Tutorial: Getting Started with Spatial Mic USB – Part 2

Tutorial: Getting Started with Spatial Mic USB – Part 2
October 1, 2019 Voyage Audio

In part 2 of this 2 part Getting Started with Spatial Mic USB tutorial series, you will learn how to use the Spatial Mic Control app and Spatial Mic Converter plugin to help dial in the perfect recordings from Spatial Mic USB. Finally, we’ll give some ideas on going further once you’ve mastered the basics.

Control Everything

The Spatial Mic Control app provides remote manipulation of various hardware parameters on Spatial Mic USB. Spatial Mic Control communicates with the microphone through the same USB cable used to supply power and stream audio data. Spatial Mic Control replicates the hardware controls found on Spatial Mic USB itself and adds additional functionality.

With Spatial Mic USB plugged into your Mac OSX or Windows host computer, simply launch Spatial Mic Control. You will see the following interface:


Spatial Mic Control provides the following functionality:

Mic Gain
Adjusts the gain of capsules before analog to digital conversion. Optimize mic gain so that the capsule signal is not clipping. Changes made to this control will be reflected in Mic Gain mode on the microphone itself.

Mix
Rotating the control to the left increases the amount of live microphone signal in the headphone mix, while rotating the knob to the right increases the amount of stereo host playback in the mix. This adjustment only affects the stereo audio signal sent to the headphone output on Spatial Mic USB. Changes made to this control will be reflected in Mix mode on the microphone itself.

Headphone Level
Adjusted level of headphone signal present on microphone HP output. Changes made to this control will be reflected in HP mode on the microphone itself.

Mute
Mutes the signal coming from microphone capsules. This button functions the same as long pressing the knob on the front of Spatial Mic USB.

Meter
Changes what is shown on the Spatial Mic USB LED display (persists when mic is power cycled). When powering up Spatial Mic, the LED display will show a turn-on sequence and then display the last metering mode selected with Spatial Mic Control. The metering modes that may be selected are:

  • Off – no metering or LEDs on
  • Monitor – LEDs display stereo L-R mix of Live binaural monitoring and host device playback.
  • Capsule (Factory Default) – LEDs display signal level for the 8 capsules. If audio from a capsule clips, it’s corresponding LED will turn red for 3 seconds. This is an indication that you may need to decrease capsule gain.

The Spatial Mic Converter Plugin

Now that we can record and control the microphone, let’s dive into the controls for the Spatial mic Converter Plugin. The Spatial Mic Converter plugin transforms the audio signals from Spatial Mic USB to a format useful for audio production. The audio output decoded from Spatial Mic Converter can be first or second order ambisonics in AmbiX or Fuma, mono or stereo virtual mics, or up to 7.1.4 surround. To accomplish this, Spatial Mic Converter uses an internal 64-channel filter matrix and measurements from an anechoic chamber.

Spatial Mic Converter offers the capability to change the microphone’s aim at the point in space where the audio was recorded. This is useful when aligning audio position with 360 video, aiming the mic at specific sounds that should be in front of the listener, or used in combination with the virtual mic output stage to focus directional polar patterns at different parts of the soundfield.

The ambisonic output can be sent to a variety of plugins from SSABlue Ripple SoundIEMSPARTA and others for further processing while mono or stereo outputs can be used with standard audio production plugins. The surround outputs can be used as sound bed tracks in Dolby Atmos® sessions or routed directly to the surround bus of choice.

The built-in Spatial Mic Converter filters are specific to the raw signals from Spatial Mic and as such are only valid for the Spatial Mic product family. Note that the plugin also offers the ability to load custom 64-channel .wav filters for any 8-channel second order microphone, however this is beyond the scope of this article. Spatial Mic Converter should be the first plugin in your signal chain when processing the raw signals from Spatial Mic.

Once Spatial Mic Converter is inserted on a track with enough channels for Second Order Ambisonics (9) you should see the following user interface:


Interface

There are 3 main sections to the Graphical User Interface.

Processing
This section displays and allows user input to change mic orientation, rotation, filter and more.

Inputs
Shows the unprocessed level with clip indication for each of the 8 capsules.

Outputs
Shows the processed output level with clip indication. Channel ordering changes based on output format selection.

Controls

Spatial Mic Converter provides the following functionality:

Mic

Select which model Spatial Mic captured the audio tracks being converted. This will load the appropriate microphone specific files in the Filters dropdown menu below.

  • Dante
  • USB/ADAT

Filter

Each microphone model has its own filters to transform the raw capsule output.

  • Spatial Mic USB/ADAT: Type 1 and Type 2 allow for a tonal choice and both have complimentary low noise versions. In general, the Type 1 filter selection will have a slightly more pronounced mid-range vs Type 2. While Type 1 and Type 2 offer the best spatial resolution, Type 1 LN and Type 2 LN conversion filters offer lower noise alternatives for recording quiet sound sources. Type X and Type Y were made in a new anechoic chamber to add to the variety of tonal options available. It is best to trust your ears and select the filter that fits your recording.
  • Spatial Mic Dante: Type A, Type B
  • Custom: There is also the option to load a custom filter (64-channel .wav expected)

Tilt
Tilts the Spatial Mic recording direction up and down. Rotation and roll are maintained when tilting.

Rotation
Rotates the Spatial Mic recording direction left and right. Tilt and roll are maintained when rotating.

Roll
Rolls the Spatial Mic recording direction side to side. Tilt and rotation are maintained when rolling.

High Pass

Activates a selectable frequency (80Hz, 120Hz, 160Hz) high pass filter, useful to cut wind noise or other low frequency artifacts.

Orientation
Match the orientation picture to the corresponding real-life position of the microphone.
Normal: The Spatial Mic capsule array is aimed up.
End-Fire: The Spatial Mic capsule array is aimed forward.
Inverted: The Spatial Mic capsule array is aimed down.

Trim
Controls input level. Plugin processing may increase the signal level. If output meters clip, you may need to reduce trim.

Outputs
Selects the output type. This should correspond to the input type of the next plugin in the signal chain. Note that the output types differ in channel count, ordering and level weighting.

Options: ambiX 2nd Order, ambiX 1st Order, FuMa 2nd Order, FuMa 1st Order, Virtual Mic, Mid-Side, and Surround.

For a more detailed look at the Spatial Mic Converter Plugin outputs see the Spatial Mic Converter Plugin Overview Tutorial.

Going Further

In this two part tutorial we have explored recording audio with Spatial Mic USB to a computer. We’ve learned how to encode (Spatial Mic Converter Plugin) and decode (IEM BinauralDecode) audio, remotely control Spatial Mic USB hardware and manipulate our audio scene with Spatial Mic Converter plugin. 

For some, this may be all that is needed before syncing 3D audio to video.

If your interest lies in using Spatial Mic USB along with other microphones, you may want to explore the possibilities of using ADAT light-pipe to connect to an audio interface. There are many hardware boxes and converters on the market from various manufacturers that will allow you to convert from ADAT to analog or other types of digital interfaces.


We encourage you to learn more about applications for Spatial Mic and Spatial Mic Converter, and invite you to try out Spatial Mic Converter for yourself with our free session downloads.


We will dive deeper into advanced microphone techniques in future articles. What would you like to read more about? Feel free to reach out on social media or by email to let us know.