Using UMIK-1 with Amarra Symphony - Quick-start guide

Using UMIK-1 with Amarra Symphony: Quick-start guide

Amarra Symphony with IRC is an advanced music file player for the Apple Mac platform. It includes a feature called "Impulse Response Correction" (IRC), that corrects for acoustical errors at the listening position caused by early reflections from the speaker and listening room. It also provides the ability to tailor the response at the listening position using target curves.

The UMIK-1 is an ideal low-cost way to perform the acoustic measurements necessary for Amarra Symphony with IRC. In this app note we'll show you how to do this. We will assume that you already have Amarra Symphony configured to play music files through your stereo system.

What you will need

  • Amarra Symphony with IRC. The Amarra Symphony with IRC installation includes a program called IRC Measure, which performs acoustic measurements and filter calculations.
  • A miniDSP UMIK-1. After receiving the UMIK-1, go to the UMIK-1 page to get the calibration file for your unique serial number, and save it as a .TXT file.
  • A microphone stand with boom arm, available in music supply outlets. (While the UMIK-1 is supplied with a small "table top" stand, the IRC Measure program requires that the microphone be positioned in several locations around the listening area).

1. Getting set up

You will need to already have Amarra Symphony playing music files from your Mac through your audio system. Typically, this will be via a USB DAC, a USB-SPDIF convertor and a DAC, or the Mac's optical digital output into a DAC.

On the input side, the UMIK-1 can be simply connected to any available USB port on your Mac. Position the computer and stand so that the mic can be moved into several positions, as will be seen in the IRC Measure interface (below).

UMIK-1 connection for Amarra Symphony with IRC

2. Configure IRC Measure

Double-click on the IRC Measure application to run it. (It is located in the /Applications/Amarra Symphony folder.) On the left are five clickable icons that select different tabs for configuring, measurement, and filter generation:

IRC Measure home screen

First, select the output device that you will be using from the Sound System Sonic tab:

Select output device

On the Mic config tab, select the UMIK-1. Click on the Load File button and locate the unique microphone calibration file that you downloaded from the UMIK-1 webpage.

Configure microphone

3. Set levels

On the Output and levels tab, set the output volume to low. Click on the Test button for the left channel and gradually increase the output volume until it is at a moderate level, such that your voice would have to be raised to converse with someone sitting next to you.

Now increase the input volume so that the blue level bar is about near the bottom of the green section of the level meter for the left channel. With the UMIK-1, you will probably need to set the input volume at maximum - this is normal. The level can be a little lower than the green bar, but if it is too low, IRC Measure will issue a warning when running a measurement. In that case, you will need to increase the output level.

Levels adjustment

Repeat the test signal for the right channel. The level should be correct without any further adjustment needed.

4. Run the measurements

You are now ready to run the acoustic measurements! IRC Measure uses nine measurements spread around the listening position to calculate its correction filters.

On the Measurements tab, select the most appropriate listening setup for you (chair, sofa, or auditorium). Position the microphone at the location indicated by the arrow. Be sure to check both the top and front views using the selector underneath the graph, so that you have the height of the microphone correct.

Then click on the Start button. IRC Measure will run three measurement sweeps, through the left speaker, then right, then left again, and display the measurement result as a plot.

Measurement tab

If there are errors in the measurement, such as clipping or low levels, IRC Measure will warn you and you will need to go back to the Output and levels tab to make adjustments. If all is well, IRC Measure will ask you to move the microphone to the next location, after which you can press Start again run another measurement. Proceed methodically through all nine measurements.

Measurements completed

At this point, you should save your project by clicking on the Save... button.

5. Generate correction filters

On the Filter Design tab, you will initially see the average of the measurements for the left and right channels. You can also opt to display all individual measurements, which shows just how much variation there is across your listening area!


Measured in-room response

Also displayed is a target curve. This is the desired in-room frequency response after correction. Typically, target curves have a small boost in the bass region, and a gentle fall to the extreme treble. Click on Auto Target to have IRC Measure estimate a suitable target curve. You can adjust the target curve by clicking and dragging on the circular grab-points. Double-clicking on the curve will create another grab-point. Drag-selecting a region will zoom in on that region of the graph, and double-clicking will zoom back out again.

You may find you need to experiment with different target curves to determine what works best for your system in your room, as there is no universally "correct" in-room response. Once you have the target curve set, click on the Optimize button. This will generate the correction filters and display the predicted response.

Corrected in-room response

Click on Save Filter to save the correction filter as a file for import into Amarra Symphony. The default location is ~/Library/Application Support/Dirac/Filters, but you can save the file to another location of your choosing.

6. Load and listen!

In Amarra Symphony, click on the IRC button:

IRC Button

This opens the IRC window. Double-click on one of the slots to select and load a correction filter. You can load up to four correction filters into Amarra Symphony. This allows for easy auditioning of different target curves and enables you to keep different correction curves loaded for different purposes.

Loaded filters

Now start playing a file, sit back and listen! You can now experiment with different target curves to determine what works best with your system and room. Note that if you move your speakers, or add acoustic treatments to your room, you will need to redo the measurements, so keep your UMIK-1 handy!


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