Installing and Configuring REW on Windows
Continuing the effort to re-set up Room EQ Wizard (REW) on a Windows Home Theater PC, this page documents the installation and configuration of REW by describing the step-by-step process of setting parameters in the program's preferences. This process assumes the use of a UMIK-1 and FlexASIO. The first section on this page includes a brief overview of the measurement goals, which informs how some settings are configured.
Last Updated: 03/31/2025
Background
Having completed the steps from the previous page, hopefully, Windows will be configured consistently with REW requirements, and drivers and microphone calibration files will be loaded on the PC awaiting REW. The next step is installing REW and configuring REW for the measurements I want to run. The basic home theater measurements that provide a good understanding of the system's performance are:
-
Frequency response measurement
-
Impulse response measurement
-
Reverberation time measurements
The data from the above measurements can be analyzed to see if modifications to the room and/or speaker placement can improve the sound.
REW can do much more than taking some measurements. It can be used to set a desired Target Frequency Response Curve, compare actual frequency response measurements with the desired frequency response, and generate parametric filter values to be used by an equalizer to "correct" the room's frequency response.
As a novice at using REW, generating equalizer settings was not considered for this write-up. For this write-up, the focus is on creating the setup for doing the above three measurements.
The version of Room EQ Wizard used for this write-up and the version pictures were taken from is v5.31.
Figure 1. REW Download Options from REW Website
One more comment- well, more like a disclaimer- the author of these pages (me) is not an expert in REW (more likely considered a novice). This page and subsequent pages start by capturing the basic usage of REW from a novice's perspective. Perhaps later on, more advanced topics such as using REW to model a room's acoustics and using REW to generate PEQ filter parameters, which can be loaded into an AVR or miniDSP to compensate for frequency response issues, may be covered. So to start, these pages document some basics of REW, first the setup then taking straightforward measurements.
Installing Room EQ Wizard
Download and install Room EQ Wizard from www.roomeqwizard.com, Figure 1. Then, run the installer and accept the defaults. If I had planned on taking more extended measurements, e.g., >1M samples, I may have wanted to change the setting on the left of Figure 2, which increases the memory setting from the default of 1GB.
(Note: My computer is set to dark mode, so this is the reason that the screen captures appear as they do. I like dark mode when it is supported.)
Figure 2. REW Installation Dialog Menus. Initial Dialog Box (left), and the Memory Selection Dialog Box (right)
Figure 3. Final REW Installation Dialog Menu
Starting and Configuring REW
On the last REW installation panel, Figure 3, the user can start REW immediately, so why not? When running REW for the first time, it is best to plug the UMIK-1 into the PC before starting REW. REW will automatically detect the microphone and display a few set-up pop-ups to assist in setting up the UMIK-1. Figure 4 shows most of these, starting with the upper left dialog, which asks the user if he wants to use the UMIK-1. Then, REW asks for a calibration file. If the user answers YES, then REW pops-up a dialog box for the user to point REW to the desired calibration file.
Figure 4. REW Start-Up Pop-Up Dialog Boxes The Very First Time REW is Run. First Pop-Up is Upper Left, Second Pop-Up is Upper Right and Last Pop-Up is Bottom Center.
Once REW has started, and after the initial dialog boxes have been dealt with, the user is left with the main Window. The Windows menu bar is at the very top of the main window, and just below the menu bar is the toolbar where the most important actions are initiated. (see Figure 5). To configure REW, one selects the Preferences tool on the right of the toolbar (see Figure 5, yellow box on the right).
Figure 5. REW Main Toolbar Highlighting (in yellow) the Preferences Tool.
Selecting Preferences opens the configuration window, shown in Figure 6. The first tab is the Soundcard tab, which is the only tab that requires configuration to start measurements.
-
Select the ASIO Driver, highlighted in yellow
-
Double-check to ensure the Sample Rate (red oval) is set to 48Khz
-
Select the ASIO device (orange oval). In this case, FlexASIO.
-
Then, open the ASIO control panel (blue oval).
-
In the ASIO Control panel (blue outline), select the correct input and output devices. For my setup, the input device is the UMIK-1, and the output device is a Denon receiver. Then, close the control panel.
-
Next, select the Reload button (Light Blue Oval) to force REW to load the correct driver.
-
Check the Output setting; I set it to 1: OUT0, but this will be changed when generating a measurement. Make sure to select an input. I selected 1: IN 0 (This is shown in the indigo ovals).
-
Under the Levels section, one can use a subwoofer or main speakers to set levels for general measurements through an AVR. Still, I usually select "Use main speaker test signal . . . . " (The darker green oval at the bottom of Figure 6.) Since I intend to test speakers in combination with subwoofers, either choice should be fine. If I were only testing subwoofers, I would use the other selection.
-
It's unnecessary for basic testing, but I also set the Timing Reference Output to the center channel—3: OUT2 (purple oval). This setting is used for timing/distance measurements for speaker time alignment. Since the Denon AVR's Audessey feature does this measurement, it is unnecessary to use REW to do this, but it might be interesting to check Audessey.
Figure 6. REW Preferences Panel, Soundcard Tab, and ASIO Control Panel
The cryptic numbering scheme in the Soundcard Output drop-down menu corresponds to the following speakers:
-
OUT0: Front left
-
OUT1: Front right
-
OUT2: Center
-
OUT3: Subwoofer
-
OUT4: Surround left
-
OUT5: Surround right
-
OUT6: Rear surround left
-
OUT7: Rear surround right.
This same numbering scheme is used in other REW menus to determine which speaker to test.
The next tab in the Preference dialog box is CalFile. In this menu, there should be nothing to do except check that REW selects the desired calibration file for the desired driver. Since ASIO is being used, only the FlexASIO Mic cal files item must be confirmed, as highlighted in Figure 7's yellow box.
The remaining tabs (Comms, Analysis, Equalizer, and View) don't require any setting changes to run the basic measurements made for home theater testing, namely Frequency Response, RT60, and Impulse Response measurements. But I'll point out a few additional settings to be aware of.
Figure 11. REW CalFiles Tab in the Preferences Panel
In the Comms preferences tab, which has only a couple of settings, since taking measurements does not use MIDI, this was disabled. This likely does nothing noticeable but possibly saves a few cycles, preventing the PC from servicing this interface.
Figure 12. REW Comms Tab in the Preferences Panel
The default settings on the Analysis tab (not shown) are acceptable for the planned measurements, so I did not touch them.
The Equalizer tab (not shown here) is an interesting menu. This feature is not used for taking measurements but is utilized when one wants to use REW to determine how to set up filters to adjust the sound. REW can compare frequency response results to a target curve specified by the user. It can then determine the parametric EQ (PEQ) settings needed to adjust the source audio's frequency response to align with the target curve. This process could warrant a separate tutorial for further explanation.
The last Preferences tool Sub-Menu tab is the View tab (Figure 13). Again, the defaults for this menu are pretty reasonable for taking measurements. Still, if one has some particular preference for how the graphs are presented, there are many tweaks available in this menu. One configuration to mention is the Maximum Measurements. Generally, for doing basic measurements, the default value is fine; however, when working on more advanced tasks like taking measurements to generate PEQ filters, it may be necessary to take many measurements, and in this case, the Maximum Measurements value needs to be increased.
Figure 13. REW View Tab in the Preferences Panel
After configuring REW as shown above, the next steps are to test the microphone and ensure the connections and configuration are correct. This is followed by taking some measurements, which are described on the initial measurements page.