Windows Setup Before Installing REW

I recently reconfigured Room EQ Wizard (REW) on the Theater PC and decided to document my setup. This page outlines the steps for preparing a Windows PC for a Room EQ Wizard (REW) installation. Before detailing the Windows software setup, the first step is to specify the hardware and connections needed to measure audio performance accurately. Once established, the steps to configure Windows for capturing audio from a microphone while outputting test tones are explained.

REWSetup

Last Updated: 12/12/2024

Introduction

After all the research and work to construct what hopefully is a good-sounding home theater, the question arises: How accurate is the theater's sound reproduction? It sounds pleasing (to my ears), but human ears don't provide quantitative information on how well the design turned out and where deficiencies might be.

The best way to obtain this information is to measure specific aspects of the audio, such as frequency response and sound decay times. Fortunately, today, the equipment to perform accurate acoustical measurements can be acquired very inexpensively. If one already has a computer or laptop, then what is needed is a measurement microphone and a frequency measurement software package, which can be purchased for less than a few hundred dollars (US). The most expensive part of acquiring the measurement data is the time to set up and learn how to run the tests correctly and to take the many data points required to determine a room's sound characteristics.

Once the data has been gathered, it can be analyzed to determine the accuracy of the sound reproduction. If the room does not reproduce sounds accurately enough, the data can be further analyzed to determine what changes should be made to improve the sound reproduction.

The first step in this process is to set up the measurement system. I used Room Eq Wizard (aka REW) for the measurement software. This powerful (and free) audio measurement program generates test signals and uses a microphone to capture the audio generated by the room's sound system.

The installation and configuration of REW requires several steps, as many options are available within REW. Recently, I re-set up Room EQ Wizard (REW) on my theater PC, so I wanted to document the setup process in detail so that if I ever needed to do it again, I'd have the setup information. I reviewed several written and video setup guides before redoing my setup, and I found in most of the guides that some details were missing, or in the case of the video guides, they were difficult to use as I was constantly pausing and rewinding to make sure I had set all the parameters necessary.

There are several ways to set up REW. This page describes installing and configuring REW on a Windows 11 PC. This write-up limits its scope to just the steps that I took. The starting assumptions are:

Using a Win11 PC,
Using a miniDSP UMIK-1, directly connected to the PC.
The PC is directly connected to a Denon AVR via HDMI.
The initial goal is to measure a home theater surround sound system (e.g., multi-channel setup)

Connect UMIK-1 and AVR

The figure shows the essential equipment connection. UMIK-1 connects to a PC/Computer using a USB cable. (In my case, a USB-C to USB-B cable), and the PC connects to the AVR via an HDMI cable (assuming a multi-channel setup).

This figure illustrates how to connect a USB Mike, AVR and PC to setup an acoustical measurement system.

Figure 1. Connection between UMIK-1, PC and AVR

Confirm the PC's Sound Configuration

Since the goal is to use REW to calibrate a surround sound system, the first step is to ensure that Windows 11 is set up correctly to measure the home theater using a UMIK-1. Most of this setup is accomplished by configuring the Sound control panel.

Open the Windows Control Panel. There are a couple of ways to do this:
1. In the search window, type "control panel" and click on the result.
2. Or type Win+R to open a command prompt, then type "control.exe."
Select Hardware and Sound from the list in the Control Panel.
Select Manage audio devices (which opens the Sound control panel).
The receiver is connected to the PC via HDMI.

Alternatively, to get directly to the Sound control panel:

Type Win+R to go to the command prompt
Then type "mmsys.cpl" to open the Sound control panel.

As shown, a few settings must be checked and set within the Sound control panel.

Referring to Figure 2, select the Playback Device tab (1) and then select the appropriate HDMI output device (usually an AVR, in my case, the "Denon-AVR-3600H") as the playback device (2).
Select the Configure button, which brings up the Speaker Setup, and confirm that the PC's speaker setup is set to the proper multi-channel audio (4). In my case, I picked 7.1. I have not tried the ATMOS setting. Click through the various boxes to set and check the speaker configuration (not shown)
Next, select Properties (5), then the Advanced Tab (6), and make sure (for UMIK-1) that the sample rate is set to 48000 and the checkboxes are checked (7). Then select the OK button
Finally, for the Playback device, click on the Apply button (8).

Next, the Recording device settings need to be checked.

Referring to Figure 3, select the Recording Device tab (1). Then, select the appropriate input device (2), which, in this case, is the UMIK-1.
Then, select the Properties button (3) to confirm the proper UMIK-1 settings.
Select the Advanced tab (4). Next, verify that the sample rate (5) is correct and that the exclusive mode and priority checkboxes (6) are set. (In my case, I did not have to change anything.)
Finally, click the Apply button followed by the OK button (8).

Windows Sound Control Panel Playback Tab including the Configuration/Properties Menus

Figure 2. Sound Control Panel Playback Device Setup

Windows Sound Control Panel Recording Tab including the Properties Settings

Figure 3. Sound Control Panel Recording Device Setup

Install ASIO wrapper for REW.

When setting up REW in Windows, one of the first settings is to choose which driver type to use. REW defaults to using the Java driver included in the release. Several online tutorials use this driver, but other tutorials/setup guides (for Windows) use an ASIO (Audio Stream IO) driver. I have generally seen recommendations to use an ASIO driver for this use case because ASIO provides better performance and lower latency, even though it can be a little more complex to set up and use. I chose to use an ASIO driver for my installation.

The Java driver is installed natively with REW, but when using ASIO, it must be installed separately and should be installed before using REW. The choice of which driver to use does impact the configuration within REW. For UMIK-1, it is recommended to install either:

ASIO4ALL (main site) and driver download, or
FlexASIO (GitHub site) and drivers download.

The REW website describes installation steps using ASIO4ALL, while the MiniDSP website tutorial references FlexASIO, which seems a little newer and a little easier to use. Therefore, I decided to use the latter and describe the simple installation process in the following steps.

Download the driver (using the links provided above). For FlexASIO, the driver file is called something like FlexASIO-1.10b.exe.
Run the installer; see Figure 3. Accept the default installation location and click the install button.

After this, one more step was required before installing and running Room EQ Wizard's configuration.

FlexASIO Application Instalation Dialog Box

Figure 3. FlexASIO Install Dialog Box

Copy microphone calibration files

The UMIK-1 comes with calibration files that can be used with REW to improve measurement accuracy. If the UMIK-1 is purchased directly from miniDSP or a typical retailer, miniDSP provides two calibration files, which can be downloaded from their website (at this link). Figure 5 shows a picture of the form to input a microphone's serial number and retrieve the proper calibration files. There are two calibration files provided: one to use when pointing the microphone directly at the speaker and a second for pointing the microphone straight up (pointing at the ceiling), which is designated by the "_90deg" filename suffix.

I placed them in a folder on my local machine so REW can access them later when configuring REW. However, I did not use these drivers.

Screen Capture of MiniDSP's UMIK-1 Calibration file download.

Figure 6. miniDSP UMIK-1 Calibration File Download

Figure 7. miniDSP Calibration Files Downloaded for a UMIK-1

Instead, I ordered my UMIK-1 from Cross Spectrum Labs (CSL). CSL provides a flash drive with a more extensive set of calibration files specific to the purchased UMIK-1. Figure 8 shows the file list for the calibration files provided.

I am uncertain whether the extra precision of CSL's files is beneficial, but since the additional cost was minimal, I purchased from CSL. For home theater audio measurement, only one calibration file is required. The general recommendation from several sources is to take the measurements for a surround sound system with the microphone pointed straight up. Therefore, a "90-degree" file from either miniDSP (Figure 6) or CSL(Figure 7). For now, they should be copied to a known location on the PC and loaded into REW (shown on the next page).

Directory Filelist of Crossspectrum Labs UMIK-1 calibration filenames

Figure 7. Calibration Files Supplied by Cross Spectrum Labs

Next: Setup REW