at roughly the same time (just for the sake of convenience). Then, located where both mics will pick you up OK, say something like, "This is the head sync" and clap your hands once (or snap your fingers, if you're really close to the mics.

Let both recorders roll continuously until you've completely finished the shot. Then say something like, "This is the tail sync" and clap or snap again.

Use your video recording as the master, find the exact location of the two claps, and find out the exact duration of time between them. (And by exact, I'm talking about the actual number of audio samples.) Now, separately, open your minidisc recording (I'm always surprised that those still exist). Find the exact duration of time between the two claps. Then use your NLE to stretch of shrink the minidisc audio until the duration exactly matches the duration of the audio track from the video recording. Line up the two head claps, double check that the two tail claps are lined up, and you're hopefully good to go. (I say hopefully because one or both of the machines might not have a constant speed... it might be speeding up and slowing down during the length of the take. That means you'll never maintain absolutely perfect sync throughout the take. But try the above, and see how it sounds. Hopefully it will eliminate the phase filtering that you've heard in the past.

Re: M-S vs. X-Y for field use
 

The XLR -5 connections for stereo are..

Pin 1 = Ground / shield
Pin 2 = Left +
Pin 3 = Left -
Pin 4 = Right +
Pin 5 = Right -

There are the connections used by Shure VP88 stereo mic, Audio Technica stereo mics, Sony mstereo mics as well as any camera that uses a 5 pin XLR for inputs or outputs.

And if you need a breakway cable for mixer - camera connections use a 7 pin XLR and use (Pins 1-5 the same as a stereo cable) and Pin 6 = Left return, Pin 7 = Right return.

Re: M-S vs. X-Y for field use
 

On old analogue stereo mixers, a common solution for mixing M/S was to use a Y split. The mid signal goes to one fader, panned central. The side signal is split, and fed to two channels, one panned left, and the other right. If the DAW or real mixer has a polarity button (often labelled phase), then prod that on just one channel (I usually use the right). If your DAW or mixer doesn't have this facility, when you solder up the Y split, just swap pins 2 and 3 on one side of the split.

Shove the mid channel up and you have mono. Bring up the two side faders and you bring in the width. Works fine!

Re: M-S vs. X-Y for field use
 

The Ambient EMESSER I mentioned above was specially designed to be less susceptible to wind noise than other mics.

It was designed after Ambient found that the Schoeps fig-8 suffered from wind too much.

Re: M-S vs. X-Y for field use
 

You *have* to polarity-reverse the right, or your stereo image will be left/right reversed.

Re: M-S vs. X-Y for field use
 

Unless the Side mic is facing the wrong direction (i.e. with the front of the mic facing right, rather than left).

Indeed, there are a few potential problems for the inexperienced MS-er.

Re: M-S vs. X-Y for field use
 

I can totally agree with that and for new users it is probably best to use a self contained M/S mic that outputs an A/B signal.

As said I now use the sony prosumer mic's and even the small ECM-MS907 can give good results and has been handy to carry with me all the time with a minidisc recorder for grabbing sound effects, or I use the ECM-MS957 with a rode PG1 pistol grip and suspension.

They have switches for 90 or 120 degree angle and can be great for use with cameras that have stereo 1/3" minijacks and no phantom power as they are both battery operated, I also use them with my canon HF11 AVCHD minicam for interviews or off camera sound.

Re: M-S vs. X-Y for field use
 

No, I disagree - when I started using MS many years ago I bought a cardioid and fig.8, connected them up and used them.

No problem at all.

Re: M-S vs. X-Y for field use
 

With best respects John a great deal of the video camera and DSLR users are not full audio engineers and I would think they would struggle with a full M/S rig as a rode videomic or an NTG2 is their level of mic kit.

Re: M-S vs. X-Y for field use
 

I would agree with Gary on this. Sorry if I offend anyone but generally videographers are notorious for screwing up production and post production audio.
Keep it simple.

Re: M-S vs. X-Y for field use
 

I would have to agree Gary, how many times has the subject come up about 'what is the best camera mic for recording dialogue' or 'what is the difference between mic and line level'
For many DSLR users and low end videographers audio seems to be a stumbling block.

I still believe that MS is beyond the capabilities of many video production people.....even rolling off the bottom end or using a HPF in the editing process is to much for some people.

Re: M-S vs. X-Y for field use
 

Even with digital recording meaning that M/S as a source can be recorded and handled more accurately than with analogue and it's inherent phase and combing I know of several location recordists who did not understand the post processes involved and have made huge mistakes recording M/S on location so to expect a videographer to handle it is asking far too much.

Even I have never recorded M/S in over 33 years but have used the mic technique and always with an M/S designed mic that outputs A/B.

You can use the M/S encoding technique Paul highlighted but it is hugely level critical and you can collapse or over anti phase the resulting signal very easily, I personally have always had AMS Neve Logic or DFC digitall consoles with AB-wide contraols but as most location recordists don't even bother to ident what is dual mono. M/S, A/B or radio mic and boom it tends to be impossible to handle recorded M/S in post and certainly most editors will not have a clue what is going on.

Now for static orchestra or ensemble recordings it may be easier but for me I would still be going for an A/B recording from an M/S mic but may put an M/S signal on a spare couple of tracks if I had them available.

Re: M-S vs. X-Y for field use
 

The bad news is that AL can't invert an audio track. However, it can accept VST plug-ins, which I'd forgotten all about (a legacy of the brief period when Pinnacle owned Steinberg, before selling them on to Yamaha). This means one can either use a simple mono inversion plug-in on a copy of the Side track, or use an M-S processing plug-in (e.g. Voxengo MSED). There seem to be quite a few alternatives, most of which are free. I've not actually tried any yet so I don't know which ones might be good, bad or indifferent, but at least I should be able to do it with Liquid. Hooray for open interface plug-ins! Anyone tried any of these VSTs, and got any personal recommendations, pro or anti?

Re: M-S vs. X-Y for field use
 

When I started recording with MS I was certainly not a "full audio engineer" - I was a lad recording for a hobby in my spare time and learned by experimentation and reading magazines. I had no training at all.

As a novice, I found it very easy to pick up.

Are videographers really so stupid that anything slightly technical stumps them completely?

I think not - I certainly hope not - otherwise they would never be able to operate the camera, which is a lot more complicated than simple MS recording.

Re: M-S vs. X-Y for field use
 

The free Voxengo you linked to is very good - I use it myself.