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Old February 15th, 2004, 11:15 PM   #1
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Stereo Miking Techniques (M/S help please!)

Thanks to a previous thread I got my feet on the ground and have been doing searches and reading up as much as possible.

I know I want the Oktava, and the rest I am unsure about as of yet (this is where your help comes in!)

I see that M/S seems to be a popular stereo technique, and I THINK I understand it...the versitility of being able to alter the stereo spread seems appealing...EXCEPT for that darn side mic!

A figure of eight microphone?! I have searched and searched...and about two or three have come up. It seems to me that either this set up is WAY out of my price range, or the side mic has some other name

Okay, so here are my questions:
- Are figure of eight microphones called anything else? How much do they cost
- Is the figure of eight mono sound? If so, how does this part work...if the mic is picking up both L and R...how! The hookup?
- Is it possible to use a regular stereo mic AS a side mic in the M/S set up? Pros/Cons?

Okay, I think that's it for now
Thanks for your time!
Rob
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Old February 16th, 2004, 01:07 AM   #2
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Rob
It's no mistake, the figure 8 is expensive. I can't remember if I gave you this link. Don't listen to everything people tell you (including me)

http://www.oade.com/Tapers_Section/faq-mic.html
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Old February 16th, 2004, 01:21 AM   #3
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yep, I read up on that...the other one I looked at was X-Y but...I don't know...it just doesn't seem to be (in theory) what I want.

It sounds good for getting a wide pattern...but what I liked about the m/s was that you could keep 1 hypercardoid directly positioned at the main sound source. This way I have a mono track of specific voice/whatever else I would like to focus on and then a mix of background with the side channel...and I can fidget around with the differences.

If you had any insight on the last 2 Q's that'd be really great (or anyone else!!!)


Thanks again,
Rob
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Old February 16th, 2004, 04:51 AM   #4
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This mic does M/S stereo...

http://www.audio-technica.com/prodpr...ST_english.pdf

It says it has a line-cardioid and a figure-of-eight element and that it is capable of M/S stereo. It will probably cost you $700...

I haven't used that microphone and I am absolutely no expert in the field (just learned about M/S stereo yesterday).
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Old February 16th, 2004, 09:38 AM   #5
 
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If you want a poor man's way of doing M/S matrices, you can always build an out of phase cable. It accomplishes the same goal. Just be sure your two identical mics are as close together as possible when recording, so that the sound wave cycle is the same when it hits both mics.
I'm surprised more Euro folk haven't chimed in here. BBC has been using this technique for decades.
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Old February 16th, 2004, 10:24 AM   #6
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Douglas, could you explain a bit more or hit me with a link? I'd like to read up on this one too.

thanks,
Rob
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Old February 16th, 2004, 03:35 PM   #7
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Most microphones that offer a figure 8 pattern are expensive large capsules
like the Neumann U89 or the AKG 414. I think Beyer used to make a
kick drum mic (dynamic) that looked a bit like the old 'Elvis' style Shure 55.
The Beyer offers a figure 8 pattern
that worked well when mic'ing congas (it looks to the sides), BUT
was very 'tubby' sounding (which is okay for somethings).

If you really want good M/S results in a single unit shotgun
check out the Sennheiser MKH-418.
And of course there's always the Schoeps $4500 kit of MK41 and M8
with the suspension system, cable, preamp, blimp and deadcat.

www.posthorn.com
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Old February 16th, 2004, 05:09 PM   #8
 
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You can build a cable that has reversed polarity on pins 2/3, and then plug that into your mic input/cam input.
You can also find small mixers with phase reverse that accomplishes the same task.
If the two mics are placed VERY close together, as close as physically possible, the same sound wave/pattern hits the elements of the mic at the same time. With one mic pointed at source, and the other mic at a 45degree angle from source, with one 180 degrees out of phase, you have the same thing as an M/S system.
A quick search on Google for M/S mic, phase turned up a buncha responses. what looks like a good one is
http://www.radiocollege.org/readingroom/articles/sm/mic_techniques.html
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Old February 17th, 2004, 08:08 AM   #9
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<<<You can build a cable that has reversed polarity on pins 2/3, and then plug that into your mic input/cam input.>>>

Hold on here. M/S takes three channels in *order to keep control*
of the amount of ambient sound in the stereo mix.
So, how do you make it work with only two channels? You plug in the first mic (let's use the hypercardioid)
into channel 1. The 2nd mic, which traditionally a figure 8 patterned capsule
is sent to channel 2.

Later in post you *pan channel 1 to the center of the stereo mix*
and then *take channel 2 (fig 8) and duplicate/split it*. The original CH2 you
hard pan left and the duplicate you phase reverse and hard pan right.

The amount of ambience is then determined by the amount of
channel two and its phase revsersed twin's levels in the mix.

Hit the mono button and the two "ambience twins" cancel each other out and
leaving the hypercardioid's signal (mostly) all by itself.
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Old February 17th, 2004, 08:37 AM   #10
 
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The out of phase cable goes on one mic only, with the other end of the out of phase going to 2 mic channels. The signal is out of phase from the other mic. The two are combined either in mix or post stage, they can be muxed at any point. I've got one, as I say, I learned it many years ago from a guy at BBC when we did a project together. Just doing a quick search of google, I found lots of references to it, cuz I'm too lazy to type much.

http://homerecording.about.com/library/weekly/aa112899a.htm

http://www.turneraudio.com/tech/stereomic.html

http://www.modernrecording.com/articles/soundav/link2.html (wiring diagram here)

http://www.transom.org/tools/recording_interviewing/200106.stereomicrophones.jtowne.html
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Old February 17th, 2004, 05:00 PM   #11
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M/S is ideal for video because it is 100% mono compatible, whereas other stereo techniques can cause distortion effects when mixed down to mono.

Unfortunately I don't think you can buy a cheap figure of 8 mic.
You're talking of over $1,000 for a Sennheiser MKH30 or a Schoeps CMC6/MK8. You would then want an equally good mic for the Mid channel, e.g Sennheiser MKH50 or Schoeps MK41, which would be another $1,000+.

I would doubt that it is worth it unless you're recording classical music. Also the quality of the mics is wasted if you are recording direct to DV camera. You would need to record dual system, with a top quality AD converter. Top quality mics are quite cheap to hire though.

The Sennheiser MKH418S is a very good shotgun (MKH416) with a relatively cheap figure of 8 mic built in, just to give stereo ambience, but it is over $1,000.

Why not just spend a few hundred dollars on a pair of matched Oktavas and try out X/Y stereo and spaced stereo arrangements?

Patrick
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Old February 18th, 2004, 02:07 AM   #12
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Doug, I read every one of those, and if you truly can do m/s with 2 hypercardoids, I definately missed it...I read as best I could.

What if you use a oktava and one of those cheaper T bar shaped stereo mic's? Would that work okay for m/s?

As it stands I guess I am going to be getting 2 oktava's for X/Y

Also, avr.ca hasn't responded and the best deals for oktavas all use cardoids, would using a cardoid setup be that much worse? (using both indoor and outdoor)

thanks everyone!
Rob
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Old February 18th, 2004, 02:17 AM   #13
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wait...maybe I do understand...

From: http://www.transom.org/tools/recording_interviewing/200106.stereomicrophones.jtowne.html
Quote:
In order to decode these two signals to make stereo, you must mult (or copy) the figure-8 mic's signal to two channels on a mixer and flip one channel out of phase. Using three faders, you can have lots of control over the sound, adjusting the ratio of middle to side info, or the size of the stereo field, etc. Generally one would pan the cardioid mic in the center, and the other channels hard left and right. But by varying the pan of the side channels, or simply the relative volumes between mid and side, one can have a tremendous amount of control over the focus, image and size of the audio "picture."
I still can't fully wrap my head around how this is stereo though...if there is a car racing by from left to right...and you are recoding a mid and, say 45 degree angled side mic to the left, how do you get a right channel that actually is right? Maybe it does work...sorta fake like...It seems like the answer is on the tip of my tongue...or brain i suppose.

Now, if I am purchasing the Rolls MX4s Mixer...I would pan the mid oktava to the left channel, and then the side oktava to the right, and then some how mix it up in post?

How DO you mix M/S in post?

Thanks again, and if I am totally wrong on some (or all) things, feel free to tear me apart!
Rob
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Old February 18th, 2004, 02:23 AM   #14
 
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If you read the http://www.transom.org/tools/recording_interviewing/200106.stereomicrophones.jtowne.html page, and look at the
http://www.transom.org/tools/images/msmatrix.gif image

You can see how the split cable makes up for the figure of 8 mic. It's 2 signals from the same mic, one in and one out of phase, matrixed at the mix console or in post.
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Old February 18th, 2004, 09:08 AM   #15
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"Also, avr.ca hasn't responded " Jason was out sick, try calling.
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