This app note shows you how to set up the UMIK-1 and Room EQ Wizard (REW) on Windows, together with a device with HDMI input such as an A/V receiver or a miniDSP home theater processor. This enables you to select individual output channels for use in measuring and equalizing a home theater or multi-channel surround system. You will need a computer with an HDMI output port.

• 1. Get your calibration file
• 2. Download and install software
• 3. Get connected
• 4. Configure Room EQ Wizard
• 5. Configure ASIO4ALL
• 6. Select input and output channels
• 7. Test
• 8. Measure
• What's next?

1. Get your calibration file [Top]

Go to the UMIK-1 page and enter your microphone's serial number. It is in the form xxx-yyyy and labeled on the microphone. Ensure that you download both the regular calibration file and the 90-degree calibration file.

The calibration file ensures that your microphone is as accurate as possible. Each microphone has two unique calibration files, which is why the serial number must be entered. The regular calibration file is used when the microphone is pointing at or between the speakers, and the 90-degree file is used when the microphone is pointed at the ceiling.

2. Download and install software [Top]

You will need to download and install two items of software:

• Download and install Room EQ Wizard from www.roomeqwizard.com.

• Download and install ASIO4ALL from www.asio4all.org. When installing, the optional components don't need to be installed.

3. Get connected [Top]

Mount the UMIK-1 into a microphone stand. For home theater applications, it's easiest to point the microphone at the ceiling and use the 90-degree calibration file. Connect the UMIK-1 to your computer with a suitable USB cable.

Connect the HDMI output of your computer to a suitable HDMI input of your A/V receiver or miniDSP home theater processor. Check that your receiver is set for multichannel output e.g. 5.1 or 7.1, and not to a stereo downmix.

4. Configure Room EQ Wizard [Top]

Start REW. You will see a screen asking if you want to use the UMIK-1. Click Yes.

Answer Yes to the next question about the calibration file:

Use the dialog box that appears next to locate the 90-degree calibration file that you downloaded in Step 1 above. It will have a name like "7013462_90deg.txt". (This assumes that you have pointed the UMIK-1 towards the ceiling.)

The main functions will now be accessible from a row of buttons at the top of the window. This screenshot highlights the functions we will use in this app note:

Click on the Preferences buttons and make the following selections (in this order):

• Under Drivers, select ASIO.
• Under Sample Rate, select 48 kHz.
• Under ASIO Device, select ASIO4ALL v2.

Then click on the ASIO Control Panel button. This opens up the ASIO4ALL control panel.

5. Configure ASIO4ALL [Top]

In the ASIO4ALL control panel, set advanced mode. This is done by clicking on the wrench or spanner icon at the lower right. In advanced mode, there will be additional controls in the window and the wrench/spanner will have a red X over it.

In the list at the left, enable the HDMI audio device and the UMIK-1. You should deselect other audio devices to avoid clutter when selecting input and output channels in REW.

Audio devices don't always appear with obvious names, depending on the device and the version of Windows. For example, the UMIK-1 may appear just as "USB Audio Device." By hovering the mouse over the device you will get a popup window with more information that helps to identify the device, as shown in the screenshot above for the HDMI output.

6. Select input and output channels [Top]

Quit REW and start it again. This is to ensure that REW has the latest set of channels in the ASIO4ALL driver. Open Preferences again and in the Input drop-down selector, select the first channel:

In the Output drop-down selector, you should see eight channels - these are your eight HDMI audio channels. Set it to the first channel:

7. Test [Top]

Before proceeding, turn down the volume on your A/V receiver.

Click on the Generator button:

Set the signal generator to Pink Noise and select the "Full range" radiobutton. Set RMS Level dBFS to −20.0. Drop down the Output selector and select channel 1, then press the triangular green Play button. Gradually increase the volume on your A/V receiver - you should hear sound coming from the front left speaker.

Click on the SPL Meter button. Click on the red button to turn the meter on. Increase the volume on your A/V receiver until the SPL reads about 75 dB.

Press the Play button again to stop the signal generator. Change the channel selector to 2 and press Play again. You should hear sound from the right speaker. Continue through the remaining channels to check that they all work as expected.

8. Measure [Top]

You are now all set to run a measurement sweep. Click on the Measure button:

1. Check the start and end frequencies.
2. Check that the level is -20.0 dB.
3. Drop down the channel selector for Output and set it to channel 1.
4. Click Check Levels.
5. Click Start Measuring.

You will hear a sweep through the front left speaker, and REW will display its first frequency response graph. Repeat for all channels by clicking on the Measure button and changing the channel selector each time to 2, 3, and so on. We recommend that you change the name of each measurement as you go to keep track of which is which. After completing all channel measurements, you can view them together in the Overlays window.

Apply some smoothing to the graphs using the pop-down Controls overlay. You can turn the display of individual graphs on and off with the checkboxes underneath. You should have a result like this:

What's next? [Top]

Now that you have the ability to run acoustic measurements, you can proceed to optimize and equalize your system. Check out the acoustic measurements and home theater tuning app notes on our web site. Have fun! Don't forget to let us know how you go in our forum.