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Old 01-14-2012, 11:56 PM
flagstaffcharli flagstaffcharli is offline
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Default Mid-side technique?

So after reading through the whole "evolution" thread again (and deciding I have no business buying anything more until I thoroughly get to know my gear) I sat down and did some recording of a solo guitar piece today.

Basically, I set up four 2X4 ATS broadband panels and made a wall for my mics similar to how Fran used 2 panels in his recent thread on the subject. The only difference was I opened it up a little so that I would get more reflection from the sides. I pointed my KM184 at my guitar and got a sound I liked without too much fuss, and then I set-up my AKG414 to figure eight and put it in its M/S position beneath the Neumann.

I'd never done a mid-side recording here at home and mostly I just wanted to try out the technique to see how it worked. So I duplicated the side track, and then it took me forever to figure out how to invert the phase in my DAW. But once I got it... Wow! That's the best guitar sound I've ever been able to capture on my own. And it's really enlightening to play with the faders and see how the stereo image changes as you mess with the volume of the tracks. (In fact, I can see where mixing might be an exercise in restraint because of the temptation to keep turning up the sides!)

I'm just scratching the surface with this right now, but I see a lot of potential. I might try to replace the Neumann with my new Beyer M160 tomorrow just to see what the difference will be. The AKG is the only mic I've got to go in the side postition, so it's going to live in that spot for now.

I've got two questions:

1. I see people mentioning decoder software in a number of threads. I do see how you can use that software to sort of turn the stereo image, but in the case of recording a solo guitar that seems unneccessary. Is there any practical advantage to using the decoder software as opposed to just flipping the phase on a duplicated track?

2. Is there an optimum relative level for each mic? I just got what I thought were healthy signals where there was no danger of clipping. It seemed to work well, but I got to wondering if the AKG should actually be quieter than the Neumann since it is mainly capturing the reflections. I don't know...

If someone wants to recommend a source where I could read more about this technique, I would be grateful. I might try to put a couple instrumental pieces on an upcoming CD, and I suspect I'm going to spend quite a bit of time experimenting with mid-side recording over the next few weeks.

As always, thanks!
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Old 01-15-2012, 12:08 AM
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Chuck, glad your having fun with MS. A couple of things:

The decoders are just convenient. Using them lets you record on a stereo track and treat the signal as stereo, with a "width" knob. But it's not doing anything you can't do manually, and it's nice to at least do the manual approach once, so you see what's happening.

A fairly definitive paper on MS is here:

http://www.wesdooley.com/pdf/technique.pdf

As far as levels, that's important. I'd first calibrate the mic levels by placing them side by side, aimed in the same direction - so right at your guitar, not turned sideways for the side configuration. Then set them so they're the same level. Now turn the side mic. The volume of that track will decrease quite a bit, that's expected. Then if you combine them at the same gain - either manually with the faders set the same, or with something like the Voxengo free decoder with everything set at 0, you'll have the equivalent of X/Y as described in the dooley paper. If you have identical mics, you can usually just set the preamp gain controls the same, but in your case, your mics may not have the same output levels.

The width control is addicting, indeed. Like reverb, EQ, exciters, etc, once you get used to a setting you want more, then you get used to that and want more... It helps to have a reference track to keep yourself in check.

There's something really compelling about M/S for guitar, a very stable center image, along with as much spaciousness as you want, all with phase coherence.
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Old 01-15-2012, 12:20 AM
flagstaffcharli flagstaffcharli is offline
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Doug,

Thanks so much! Now I have my homework for tomorrow.
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Old 01-17-2012, 10:30 AM
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Originally Posted by Doug Young View Post

. . .

As far as levels, that's important. I'd first calibrate the mic levels by placing them side by side, aimed in the same direction - so right at your guitar, not turned sideways for the side configuration. Then set them so they're the same level. Now turn the side mic. The volume of that track will decrease quite a bit, that's expected. Then if you combine them at the same gain - either manually with the faders set the same, or with something like the Voxengo free decoder with everything set at 0, you'll have the equivalent of X/Y as described in the dooley paper. If you have identical mics, you can usually just set the preamp gain controls the same, but in your case, your mics may not have the same output levels.

. . .

Doug, could you be more specific with how to calibrate manually? Thanks.
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Old 01-17-2012, 10:38 AM
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Doug, could you be more specific with how to calibrate manually? Thanks.
Just set both mics side by side, and aim them forward (the figure 8 shouldn't be side-to-side). If your figure 8 mic has switchable patterns, you might place it in cardiod. Then play or have some sound source in front of the mics, and adjust your preamp's gain controls until both mics have the same level. Now, set up the MS arrangement, and don't change your preamp's gain.
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Old 01-17-2012, 12:21 PM
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The biggest thing to watch out for is having the overall polarity totally reverse if you mix in too much of the side signals.
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Old 01-17-2012, 12:52 PM
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The biggest thing to watch out for is having the overall polarity totally reverse if you mix in too much of the side signals.
I'm still exploring this. What I do notice is too much side signal sounds silly - like some giant, glorious guitar played by gods. I recorded a friend playing classical guitar last night, and I did a recording of one of my steel string pieces. I've been doing some comparisons with records I like. Just getting a feel for it.

The other thing I'm getting is room noise, especially from the S mic. I had them about 2 feet out. I'm going to experiment with closer mic'ing and tonight I get to move a bunch of furniture around so I can set things up with the laptop outside the room. Fortunately, my studio connects to the rest of the house via a little hallway, and my wife doesn't seem to mind if I take over a bit more space. (I'm a lucky guy. )

I'm pretty excited about this technique already. The tones we got were very nice. At the moment my biggest concern is trying to reduce the noise a bit, and I expect getting the computer and gear out of the room is going to make a big difference.
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Old 01-17-2012, 12:58 PM
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The biggest thing to watch out for is having the overall polarity totally reverse if you mix in too much of the side signals.
What do you mean in practical terms?
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Old 01-17-2012, 01:30 PM
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Quote:
Originally Posted by flagstaffcharli View Post
I'm still exploring this. What I do notice is too much side signal sounds silly - like some giant, glorious guitar played by gods. I recorded a friend playing classical guitar last night, and I did a recording of one of my steel string pieces. I've been doing some comparisons with records I like. Just getting a feel for it.

The other thing I'm getting is room noise, especially from the S mic. I had them about 2 feet out. I'm going to experiment with closer mic'ing and tonight I get to move a bunch of furniture around so I can set things up with the laptop outside the room. Fortunately, my studio connects to the rest of the house via a little hallway, and my wife doesn't seem to mind if I take over a bit more space. (I'm a lucky guy. )

I'm pretty excited about this technique already. The tones we got were very nice. At the moment my biggest concern is trying to reduce the noise a bit, and I expect getting the computer and gear out of the room is going to make a big difference.
Re: Distance - try placing the mics as far away as the length of you guitar body. It's a good starting point and often the best compromise between natural sound and overall signal to noise, at least in a quiet room.
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Old 01-17-2012, 01:40 PM
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What do you mean in practical terms?
In M/S, the 2 sides are of opposite polarity to each other. In proper proportion with the mid signal, this is an asset that gives you the stereo space but keeps the overall polarity (phase) more + than -. Too much side signal in the mix will yield more - than plus. At that point, one of your ears will be pushed while the other is being pulled - a very odd sound & more odd a sensation. When summed mono, the sound loses much of it's body and sounds like it's coming through a thin soda straw. In a mix with other instruments, you run the risk of losing the sound to a degree that it might as well not even be there at all.
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Old 01-17-2012, 01:45 PM
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Quote:
Originally Posted by flagstaffcharli View Post
I'm still exploring this. What I do notice is too much side signal sounds silly - like some giant, glorious guitar played by gods. I recorded a friend playing classical guitar last night, and I did a recording of one of my steel string pieces. I've been doing some comparisons with records I like. Just getting a feel for it.

The other thing I'm getting is room noise, especially from the S mic. I had them about 2 feet out. I'm going to experiment with closer mic'ing and tonight I get to move a bunch of furniture around so I can set things up with the laptop outside the room. Fortunately, my studio connects to the rest of the house via a little hallway, and my wife doesn't seem to mind if I take over a bit more space. (I'm a lucky guy. )

I'm pretty excited about this technique already. The tones we got were very nice. At the moment my biggest concern is trying to reduce the noise a bit, and I expect getting the computer and gear out of the room is going to make a big difference.
I believe for M-S recording of guitar you need to be close mic'd so that some of what you get in the side mic is the same as what's coming into the center (when the side signal is added to the center signal for one stereo channel, and the inverted side is added to the center siganl for the other stereo channel, there must be some 'common signal' from both mics in order to generate the stereo field).

I'd suggest close micing ( around 8"?) somewhere near the mid point of the body, but in such a way so your center mic isn't in the blast of air from the soundhole.

Here's a song I recorded with MS technique. There are 3 versions, with differing amount of stereo field created by differing amount of side signal added to the center.

http://soundcloud.com/chuck_s/sets/m...poling/s-YclT7
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Old 01-17-2012, 01:54 PM
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I believe for M-S recording of guitar you need to be close mic'd so that some of what you get in the side mic is the same as what's coming into the center [/url]
There's no reason MS micing should be any closer than, say, X/Y. That said, I tend to use it closer than Rick suggests myself - and 8 inches is about what I usually end up with as well. I usually center it inline with the soundhole, but raised around the top of the guitar so I'm not in front of the soundhole. But your result will probably vary with your acoustics. Rick probably has better luck with further out because he has better room acoustics to work with than most of us. If your acoustics allow, further out should sound more natural.
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Old 01-17-2012, 02:09 PM
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Originally Posted by ChuckS View Post
I believe for M-S recording of guitar you need to be close mic'd so that some of what you get in the side mic is the same as what's coming into the center (when the side signal is added to the center signal for one stereo channel, and the inverted side is added to the center siganl for the other stereo channel, there must be some 'common signal' from both mics in order to generate the stereo field).
Hi Chuck...
Some of my most successful uses of mid-side are with bluegrass groups and choirs - not close microphone positioning at all.

While backing out the mics does cause mid-side to pick up more of the room, it also expands the natural feel of the recordings.


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Old 01-17-2012, 02:22 PM
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There's no reason MS micing should be any closer than, say, X/Y. That said, I tend to use it closer than Rick suggests myself - and 8 inches is about what I usually end up with as well. I usually center it inline with the soundhole, but raised around the top of the guitar so I'm not in front of the soundhole. But your result will probably vary with your acoustics. Rick probably has better luck with further out because he has better room acoustics to work with than most of us. If your acoustics allow, further out should sound more natural.

I try to stay out of the guitar's "nearfield" which is where proximity effect comes into play. A distance equal to body length is right on the edge of that point. All of this goes out the window during a multi-player session when the need for separation comes into play.
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Old 01-17-2012, 02:26 PM
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Hi Chuck...
Some of my most successful uses of mid-side are with bluegrass groups and choirs - not close microphone positioning at all.

While backing out the mics does cause mid-side to pick up more of the room, it also expands the natural feel of the recordings.


Hi Larry,
I'd agree that close micing of M-S isn't required for groups/choirs as those musical source are themselves quite wide as compared to a single guitar. My comment was only meant to apply to M-S recording for a single guitar. I'll also admit my experience is much less than many other commenting here, and is partly based on theory of M-S recording and on the characteristics of a figure 8 mic as it moves away from the source.
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