Guenter Villnow
Guenter Villnow

This app note shows you how to set up the miniDSP UMIK-1 or UMIK-2 and Room EQ Wizard (REW) on a Windows PC with an HDMI connection to an A/V receiver. This enables you to measure each channel of a home theater or multi-channel surround system.

While this app note is centered around HDMI, the same technique will work with USB multichannel devices such as the Harmony DSP and U-DIO8. Just use USB as the connection instead of HDMI.

1. Get your calibration files [Top]

Go to the UMIK-1 or UMIK-2 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:

Note: earlier versions of this app note used ASIO4All instead of FlexASIO. You can use that instead if desired. FlexASIO is a little easier to use.

3. Get connected [Top]

Figure 1 illustrates a typical measurement setup. The PC is connected to an HDMI input of an AVR, although other devices with HDMI input such as a Blu-ray player or soundbar can also be used.

HDMI measurement with UMIK

Figure 1. Typical measurement setup

Mount the UMIK into a microphone stand. For home theater and multichannel applications, point the microphone at the ceiling and use the 90-degree calibration file. Connect the UMIK to your PC.

If your PC has an HDMI port, use an HDMI cable to connect it to your AVR or processor:

HDMI connection from PC for REW measurement

If your PC doesn't have an HDMI port, you will need to use a hub or adapter with an HDMI output port. For example, USB-C to HDMI adapters like this one are easy to obtain:

HDMI connection from PC with USB-C hub for REW measurement

Check that your receiver is set for multichannel output e.g. 5.1 or 7.1, and not to a stereo downmix.

4. Set sample rates [Top]

Set the input and output devices to the sample rate that you want to use.

  • If you are using a UMIK-1, set the output device to 48 kHz. (The UMIK-1 can only be set to 48 kHz.)

  • If you are using a UMIK-2, set both the UMIK-2 and the output device to the sample rate that you want to use, between 44.1 and 192 kHz.

Open Control Panel, then Hardware and Sound, then Manage Audio Devices. On the Playback tab, click on the HDMI device and then Properties. Drop down the selector to set the sample rate. (Note that the AVR may not show up by its expected name. For example, it may show up as the name of your TV even though your PC is connected to your AVR. This is due to EDID.)

HDMI device sample rate setting in Windows Control Panel

If you want to change the name of the output device, open Windows Preferences, go to Sound and choose the HDMI device. Click on Device Properties and change the name there, for example:

Change HDMI device name for miniDSP and REW

If you are using a UMIK-2, go to the Recording tab and click on the UMIK-2 and then Properties. Drop down the selector to set the sample rate. (The UMIK-1 can only operate at 48 kHz.)

UMIK-2 sample rate setting in Audio MIDI Setup

5. Configure Room EQ Wizard [Top]

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

UMIK detected

Answer Yes to the next question about the calibration file:

cal file?

Use the dialog box that appears next to locate the 90-degree calibration file. (This assumes that you have pointed the microphone towards the ceiling.)

Select UMIK-2 cal file

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:

REW buttons

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

  • Under Drivers, select ASIO.

  • Set the sample rate to the rate you previously set in Control Panel. The example shows 48 kHz.

  • Under ASIO Device, select FlexASIO.

REW Preferences for ASIO and UMIK-2

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

FlexASIO Control Panel

Select the input device (UMIK-1 in our example) and the multichannel output device ("My AVReceiver" in our example). Click the button "Close panel and update config file." In the REW Preferences window, click on Reload so that REW detects the new I/O configuration, then drop down the output channel selector:

FlexASIO UMIK output channel selection

FlexASIO starts channel numbering at zero. These channels map to HDMI channels as follows:

OUT0: Front left
OUT1: Front right
OUT2: Center
OUT3: Subwoofer
OUT4: Surround left
OUT5: Surround right
OUT6: Rear surround left
OUT7: Rear surround right

To begin with, set the selector to OUT0 (front left).

6. Test [Top]

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

Click on the Generator button and set the parameters as shown below. -20 dB is a good starting point for the level.

REW Signal Generator

Position your microphone at the listening position and turn the volume of your system down. Click on the Play button (green triangle) and turn the volume up. You should hear sound from the left front speaker.

Change the channel selector to OUT1; you should now hear sound from the right front speaker. Continue through the remaining channels to check that they all work as expected.

Now open the REW SPL Meter. Click on the red button in the lower right corner to turn it on and adjust your system volume until the meter reads about 75 dB. Alternatively, change the output level in the REW signal generator.


Close the SPL Meter and Generator windows when done.

7. Measure [Top]

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

REW measurement window

  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 OUT0 (front left).
  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 measure all channels.

HDMI channel selection for REW measurement

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. For example, here are the subwoofer and left speaker in our test system:

Example measurements mode over HDMI with UMIK

What's next? [Top]

Now that you know how 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 website. Have fun! Don't forget to let us know how you go in our forum.


Related Products - Acoustic measurement