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Old 18th December 2018
Gear Maniac
Simmosonic's Avatar

Originally Posted by studer58 View Post
I wonder if you'd be kind enough to guide me through the section where the phone's camera is used to assess the width angle that the ensemble occupies on stage (directly in front of the mic pair), and this is then used to inform mic spacing and width to ensure congruence of stereo recording angle (SRA) ?
I use it a fair bit. Here’s what I know about it and how I use it.

Start by holding up the device so it is as vertical as possible. There should be a blue vertical line through the centre of the screen. An angle will be displayed next to it, in the upper part of the screen just to the right of the line. It could be any angle at this point in time but it needs to be 0°. It is zeroed by pressing the ‘zero’ button in the upper right of the screen. It’s not really a button, it’s just the word ‘zero’ written in relatively small blue letters, and it can be impossible to see depending on what image the camera is showing.

After tapping on the word ‘zero’, the angle displayed next to the vertical line will read 0°. Now simply turn the device on the axis created by the vertical line and it will show how many degrees you have rotated to the left or right so you can judge the width of the ensemble from the device’s point of view. As you rotate it, at a certain angle in the rotation the vertical line will turn green and also gets a bit thicker. This is the point in the camera image that will represent 75% of the stereo width. If you keep going past that point the line turns blue again until you reach the 100% width point, after which the line turns red. Anything in the area where the line is red will be hard left or right (depending on which way you’re turning!).

The 75% and 100% marker angles are based on whichever microphone width, spacing and polar response you have chosen - and those angles are shown at the bottom of the screen. As far as I know, the Performer Angle section cannot set those factors for you. So it’s a matter of back and forth stuff.

Here’s an approach I’ve taken lately where I’m using a matched pair of MKH800s on a stereo bar and don’t have a lot of time.

I start by putting the two microphones side by side, pretty much next to each other, facing foward, and in whichever polar response I think is going to be most appropriate based on surrounding sounds, etc. Monitoring through my Etymotic ER4 canal phones (excellent isolation) plugged into my Nagra 7 (which is hanging over my shoulder and connected to the mics), I move the stand around like a selfie stick (up/down/back/forth) until I find an appropriate balance of direct-to-reverberant energy and also a decent sense of ensemble. That lets me find a good starting distance and height - because you need those two things sorted before the app can make any sense.

With the distance and height sorted (close enough to start with), I’ll whip out the app and go to the Performers Angle section so I can see the angles where I want the 75% and 100% points to be - from the microphone’s distance. Then I find a combination of microphone angle, spacing and polar response to give me the required angles. After that, I’ll use the Bombsight section to set the microphone angles appropriately.

There are zillions of possibilities of spacing, polar responses and angles that will give the desired 75% and 100% angles, of course, so the choice always includes considering extraneous sounds (I’m not always in concert halls), how much mono compatibility I’ll need and so on.