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Re: mic arrays and M/S behaviour

Subject: Re: mic arrays and M/S behaviour
From: "lecarmo" lecarmo
Date: Wed Sep 1, 2010 10:41 am ((PDT))
--- In  Rob Danielson <> wrote:
>
> At 12:27 AM -0700 9/1/10, Luiz do Carmo wrote:
> >  Back to Back Crown SASS seemed to be a good
> >idea, at least in theory. And it could be
> >mounted with the AT4022, considering it looks
> >DIY friendly.
>
> SYou can start with Andrew's and Paul's test in
> the DIY Boundary Mics blog and go through posts
> chronologically to get some ideas:
> http://tinyurl.com/29mgcj6

I've been there and my first impression is that boundaries would lead to le=
ss interpolation, what is crucial for Dolby Analog (SR), which is the syste=
m that is (still) used in most theaters in Brazil. I'd guess that for movie=
 theaters angled setups (from about 60 to 90 degrees) should work well for =
LR and from there up to 180 should be fine in the surround. Just a guess, t=
hough.

> >I still couldn't get rid of my doubt, which
> >concerns the cardioid mics that play
> >the mids in a M/S array. Do they actually 'sound' or only work as a tool=
 to
> >separate (or design) the L and R channels? Because if they do not take p=
art on
> >the overall sound after decoding,
>
> Because using phase difference to to encode
> "Left" and "Right" seems like a simplification?
> Not really, the sound waves are striking both
> sides of the figure 8 capsule and all stereo
> relies on the brain discerning left-right
> differences. Most listeners find M-S stereo
> imagery very satisfying.

I don't expect to simplify here -- although I don't crave for complexity. A=
nd I'm sure it's not simpler, having in mind the matrix effort in post. One=
 of my interests in M/S arrays is the capability of this type of setup to b=
ecome lighter, thus more agile, and versatile, principally for documentarie=
s. The M/S results are great, but I would like to know which mic capsules w=
ould be involved in the final mixed sound.

> I can post some Perp2Sphere, SASS- B and Parallel
> Boundary imagery from the same location to
> experiment with. There are some samples you can
> access through the Community FAQ
> http://tinyurl.com/2bqxh2w  (Folks can add other
> links that Luiz can use or email them to me and
> I'll be happy to add them.)

I've collected a few links that I'll paste next.

> >I could have a pair of MKH-416 or even the way
> >less expensive NTG-3, with a NT2-A in the
> >middle. Does it sound completely nonesense?
>
> Nothing that sounds good is nonsense. :-) The
> only qualification might be on-going interest and
> awareness of what stereo and surround imagery is
> capable of. Mics/arrays/positioning is what we
> do, right?

As I said, I'm concerned about the sound quality (low self noise/clarity/co=
lour) of the capsules used in the recording -- taking into account the budg=
et. The doubt is whether the mid mics sum up to the sound or just trim the =
center, 'shaping' the stereo image. I understand, though, that by trimming =
the mid mic do interfere in the color of the stereo audio.


> >About the recorder, I followed the thread
> >discussing the DR-680 and got worried
> >about the reliability of the software, as far as
> >an issue concerning files that
> >'simply disappear'. In a feature film it could
> >lead to murder. But I didn't give
> >up on this machine. I had this recorder already in mind since its releas=
e.
>
> I've owned a number of digital recorders that
> have preferred ways to be "managed."  Once I
> figured out what they were, the recorder became
> very reliable for me to use. Sufficient powering
> is the #1 field concern no matter what recorder
> is used. Based on the whole of the reports I've
> read about the DR-680, I think one can use it
> reliably. There are some very accomplished sound
> for film recordists on this list and some may
> have had a DR680 out in the field. Perhaps look
> through the
> 
> list? http://tinyurl.com/2ewvbm6  Let us know if
> you discover chronic issues.

I haven't visited that list yet, but the problem I've mentioned was describ=
ed here: http://tech.groups.yahoo.com/group/naturerecordists/message/42000

> >The R-44 looks a little flimsy, but what got me
> >not so much excited about it was
> >the way it saves the tracks, stocking every single take in a different f=
older.
> >It wouldn't be a big hassle for ambience recording, but for a film set w=
here I
> >record 100 plus tracks in a day it could drive
> >me crazy - either to playback or
> >during post.
> >
> >I've also thought about a setup with an interface + laptop - mostly for =
the
> >small issues regarding the DR-680 and the R-44 -, but the noisy pres on =
the
> >M-Audio Fast Track Ultra were not compelling.
>
> Oh, boy. Having done this for two years, I would
> definitely advise against it. The list of
> possible problems that can crop up is much
> longer. I can see how some people could make an
> enjoyable ritual out of booting-up in the woods
> but it felt too tenuous to me.
>
> Recording longevity is becoming more of a factor
> to look at. I love that I can put a 300GB drive
> in my 744T and even record to an external drive.
> I also love being able to record in .flac.


A 744T plus a handful of MKH's would be heaven, but at the moment I've got =
to find my eden somehow differentely. ;D


> >Then I heard here about the Motu
> >Traveler-mk3, took a look at it and was impressed with the quality of th=
e
> >preamps - allegedly great, at least for the reviewers.
>
> The pres in the first Travelers models had pretty
> low gain. Not sure about the newer ones.

I'm inclined not to deal with a mechanical hd while climbing and perhaps sl=
iding around.

> >I believe that I'm researching on mic arrays first, because I'm maybe wa=
iting
> >for the release of an FR'4'-LE, which would be the best thing to happen =
for my
> >budget/expectations.
>
> The DR680 will remain one of the top bargains for a while I'd guess. Rob =
D.

You already had put the DR-680 back to my wish list.

Best,
Luiz

PS: Some few sites I've been digging into:

Rob Danielson's Pantherfile (lots and lots of things to search at)
https://pantherfile.uwm.edu/type/www/audio-art-tech-gallery/

Rob Danielson's fieldpost: Four Stereo Mic Arrays Compared - Take the blind=
 test (pink noise extravaganza!)
http://fieldpost.blogspot.com/

DIY Stereo Boundary Mic Rigs (lots of stuff)
http://diystereoboundarymics.blogspot.com/

Gary Pillon mod on SASS MKII plus... (rig)
http://www.crownaudio.com/kb/entry/200/

Frogrecordist's Modified SASS Microphone using MKH-20's, MKH-110's, AT3032'=
s et al (various samples)
http://frogrecordist.home.mindspring.com/docs/modsass.html

Frogrecordist's Mid-Side Stereo Setups (rig)
http://frogrecordist.home.mindspring.com/docs/mssetups.html

Frogrecordist's Microphone Sound Samples
http://frogrecordist.home.mindspring.com/docs/samples.html

Paul Segar and Francis Rumsey: Optimisation and Subjective Assessment of Su=
rround Sound (pdf)

Microphone Arrays (paper)
http://epubs.surrey.ac.uk/534/1/fulltext.pdf


> >I'll keep on researching and thanks again for the help.
> >
> >Luiz
> >
> >________________________________
> >From: Rob Danielson <<type%40uwm.edu>>
> >To:
> ><naturerecordists%40yahoogroups.com>=
com
> >Sent: Tue, August 31, 2010 6:46:29 AM
> >Subject: Re: [Nature Recordists] mic arrays and M/S behaviour
> >
> >At 10:51 PM -0700 8/30/10, Luiz do Carmo wrote:
> >>
> >>Hi,
> >>
> >>I am a sound professional based in Brazil. At
> >>the moment I am working in a film
> >>in which the action takes place in a rural environment surrounded by a =
dense
> >>forest. The easy way to work around our low budget enterprise would be =
the
> >>utilization of some (quite some=B7) stereo ambience recordings I have c=
ollected
> >>over the years, but I lost all of them in a
> >>`computer accident=A9=96 =B0=A9 which is a
> >>story longer than what I believe would suit the present occasion.
> >>
> >>The good part of this tragic story is that it forced me to do something=
 I was
> >>procrastinating for quite a while, since I have being inclined to start
> >>producing 4 channel recordings for such purpose,
> >>but the lack of available time
> >>and money kept delaying my plans.
> >>
> >>After gathering (googled) information around and lately here in this li=
st I
> >>ended up with two types of mic arrays that I suppose would work fine in=
 a 5.1
> >>Dolby Digital final mix, which requires discrete channels: An IRT Cross=
 or a
> >>Double M/S.
> >>
> >>To fit my budget, 4 AT4021 mics in an IRT Cross setup would do it. The =
only
> >>problem in using the ATs would be the fact that
> >>these mics would only be useful
> >>=B0=A9 for the kind of work I do: post production
> >>and location sound =B0=A9 for ambience
> >>recordings (I have Oktava MK-012s for sfx), as they are not suited for
> >>production sound/dialogues, which are almost always recorded with shotg=
uns,
> >>principally in outdoors situations.
> >>
> >>My first question is: Do the sound of the mid
> >>mics on a Double M/S take part in
> >>the overall sound, or the resulting 4 channels
> >>only carry the audio information
> >>captured by the figure-8?
> >>
> >>I ask that because if the sound of the figure-8
> >>mic is what actually is heard in
> >>the 4 channel image, I could use whatever cardioids or supercardioid =
=B0=A9 for
> >>example, a MKH-416 or a pair of Oktava MK-012,
> >>which I already have =B0=A9 without
> >>altering the quality of the figure-8 mic. I could add to this that with=
 such
> >>setup I could have a mic array already set for directional plus surroun=
d
> >>recording, which would suit perfectly for
> >>documentary film situations, besides
> >>the adition of easiness represented by a lot less gear to carry around.
> >>
> >>(The second question is about recorders and I rather leave it for anoth=
er
> >>thread).
> >>
> >>I would like to thank all the list members for sharing your knowledge, =
which
> >>already helped me a lot and specially, for the
> >>present matter, Rob Danielson for
> >>his microphone chart.
> >>
> >>Regards,
> >>Luis
> >
> >Hi Luis -
> >A belated welcome to the list! Sorry to read about your lost recordings.
> >
> >If only there was a web site with controlled
> >recordings where you could compare the impacts of
> >a number of surround array options! Without
> >samples, there are many opinions and different
> >goals to wade through without reference. It would
> >be well worth your time to find and listen to
> >actual recordings made in settings similar to
> >those you record in. To aid partially in this, I
> >can suggest a small work-sharing group that
> >focuses on surround recording. You can ask the
> >people in this group for links to samples. One of
> >the recordists uses a surround array that is a
> >variation of an IRT Cross. (Anyone who wishes to
> >have their email address added, contact me, off
> >list.)
> >
> >As you are on a tighter budget, I would
> >definitely look for field samples made with these
> >array types:
> >
> >Double M-S Arrays
> >Back to Back SASS-B Arrays (People are making DIY SASS-B's and variation=
s)
> >Spaced Rear Arrays (usually a stereo array in
> >front with wide spaced omni's in the rear)
> >Spaced Front & Back Arrays (Usually two stereo
> >arrays spaced according to habitat(s) and
> >acoustics)
> >Decca Tree (Greg Weddig comes to mind)
> >Holophone (possibly not too hard to DIY)
> >
> >Harder to DIY arrays:
> >Ambisonic Arrays
> >Sphere Arrays (Double-MS on a sphere boundary
> >like SchoepsKFM 360 or two stereo spheres back
> >to back to with a sound-blocking panel in between)
> >
> >I would not base opinion only on recording
> >samples that were made inside or of loud subjects
> >. If the "natural ambiences" you want to capture
> >become very "quiet" at times, you will want to
> >only use very low-noise mics.
> >
> >As for your recorder question, "Tascam DR680" is
> >one answer to investigate. Rob D.
> >
> >--
> >
> >
> >
>
>
> --
>
>
>








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