How to: Measure with REW for Room EQ

REW is a powerful tool, as is EQ, but getting it right can be challenging. The first step to achieving a good EQ profile for your space is to take in-room measurements. This document will detail an easy method to achieve quick and reliable results.

For room EQ, a single measurement at your listening location will not produce a good depiction of the overall room response. An average of many measurements around the listening area should be completed to create a room response for equalization...

The DIY Audio community is large and sometimes it's helpful to have a place that lists other communities to aid finding these other groups. Below is a list of other communities that you can check out.

DIY Audio Fourms

• https://www.diyaudio.com
• http://www.dcaudiodiy.com
• https://techtalk.parts-express.com
• https://www.audiosciencereview.com/forum/index.php
• http://diyaudioprojects.com/Forum
• Loudspeaker DIY Group Discord Server (Reach out to Reet for an invite)
• Erin's Audio

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Minimum phase for a speaker can be described of the phase of the frequency response of the speaker at it’s acoustic centre, or the phase without any excess phase or “time of flight” included. It can be calculated from the speaker’s frequency response using Hilbert-bode transform, or HBT. When comparing multiple minimum phase responses, we can say that the responses occur at the same point in space, ie. there is no physical distance between them. When measuring speakers and processing the...

Loudspeaker T/S often includes only a single Le value for inductance, however driver motors are usually much more complex than a single coil of wire, so Le on its own is not a very good description of the driver characteristics. An extended impedance model, or “semi-inductance” model can provide additional characterization of the impedance curve for greater accuracy.

Many Scan-Speak drivers include this data in the “advanced parameters” section of their datasheets, however the...

With a simple jig, loudspeaker impedance and T/S parameters can be easily measured with LIMP. The same jig may also be used to measure component value for resistors, capacitors, and inductors, as well as measure transfer functions of passive and active filters.

The setup is quite simple, the following diagram is taken from the LIMP manual:
https://artalabs.hr/download/LIMP-user-manual.pdf

Measurement Jig

This instruction is following what is in...

With VituixCAD, we have the ability to provide a mirror EQ function, that can then be passed to APO EQ for active processing. This allows for a speaker's frequency response to be fully compensated for without requiring many bands of parametric EQ.

VituixCAD Process

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Connect each driver and EQ blocks in the crossover section as shown. Ensure that the active peak/notch filters are “shorted” so that only the G(f) block is directly connected to the driver. Three PEQ blocks are show,...

With meticulous passive filter design, it may be beneficial to hear the result before spending money on crossover parts and putting in the time to assemble the crossover. Fortunately, with VituixCAD and EQ APO and filter can be simulated digitally. This process can simulate multiple drivers simultaneously, one driver for each output on a soundcard, for example a 7.1 soundcard could simulate a stereo 3 way system utilizing 6 channels.

Note that an emulated passive filter will reproduce...

Here's a schematic for a simple dual channel measurement jig, which can be used with ARTA, REW, or SoundEasy. This jig is made with USB audio interfaces in mind, so the use of 1/4" TRS connectors is recommended for this purpose. Main reason is that the 48V phantom power on audio interfaces is only present on the XLR pins, so use of TRS will ensure that 48V will only ever be present when a mic is connected, not when using this jig even if you leave phantom power turned on.

R1 should...

What does single channel or dual channel measurement really mean, and what are the implications of choosing one over the other? This document aims to help answer this.
Strictly speaking, a microphone is a single channel of audio input, in that it is a mono signal. USB microphones which include integrated ADC and USB codec can be considered a single channel device.

Dual channel would be a measurement which includes a second channel of signal input in addition to the microphone....

Update: Since VituixCAD 2.0.98.6, exporting IR using windowing as described here is no longer required. the impulse response can be exported directly, make sure to uncheck "normalize" on export. VituixCAD will automatically set "skip samples" to 1m (2.907ms) prior to the start time of the exported impulse response to maintain correct timing on import.

REW can export the measured impulse response directly as MLSSA formatted text file, which can be used within the...