What Is Room EQ Wizard (REW) and What Can It Do for Room Acoustics?

Room EQ Wizard (REW) is free room acoustics measurement and analysis software for Windows, macOS, and Linux. It measures rooms, speakers, subwoofers, and audio devices, then helps you interpret the results and configure EQ to address room problems. It suits home listeners, studio users, and home theater owners who want to find better speaker and listening positions and understand how their room affects sound. You need a computer, a compatible measurement microphone, and an audio interface or the computer's sound hardware to take measurements.

What REW measures and analyzes

REW is built around measurement and analysis of the audio reproduction chain. According to the software's own description, it helps you:

• Measure rooms, speakers, subwoofers, and audio devices
• Find the best locations for speakers, subwoofers, and the listening position
• Analyze the performance of the whole audio reproduction chain
• Configure EQ to help tackle room problems

The site's keyword list points to the analysis areas the software covers: room modes and resonances, parametric equalizers, spectrograms, and the BFD (Behringer Feedback Destroyer) hardware commonly used for subwoofer EQ. In practice, this means you can look at frequency response, identify resonances and room modes, view how sound decays over time with a spectrogram or waterfall-style display, and calculate parametric EQ filters to counter peaks.

A concrete example

Suppose you measure your listening position and see a strong peak around a low frequency. REW lets you examine the response, identify the resonance, and generate parametric EQ settings to reduce that peak. You can then apply those settings to a compatible equalizer and re-measure to check the result. The same workflow applies to comparing subwoofer placements: measure, move, measure again, and keep the position with the smoother response.

Downloading and installing REW

The current version listed on the site is V5.31.3, released 25 July 2024. Previous builds are also available, and beta versions are hosted at AV Nirvana, which also runs the REW support forum.

A sample measurement file (Sampledata.mdat) is also provided, which is useful for exploring the software before you take your own measurements.

macOS permission note: the site advises that you may need to use the Mac's Privacy settings to grant REW access to the microphone and to the folders where measurements are saved, particularly if those folders are on the desktop. If measurements won't save or the mic isn't detected, check these permissions first.

Help files, tutorials, and support

REW includes comprehensive help information inside the application. You can also:

• View the help files online
• Download the HTML files for offline viewing
• Download a PDF copy (V5.20, September 2021, courtesy of Steve Bolser)

The site notes that the online and in-application help files are the most up to date, while PDF files are snapshots from their generation date. Online help for the current beta is available in the Beta help files. For tips and assistance, the AV NIRVANA REW forum is the designated support community. Translations of the V5.20 help file exist in French (by Patrick Del Basso, January 2022) and Chinese (by Johnson Chow of Initial Audio Concept, October 2021).

Free version vs. the Pro upgrade

REW is described as free software, and donations are welcomed to keep development going. A Pro upgrade adds capabilities beyond the free version. Per the site, the Pro upgrade offers:

• Simultaneous measurement of multiple inputs with RMS averaging
• Adjustable weighting for each input
• Level alignment
• Up to 16 input traces on the RTA, in addition to the RMS average
• Calculation of Speech Transmission Index from the impulse response by the indirect method per IEC 60268-16:2020

If you only need single-channel room and speaker measurements with EQ calculation, the free version covers the core workflow described above. The Pro upgrade matters if you need multi-input simultaneous measurement, per-input weighting, or Speech Transmission Index calculation. The site does not list a price for the Pro upgrade, so check the Upgrades page for current terms.

Getting started

1. Download the installer for your OS from the Downloads page and install it. On Linux, confirm a Java 8 runtime is present.
2. Connect a measurement microphone and confirm the OS and REW can access it (on macOS, check Privacy settings).
3. Open the sample data file to familiarize yourself with the graphs before measuring your own room.
4. Take a first measurement at the listening position, then review frequency response, resonances, and the spectrogram.
5. Use the EQ tools to generate parametric filters for the problems you find, apply them to your equalizer, and re-measure to verify.

The main practical hurdles are microphone and file permissions, especially on macOS, and interpreting the first set of graphs; the in-app help files and the AV NIRVANA forum are the intended resources for both.