Topic: Visualization of various stereo mic configurations

[DigiGal]

Here is a fun link demonstrating the various stereo mic configurations.  You can vary the mic patterns and angles in real time within any of the listed configurations and see how your coverage is affected. 

DINa is not included seems DINa is never mentioned.  Who came up with DINa?  You can visualize it, however, by selecting the DIN configuration and changing the microphone distance from 0.20 to 0.17 meters.

I've duplicated this topic including the link in the TS Knowledge Base / Archive since it makes an excellent reference.


http://www.sengpielaudio.com/Visualization-ORTF-E.htm

[ArchivalAudio]

very fun!
nice to see the additional info on arrays!

--Ian

[Gutbucket]

This is a good resource for comparing differeces in mic setups if interpreted correctly.

Grey zone  = stereo recording angle (usually different than the angle between mics)
Colored lines = spatial distribution of individual sounds from pickup to playback

The colored bars tend to attract more attention in this visualization and help to understand some of the sonic differences between setups, but the size and limit of the grey zone is probably more important in the grand scheme of choosing a configuration for a specific recording location.

Other links to this visualization have been posted here a few times over the last few years. I remember a more in depth discussion of it at one point, which might be worth a search for anyone interested.

Here's another useful one that's been posted previously where you can enter different angles, spacing, patterns, delays, etc. and get similar data but in a different fomat- http://www.hauptmikrofon.de/ima2-folder/ImageAssistant2.html

[stevetoney]

Wow, the one you posted Gutbucket totally put me into sensory overload trying to figure it out. 

I really like the first one posted though.

My only comment on that first one would be that it would have been useful to include distances as inputs rather than Orchestra Angle...or they could have had the option for calculating that angle based on distances between speakers/orchestra and distance to mics so that the program could calculate the angle.  Reason is that I can't measure an angle, but I can approximate distances.

Otherwise, it looks like a cool little tool.

[Brian Skalinder]

Reason is that I can't measure an angle, but I can approximate distances.

Approximating angles is easy:  http://taperssection.com/index.php?topic=137228.msg1784150#msg1784150

[stevetoney]

Reason is that I can't measure an angle, but I can approximate distances.

Approximating angles is easy:  http://taperssection.com/index.php?topic=137228.msg1784150#msg1784150

Nice Brian.  Thanks! 

I do remember now reading this suggestion, but had forgotten.

Wouldn't it be cool to have that somehow plugged into an iphone app where you could point the phone at the various extremes to get the angles and then enter the other info to get the SRA's in the field.  I know it can be done manually, but it would be pretty cool to have something that does it quick and easy from an electronic device.   

[DigiGal]

Reason is that I can't measure an angle, but I can approximate distances.

Approximating angles is easy:  http://taperssection.com/index.php?topic=137228.msg1784150#msg1784150

Nice Brian.  Thanks! 

I do remember now reading this suggestion, but had forgotten.

Wouldn't it be cool to have that somehow plugged into an iphone app where you could point the phone at the various extremes to get the angles and then enter the other info to get the SRA's in the field.  I know it can be done manually, but it would be pretty cool to have something that does it quick and easy from an electronic device.

You could always use an inexpesive protractor (pictured below) to get the angles right.  Alternately there are several protractor apps available for the iPod Touch/iPhone too.  It would be awesome if the original program I linked were available in a mobile app.

[Gutbucket]

The phone app thing would be sweet for those that carry a smart phone.

I've struggled with a protractor once or twice trying to sight read angles and it just didn't work for me 'off the flat page'.  Michael Williams (Stereo Zoom author) builds his own angle viewers out of a fish-eye peep-hole door lens.  I think he sells them too.  Nicely crafted beautiful wooden construction, but a bit big in pocket. http://www.mmad.info/MSS/mmss.htm  You look like a serious recordist when you pull that out!

[stevetoney]

Looks like you could also peep in on the neighbors or navigate by stars with that...or just keep it around in case Rover needs dentures.

[Gutbucket]

10 degree fist method works for me.  I have gotten a few odd looks occasionally doing it, which I usually consider a bonus.  A flowered young girl once asked as I pointed a fist towards the stage and squinted at it, "you seem so happy and mellow, what's up with that psychically punching out each of the performers thing?" 

[MIQ]

The Sengpielaudio Visualization is fun to play with.  I wanted to be able to compare a bunch of configurations for cardioid mics on the same sheet, so I drew a few up in a drafting program.  See attached PDF.  I modeled my Busman BSC1 mics and used them in the drawings for reference.  

By studying the diagrams you can get a feel for how time delay and intensity are traded to vary the recording angle.  By comparing the four configurations at the bottom of the sheet (the angle between the mics is a constant 90 degrees), you can see that increasing the distance between mics (increasing inter-channel time delay) causes the recording angle to decrease.  By comparing ORTF and DINa (the distance between the mics is a constant 17cm), you can see that decreasing the angle between the mics (decreasing inter-channel level differences) causes the recording angle to increase. 

To increase the recording angle - move the mics closer together and/or decrease the angle between them
To decrease the recording angle - move the mics further apart and/or increase the angle between them

The Shure and Schoeps guides, with diagrams similar to this, don't include DIN or DINa. It is nice to see most of the common cardioid configurations tapers use on one sheet. 

At Gutbucket:  Doesn't Williams call his contraption the "crocodile"?  I can see why...

-MIQ

[achalsey]

bump...  I've got a pair of hypers and subs coming soon so I've been playing around with this.

One question though, what does "Orchestra angle mean?"

[ScoobieKW]

bump...  I've got a pair of hypers and subs coming soon so I've been playing around with this.

One question though, what does "Orchestra angle mean?"

Orchestra angle is 1/2 the angle formed between the left of your sound source and the right of your sound source with you at the vertex. The further back you are from your sound source the smaller this angle will be. The reason it's 1/2 the angle is that Orchestra Angle is expressed as a +/-

[achalsey]

Ooohh...So the closer you get (say onstage) you might get an angle closer to +/- 50/60 depending on how far the band is spread out?

[ethan]

Sweet now I know why I like XY for onstage

[Gutbucket]

That's right, and when you input a different +/- value in the 'orchestra angle' input box, the result is visually indicated by changing the spread of the colored lines superimposed on the mic pattern display.  Those colored lines in the mic pattern display indicate the actual position of individual live sound sources on stage, within that particular orchestra angle.  Those won't move if you change other mic configuration parameters.

The other colored lines in the playback speaker display show where in the stereo image those actual sound sources will be reproduced on playback, so that set of colored lines will shift around depending on all the other mic setup parameters you enter.  The relationship between the colored lines on the speaker display and those on the mic display indicates the source image position distortions on playback  - distortions that can be good, not necessarily bad! For instance: if most of the colored lines are shown as bunched around the two speakers without many in the middle, you might expect the 'hole in the middle' situation (see footnote).  Conversely if all the lines are bunched in the center, it indicates that the playback will probably sound predominantly mono.  Play around with it and it will make sense.

footnote: Keep in mind that this colored line display is modeled after and mostly relevant for situations where the sound is coming from the actual sound sources on stage, not from speaker stacks on either side of the stage.  Think things like recording on stage, from the stage-lip or an orchestra or something without a PA.  Recording a PA reinforced band from the section where a much smaller portion of sound arrives directly from the actual instruments on stage is a very different beast.  In particular, the 'hole in the middle' condition indicated on this display may not apply if the PA is mostly mono and your recording position is pretty much centered between stacks.

[ethan]

I SO need this as a phone app.

[ScoobieKW]

I SO need this as a phone app.

HTML and Javascript, but doesn't work with the touch interface of the iPod Touch. Any iOS programmers on this board?

[ethan]

I SO need this as a phone app.

HTML and Javascript, but doesn't work with the touch interface of the iPod Touch. Any iOS programmers on this board?

I'll see how my droid does.

I'm thinking something a little different though for a phone app. You'd want the ability to visually input the orchestra angle somehow by lining up your location and the sound stage and have it come up with angle between the mics and spacing recommendations.

Edit: or better yet have some way the gyro's on the phone can be used for input. Something like point it at center then rotate left side through right side.

[ethan]

So I just noticed the CopyLeft on the page. I wonder if this means we can get the source code for this.

[ScoobieKW]

It's Javascript and HTML, the sourcecode is in the page.

If it's copyleft we should be good to go.

Steve

[DigiGal]

It would be great to see this made into an iOS App, any board members capable of doing that???

[ethan]

I don't think the accelerometers on smartphones will work for data input but perhaps the compass

[ethan]

It would be great to see this made into an iOS App, any board members capable of doing that???

Well if I were to take it on it would be android...don't have an iphone and I'd prefer writing in Java to  Objective C anyways.

First things first I've got to digest the javascript code so i can get an idea of what it does.

[ScoobieKW]

http://www.rycote.com/images/uploads/The_Stereophonic_Zoom.pdf

Michael Williams in this paper, lists the AES papers that have the math and physics behind this if you want to dig in deeper.

He also has some handy precalculated graphs in it. Been meaning to laminate these and keep them in my gear bag.

[Gutbucket]

I've posted this link at TS previously, but it should be here for this discussion-
http://www.mmad.info/MAD/Ch_n_cov.htm
^^^
Link to Michael Williams' web page accessing a large number of his mic array charts, both 2 and multi-channel.  This is a link driven configurator that gets you to a specific stereo zoom chart, depending on your desired recording angle, mic pattern, number of mics, etc.  It's missing information on 3-channel configs which I would really find useful and hasn't been further updated in a number of years, yet is an outstanding resource.

He previously had all his AES papers posted on another page at that site for anyone to download, many containing the background information on the development of the data and methodology for deriving the charts (as well as the math behind the apps were talking about) as well as additional charts not linked on the page above such as his 'Magic Arrays'.  However, I just checked and it looks like all those links have now been removed. The papers are still listed, but the reader is directed to the AES site- a pay to download provider.   Bummer.

[MIQ]

I've been working with a friend who is an iApp developer on some stereo mic apps.  As an easy first step to get some of the building blocks in place we developed a Mid-Side mic visualizer.  I know it's not exactly what we've been discussing in this thread, but it is another tool that I think many of you will find useful and fun to play with.  You can find it in the App Store by searching for "Mid-Side Mic Visualizer".  It was released on the 8th.  I've been traveling for work and didn't even know it was released until last night.   

The basic idea of the app is to allow you to see the relationship between the polar patterns of the Mid and Side mics and the resultant Left and Right polar patterns as you vary the Mid to Side signals' ratio (levels). 

We included a couple of ways to change the mid mic type.  There is a selector menu button at the bottom where you can choose from most of the standard mic types (Omni, Card, Subcard, Hyper, Fig 8, etc).  The slider on the left will also allow you to vary the polar pattern continuously from Omni to Fig 8.  At the bottom of the visualizer there is a polar plot that displays the Mid and Side mic polar patterns.  As you vary the mid mic type, the changes are displayed in this polar plot.

The other slider at the right side of the app allows you to vary the ratio of Mid to Side mic signal used in the Mid-Side matrixing.  This slider allows you to vary the levels of the signals anywhere from 100% Side to 100% Mid.  The changes to the Mid to Side relative levels are displayed in the Mid and Side polar plot at the bottom.  The polar plots of the post matrix Left and Right signals are displayed in the polar plot display at the top of the app.  It is interesting (and informative  ) to see the Left and Right polar patterns change in shape and orientation as you slide the Mid to Side ratio slider up and down.  Either of the sliders can be moved in one step increments by tapping the buttons at the top or bottom of the sliders. 

Also included is an information (geek) page where I've written a short description of the Mid-Side microphone technique and how it works.  Below are a few screen captures of what the app looks like.

I'm excited for you guys (and DigiGal  ) to check it out since I know a lot of you use Mid Side and also want iApps to play with.  Please let me know what you guys think and feel free to send me feedback about how the app can be improved or corrected.  I hope you dig it.

-Mike (aka MIQ)

[DigiGal]

I've been working with a friend who is an iApp developer on some stereo mic apps.  As an easy first step to get some of the building blocks in place we developed a Mid-Side mic visualizer.  I know it's not exactly what we've been discussing in this thread, but it is another tool that I think many of you will find useful and fun to play with.  You can find it in the App Store by searching for "Mid-Side Mic Visualizer".  It was released on the 8th.  I've been traveling for work and didn't even know it was released until last night.   

The basic idea of the app is to allow you to see the relationship between the polar patterns of the Mid and Side mics and the resultant Left and Right polar patterns as you vary the Mid to Side signals' ratio (levels). 

We included a couple of ways to change the mid mic type.  There is a selector menu button at the bottom where you can choose from most of the standard mic types (Omni, Card, Subcard, Hyper, Fig 8, etc).  The slider on the left will also allow you to vary the polar pattern continuously from Omni to Fig 8.  At the bottom of the visualizer there is a polar plot that displays the Mid and Side mic polar patterns.  As you vary the mid mic type, the changes are displayed in this polar plot.

The other slider at the right side of the app allows you to vary the ratio of Mid to Side mic signal used in the Mid-Side matrixing.  This slider allows you to vary the levels of the signals anywhere from 100% Side to 100% Mid.  The changes to the Mid to Side relative levels are displayed in the Mid and Side polar plot at the bottom.  The polar plots of the post matrix Left and Right signals are displayed in the polar plot display at the top of the app.  It is interesting (and informative  ) to see the Left and Right polar patterns change in shape and orientation as you slide the Mid to Side ratio slider up and down.  Either of the sliders can be moved in one step increments by tapping the buttons at the top or bottom of the sliders. 

Also included is an information (geek) page where I've written a short description of the Mid-Side microphone technique and how it works.  Below are a few screen captures of what the app looks like.

I'm excited for you guys (and DigiGal  ) to check it out since I know a lot of you use Mid Side and also want iApps to play with.  Please let me know what you guys think and feel free to send me feedback about how the app can be improved or corrected.  I hope you dig it.

-Mike (aka MIQ)

Great I purchased this app to give it a try.  Big suggestion though, please make it compatible with iOS version 4.2.1.  My device won't support iOS version 5.xxx so I can't actually use the app as it is now  .  I was curious if you included a shotgun pattern for the Mid too.

Hopefully, you guys can make it compatible with 4.2.1, I'm not planning on replacing my device until the next major hardware bump from Apple.

[MIQ]

Hi DigiGal,

I'm sorry you are not able to check it out even after you purchased it.     I have asked my friend how difficult it would be to make a version that is compatible with older versions of iOS.  I'll let you know what he says.  Currently it will work on iPhone 3GS, iPhone 4, iPhone 4S, iPod Touch 3rd generation, iPod Touch 4th generation, and the iPad, but you must have iOS 5.0 or higher to use it.  I know it is too late now but this is shown in the "Requirements" text in the apps store.  PM me with your address and I can send you a dollar back in the mail if you are really bummed.

We have not included a shotgun pattern for the mid mic.  As a start we concentrated on only "first order" microphone patterns.  I'll take a look at how to derive the pattern for a shotgun mic.  I imagine it may be different from manufacturer to manufacturer but I haven't explored shotgun mics at all.  Thanks for the suggestion.

-MIQ

[MIQ]

I heard from my friend (Rob) today.  He said making a version for iOS 4.2.1 is doable.  He is cranking on some other projects right now but thought that after New Years he would likely have some time.  Also, we will hopefully have some other feedback we could incorporate at that time.  Sorry for the wait.  I really wish you could use it NOW.

I've been researching how to derive shotgun polar patterns.  I've got a good start on it.  I'll see if we can get them into the app at the same time.  I'll post a pic of the shotgun pattern I'm thinking of using in a few.  I need to make sure it looks like the ones that are published for common shotguns first.


-MIQ

[DigiGal]

I heard from my friend (Rob) today.  He said making a version for iOS 4.2.1 is doable.  He is cranking on some other projects right now but thought that after New Years he would likely have some time.  Also, we will hopefully have some other feedback we could incorporate at that time.  Sorry for the wait.  I really wish you could use it NOW.

I've been researching how to derive shotgun polar patterns.  I've got a good start on it.  I'll see if we can get them into the app at the same time.  I'll post a pic of the shotgun pattern I'm thinking of using in a few.  I need to make sure it looks like the ones that are published for common shotguns first.


-MIQ

Great news thank you, looking forward to the update.  I personally will use either a AKG CK98 or Sennheiser ME66 for a shotgun mid on occasion. 

[Gutbucket]

I've been researching how to derive shotgun polar patterns.  I've got a good start on it.  I'll see if we can get them into the app at the same time.  I'll post a pic of the shotgun pattern I'm thinking of using in a few.  I need to make sure it looks like the ones that are published for common shotguns first.

Patterns between various interference tube (shotgun) mic vary greatly between models and manufacturers.  They also vary dramatically with frequency - far more than 'classic' first order microphone patterns do, even the ones that don't hold their pattern well.  I'm pretty sure all of these configuration visualizers assume a textbook pattern that is invarient over the full frequency range, which is rarely the reality of the situation, but close enough for jazz, rock'n'roll, bluegrass, classical. 

[MIQ]

Thanks Gutbucket

I noticed the freq dependency in the equation I'm using.  Also the length of the interference tube plays a big role in the response.  The thing that is most surprising to me is that the rear attenuation gets worse between 1k to 4kHz and then starts to get better above 4k on the plots from AKG and Senn.

The first order patterns we used in the Mid-Side Visualizer are assumed to be ideal and I mention that that is not reality in the info page.  I reference the paper by Trevor de Clercq here http://www.midside.com/pdf/nyu/masters_thesis.pdf  It might have been you who turned me on to that paper. 

-MIQ

[MIQ]

Attached is a first stab at a shotgun polar response.  I tried to hit the following 1kHz response points from the CK98

-5dB @ 60 deg
-20dB @ 90 deg
-15dB @ 180 deg

The ME66 is not quite as directional.  It's front lobe is almost exactly the same as a supercard but the rear lobe has more attenuation.

-MIQ

[John Willett]

Attached is a first stab at a shotgun polar response.  I tried to hit the following 1kHz response points from the CK98

-5dB @ 60 deg
-20dB @ 90 deg
-15dB @ 180 deg

The ME66 is not quite as directional.  It's front lobe is almost exactly the same as a supercard but the rear lobe has more attenuation.

-MIQ

This chart is very misleading, unfortunately.

It only shows a theoretical pattern at a single frequency which is totally meaningless for an interference tube gun mic.

A gun mic. will normally have a super-cardioid capsule, so the low frequency response will be the same as a super-cardioid.

However, it has an interference tube on the front - this will make the microphone more directional as frequency rises.

This is the polar-pattern of the MKH 60 which shows this effect very clearly:-

(low frequencies up to 1kHz are on the left and high frequencies 2kHz and above are on the right)


This is the polar-pattern of the ME 66:-

(low frequencies up to 1kHz are on the left and high frequencies 2kHz and above are on the right)

I hope this helps.

[MIQ]

Thanks John,

This is exactly what I noticed.  The low freq response is basically that of a supercard.  Thanks for confirming this since I was assuming manufacturers start with something like a supercard capsule design and then stick an interference tube on the front of it.  Is that close to true?

The response of an interference tube follows the basic formula:

R = sin(pi/wavelength)*(length of tube - length of tube*cos(theta))
      ---------------------------------------------------------------------------------
       (pi/wavelength)*(length of tube - length of tube*cos(theta))

where wavelength is the wavelength of sound and theta is the angle of the sound source (incidence).  From Olson via Eargle.

The wavelength gets tiny as freq goes up and this explains the strong changes in polar pattern as freq increases.  It also explains why the response of these mics is simply that of something like a super card at 1000Hz and below.  The interference tube has little affect at these frequencies and so the capsules response dominates.  Below is a plot showing the response of an interference tube following the formula above.   Tube length = 110mm, Frequency = 8000 Hz
It looks somewhat like the ME66 response at 8kHz.  The ME66 interference tube looks about half of its 221mm total length.

John, in your opinion, is it meaningless to try to include a "shotgun" pattern (at a single frequency) for a mid side visualizer like the one we've created?  I realize there is an even stronger affect on the polar response vs freq compared to the first order mics.  Does this make it meaningless?  I appreciate your thoughts.

-MIQ

[John Willett]

Thanks John,

This is exactly what I noticed.  The low freq response is basically that of a supercard.  Thanks for confirming this since I was assuming manufacturers start with something like a supercard capsule design and then stick an interference tube on the front of it.  Is that close to true?

In essence, yes.

The longer the tube, the more directional it gets at high frequencies.

See the MKH 60 and MKH 70 side by side:-

John, in your opinion, is it meaningless to try to include a "shotgun" pattern (at a single frequency) for a mid side visualizer like the one we've created?  I realize there is an even stronger affect on the polar response vs freq compared to the first order mics.  Does this make it meaningless?  I appreciate your thoughts.

Yes, I really *do* think showing a single frequency is meaningless.  The interference tube of a normal short gun has virtually no effect at all at 1kHz and pulls in above this.

A long gun will start working at lower frequencies and be more directional at higher frequencies.

You also need to understand the what the side lobes do.

Your diagrams *do* look very good, though, but would be better to show at different frequencies.

[F.O.Bean]

Very cool, +T

[MIQ]

Thank you John,

It does look like having a single pattern displayed is not enough info for a shotgun mic.  Displaying more than one pattern, say at 2kHz and 8kHz, at the same time could be possible but might make the diagram too busy.  There is so little space on an iPhone.  The real problem IMHO is that there is not a single set of "shotgun" patterns, even if you could display the pattern at more than one freq.  As you've shown, the length of the tube changes everything.  Having an input for freq, like a selector for 1k, 2k, 4k, 8kHz etc could be possible and another for tube length in mm would be neat to play with.  But these are more complicated to implement.  To be honest we haven't seen much interest in the visualizer as it stands.  It's hard to justify sinking more time into it.

-MIQ

[Javier Cinakowski]

Is there anyway to look at thisis on a computer ir android? Id pay a lot more than $1 for an android or windows app...

[MIQ]

Hi Javier,

The visualizer was first developed as an Excel sheet to work out the algorithms and prove the concept.  The polar plots with a white background I've been posting here have been cut and pasted from that sheet.  While it's a way to see it on a computer, it is hardly a commercial product and not protected in any way. 

-MIQ

[DigiGal]

I heard from my friend (Rob) today.  He said making a version for iOS 4.2.1 is doable.  He is cranking on some other projects right now but thought that after New Years he would likely have some time.  Also, we will hopefully have some other feedback we could incorporate at that time.  Sorry for the wait.  I really wish you could use it NOW.

I've been researching how to derive shotgun polar patterns.  I've got a good start on it.  I'll see if we can get them into the app at the same time.  I'll post a pic of the shotgun pattern I'm thinking of using in a few.  I need to make sure it looks like the ones that are published for common shotguns first.


-MIQ

Do you know if he has been able to start work on making this compatible with iOS 4.2.1 yet?

[MIQ]

Hi DigiGal,

We talked about it after Xmas but I was working at CES and Rob is at NAMM so not much progress has been made.  Fortunately the update should not be too difficult.  I will keep you posted.

MIQ

[DigiGal]

Hi DigiGal,

We talked about it after Xmas but I was working at CES and Rob is at NAMM so not much progress has been made.  Fortunately the update should not be too difficult.  I will keep you posted.

MIQ

I see a new version available today is now compatible with iOS 3.2+.  For some reason it won't load on my iOS 4.2.1 device.

[MIQ]

DigiGal,

Unfortunatley the app is not supported on generation 2 devices even if they are running iOS3.2 or higher. 

If you upgrade to a gen 3 or higher device, the app will work for you.  We look forward to hearing your comments when you upgrade.   

-MIQ

[MIQ]

One thing worth noting is the new version includes a display for the Recording Angle.  The new layout look like this:

-MIQ

[DigiGal]

I'm finally able to use this with a new iOS device. Noticed a bug in iOS 6, once a mid mic is selected from the list the mid mic indicator on the visualizer screen always displays omni no matter what pattern is selected. A feature suggestion for the next update - double tapping the sliders to center them.

It's a nice app, glad to be able to use it now.

Now if someone could port the stereo mic confiuration visualizer to an iOS app.

[MIQ]

I'm finally able to use this with a new iOS device. Noticed a bug in iOS 6...

It's a nice app, glad to be able to use it now.

DigiGal, 

Really glad you are able to use it finally.  We will check out the bug you mentioned and get it sorted out.  Thank you for the heads up. 

Now if someone could port the stereo mic confiuration visualizer to an iOS app.

Ok, here you go.  Our Stereo Mic Tools app just released to day 
https://itunes.apple.com/us/app/stereo-mic-tools/id572383335?mt=8

It has 8 Mic Types from Omni to Fig-8.  The angle between mics can be varied from 0 to 180 deg.  The separation between the mics can vary from 0 to 200cm.  It has six classic configurations stored as presets:

Blumlein
DIN
DINa
NOS
ORTF
XY 90

It displays the Recording Angle and the Wittek - Thiele Recording Angle 75% (RA_75%).  And of course has a geeked out info page.   Here are some screen shots.

-MIQ

[John Willett]

Interesting - but why does it say that ORTF is +/- 48° and not +/- 55° ?

And it would be very much more useful if it included MS as well.

[Gutbucket]

Interesting - but why does it say that ORTF is +/- 48° and not +/- 55° ?

And it would be very much more useful if it included MS as well.

The SRA for ORTF is +/- 48°.

John is aware of what that means, but for anyone reading this who is not I'll explain-
With an ORTF arrangement, the physical angle between cardioid pattern microphones is specified as +/- 55° (indicated below the image on the angle button) which combined with the 17cm spacing results in a Stereo Recording Angle of +/- 48° (which is the angle of pickup for which sources are reproduced between two speakers arranged in a standard +/- 30° playback triangle, sources outside that SRA will tend to emanate from the closer speaker).

[edit] the Sengpiel site explains this better than I can, and allows one to play around with various microphone angles, spacings and pickup patterns in their on-line visualizer.
http://www.sengpielaudio.com/Fragen08.htm

from that site-
The Stereo Recording Angle SRA:
The SRA is not the angle between the microphone axes, but an invisible angle, that gives you information about your stereo image. It tells you how "wide" the recording will sound. Every acoustic sources that are outside of the SRA will be located full at "L" or "R". So a smaller SRA will give you a wider stereo image. Everything inside of the SRA will find a place between the left and the right speaker.

[MIQ]

Interesting - but why does it say that ORTF is +/- 48° and not +/- 55° ?

And it would be very much more useful if it included MS as well.

Hi John,

As Gut mentioned this app is reporting the Recording Angle and RA_75% in +/- degrees.  The angle between mics is shown as well (see the button labeled "Mic Angle"), and for ORTF is correctly shown as 110 degrees.  If you are interested in an MS visualizer please use our Mis Side Mic App.  https://itunes.apple.com/us/app/mid-side-mic-visualizer/id486145346?mt=8

-MIQ

[DigiGal]

I'm finally able to use this with a new iOS device. Noticed a bug in iOS 6...

It's a nice app, glad to be able to use it now.

DigiGal, 

Really glad you are able to use it finally.  We will check out the bug you mentioned and get it sorted out.  Thank you for the heads up. 

Now if someone could port the stereo mic confiuration visualizer to an iOS app.

Ok, here you go.  Our Stereo Mic Tools app just released to day 
https://itunes.apple.com/us/app/stereo-mic-tools/id572383335?mt=8

It has 8 Mic Types from Omni to Fig-8.  The angle between mics can be varied from 0 to 180 deg.  The separation between the mics can vary from 0 to 200cm.  It has six classic configurations stored as presets:

Blumlein
DIN
DINa
NOS
ORTF
XY 90

It displays the Recording Angle and the Wittek - Thiele Recording Angle 75% (RA_75%).  And of course has a geeked out info page.   Here are some screen shots.

-MIQ

Great timing on the new app, grabbed it right away, had been hoping someone would do this for a while now. 
Both are fabulous apps for our community.  Much appreciated, great job guys !!!   

Edit to add:
Extra credit for including DINa

[John Willett]

Interesting - but why does it say that ORTF is +/- 48° and not +/- 55° ?

And it would be very much more useful if it included MS as well.

The SRA for ORTF is +/- 48°.

John is aware of what that means, but for anyone reading this who is not I'll explain-
With an ORTF arrangement, the physical angle between cardioid pattern microphones is specified as +/- 55° (indicated below the image on the angle button) which combined with the 17cm spacing results in a Stereo Recording Angle of +/- 48° (which is the angle of pickup for which sources are reproduced between two speakers arranged in a standard +/- 30° playback triangle, sources outside that SRA will tend to emanate from the closer speaker).

[edit] the Sengpiel site explains this better than I can, and allows one to play around with various microphone angles, spacings and pickup patterns in their on-line visualizer.
http://www.sengpielaudio.com/Fragen08.htm

from that site-
The Stereo Recording Angle SRA:
The SRA is not the angle between the microphone axes, but an invisible angle, that gives you information about your stereo image. It tells you how "wide" the recording will sound. Every acoustic sources that are outside of the SRA will be located full at "L" or "R". So a smaller SRA will give you a wider stereo image. Everything inside of the SRA will find a place between the left and the right speaker.

Thanks GB - I only had a quick look and missed that.

Well, they seem cheap enough at only £5 for the two, so I now have them both.

John

[Gutbucket]

Seems useful and the price is right.  If I was an I-phone user I'm probably try them out.

[MIQ]

Thanks DigiGal, John, and Gutbucket!  We appreciate the positive feedback.

I want to mention one thing that may not be obvious unless you have the apps on your device.  If you hold your phone (or Pad, or iTouch) running the apps above your mics with the screen pointing straight up to the sky, you can sight down the Recording angle lines and see how the recording angle relates to the performers (or sound sources) in front of the mics.  You have to hold the phone still and move your head to sight down each line but it gives a quick approximation.  There are better ways to implement this with the device (think camera and gyros) but that will require considerably more effort.  We hope to be able to work more on these apps but I wanted to mention the simple method for now. 

-MIQ

[noahbickart]

I love the m/s app, and use it all the time.

Now all i want is an AU plugin that allows me to vary the relative M and S gain proportionally with the same interface.

If you could make a double m/s plugin so that someone running 2 figure 8's and an omni could select polar pattern and angle, that would be really good.

(I know about the schoeps double m/s plugin. It has two problems. One it is VST only. Also the model assumes that you are using a pair of mk4v microphones for the M signal and not an mk8 and mk2 [or in my case a mk3]).

[MIQ]

Hi Noah

Glad you continue to get good use from the M/S tool. 

Double M/S using 2 Fig-8s and and Omni is interesting.  By varying the ratio of Fig-8 to Fig-8 you can steer the angle between the resultant L and R patterns, and by combining them with the Omni you can control the patterns shapes, right?  That's cool. 

I wish we knew more about writing AU code for you.    

-MIQ

[John Willett]

Double M/S using 2 Fig-8s and and Omni is interesting.  By varying the ratio of Fig-8 to Fig-8 you can steer the angle between the resultant L and R patterns, and by combining them with the Omni you can control the patterns shapes, right?  That's cool. 

This is basically the same as a Soundfield mic. without the height information.

[noahbickart]

Hi Noah

Glad you continue to get good use from the M/S tool. 

Double M/S using 2 Fig-8s and and Omni is interesting.  By varying the ratio of Fig-8 to Fig-8 you can steer the angle between the resultant L and R patterns, and by combining them with the Omni you can control the patterns shapes, right?  That's cool. 

I wish we knew more about writing AU code for you.    

-MIQ

Yup. You could always do a real 5.1 mix as well: put a variable lpf on the omni for the subwoofer channel, and create a separate rear channel pair for the surrounds.

Yes, I wish you could code AU for me! Know anyone who can?

[MIQ]

Yes, I wish you could code AU for me! Know anyone who can?

Sorry Noah, I don't. 

[MIQ]

We are getting ready to release a new version of Stereo Mic Tools.  We've added some new tools to help get your mics configured to match the recording situation. 

The first is a "Performers Angle Viewer" for measuring the angle of the performers in front of your mics and comparing it to the Recording Angle created by your mic configuration.  We're considering the following explanation in the info page:

Performers Angle Viewer

• Start by pointing the center of the viewer at the middle of the performers and pressing the zero button to set the angle readout to zero degrees.
  
  Holding the camera level, rotate your device from the center to each edge of the performers, noting the angle at the far ends of the performers.  This is the Performers Angle.
  
  Quickly compare the Performers Angle to the Recording Angle of the current microphone configuration by noting when the angle indicated at the center of the viewer equals the Recording Angle shown in red at the bottom of the screen.  The center line and angle display of the viewer will turn red and become thicker when pointed at an angle equal to the Recording Angle.  Any performers at an angle greater than the Recording Angle will appear to come directly from the speaker on that side of the stereo playback sound system.  Performers within the Recording Angle will be distributed between the speakers of the playback system. 
  
  The RA_75% Angle is also indicated in the viewer by the center line turning green and becoming thicker when the viewer is pointed at an angle equal to the RA_75% Angle.  Keep in mind that in many cases the performers located at angles between the RA_75% Angle and the Recording Angle may not be accurately positioned by the playback sound system.

 

Here's a pic simulating an on stage application where the guitar amp is very close to the RA_75% angle.

[MIQ]

The second tool is a Mic Angle Bombsight that allows you to measure the angle between your mics. 

Microphone Angle Bombsight

• Point the bombsight down at your mics while standing directly over your mics. 
  
  Carefully hold your device flat over the mics to make sure the angle you are reading is accurate.  You can check how flat your device is by using the bubble level at the vertex of the angle lines.  Try to keep the solid black bubble within the small center ring.   
  
  The vertex of the angle lines should be directly above the vertex formed by the mic bodies and the angle lines should be parallel with the mics bodies. 
  
  The Mic Angle is displayed in blue at the top of the screen. 
  
  The center line of the bombsight should point directly at the center of the performers.
  
  The angle between a coincident microphone pair can be measured by flipping the display of the device over and placing the bubble level directly over the point where the microphone capsules overlap.
  
  The microphone angle lines can also be dragged to match the angle of the microphones.  Use your finger to drag either angle line and the other line will automatically move along with it. 
  
  The microphone angle used by the Recording Angle Calculator is updated when dragging the angle lines. The new Recording Angle and RA_75% Angle are displayed at the bottom of the bombsight screen as well as in the Recording Angle Calculator. 
  
  In some situations you may be starting your set up by pointing the mics at the venue loudspeakers ("Point at Stacks" - PAS).  By dragging the angle lines to match the microphone angle you have also determined the needed Recording Angle.  The desired +/- Recording Angle is equal to half the Mic Angle.  You can quickly determine the correct microphone spacing by switching to the Recording Angle Calculator and adjusting the Mic Separation so the calculated +/- Recording Angle is equal to half of the Mic Angle.  For example, if the mic angle between a pair of cardioid mics is 110 degrees, the distance between the microphones should be adjusted to 12 cm.  This configuration has a Mic Angle of 110 degrees and a Recording Angle of +/-55 degrees. 

We are considering adding the Mic Separation display to this screen since it is the other aspect of the mic configuration you are adjusting when you are setting their angle.  Here are some pics of the Mic Angle Bombsight in action.  Dig my fuzzy slipper:

[MIQ]

We updated the Recording Angle Calculator with a new layout.  We also added a new preset: AB50 as a starting point for spaced Omni set ups.  Same old Info text:

Recording Angle Calculator

• Preset - Choose one of the following well known microphone configurations: Blumlein, DIN, DINa, NOS, ORTF, XY90, or AB50
  
  Or, independently set...
  
  Mic Pattern - Choose the type of microphone you are using.  Eight pickup patterns from Omni to Figure 8 are available.
  
  Mic Angle - Set this to the angle formed between the bodies of the microphones.  Values from 0 to 180 degrees are possible.
  
  Mic Separation - Set this to the distance between the centers of the microphone capsules.  Coincident microphone techniques use a value of 0 cm.  Separations from 0 to 200 cm can be used.
  
  ...and observe the resultant effect on:
   
  Recording Angle - The Recording Angle is the angle in front of the mics that encompasses the angle of sound sources (performers) that will appear between the speakers when played back.
  
  Recording Angle 75% (RA_75%) - The angle in front of the mics that encompasses the angle of sound sources (performers) that will be accurately and proportionately placed within 75% of the area between the speakers similar to the way the sound sources are arranged in front of the microphones.

Here's a look at the new layout.

[MIQ]

You can see that there are new buttons at the bottom of all the screens that allow you to switch between the different screens/tools and access the info page. 

Please let us know if you see something whack  or want to comment on how it works. 

If it looks OK we'll send it off to approval soon. 

-MIQ

[DigiGal]

Nice looking updates, are they formatted to utilize the extra screen space of the current devices?

[MIQ]

...are they formatted to utilize the extra screen space of the current devices?

Hi DigiGal,

Yes, all the updated versions of our mic apps scale themselves to the screen they are running on, including the new devices.

-Miq

[MIQ]

DigiGal,

Here are some screenshots of the app displayed on the new 4 inch Retina display.  We added the Mic Separation display to the Bombsight view. 

I think (hope) people will find the new tools pretty useful.  Using capabilities built into the device, we wanted to address the complexity in determining the necessary coverage angle (Performers Angle) and the difficulty in accurately measuring the Mic Angle. 

The Performers Angle Viewer is pretty easy to use but really hard to show with a photo.  As you rotate the camera, the angle from center stage to stage L and to stage R is displayed at the top.

The Bombsight is a little trickier to use since you want the device flat (bubble level in the middle) as well as having the camera directly over the vertex of the mics and simultaneously rotating the camera so the angle measuring lines align with your mics.  It takes a little practice but it isn't a big deal after you've tried it a few times.  If someone wants to be anal retentive they can rig up a device mount to hold it in the right spot above the mics, but you can get decent measurements with a steady hand.

The updated Stereo Mic Tools and a less intense update to Mid Side Visualizer are at Apple waiting for review.  We're looking forward to hearing what you think when you get a chance to play with them. 
 
-MIQ

[DigiGal]

Anxiously awaiting the updates, how long doe the apple review process take?  Thanks for the ongoing app development.

[MIQ]

The review processes is about a week but it varies.  It's always a surprise, even for the developers.

[MIQ]

Surprise!!  They released tonight. 

–MIQ

[DigiGal]

Surprise!!  They released tonight. 

–MIQ

LIVE and direct from Network 23, err Apple App Store!  Got the updates this morning perfect timing for an orchestra recording this weekend, thanks.   

[MIQ]

Great DigiGal!  We hope they come in handy at the show.  Please let us know what you think after using them.

-MIQ

[asobriquet]

This looks good.........
Thanks.