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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 of the listening area. An easy way to achieve this would be to use the RTA and noise generator in REW. The process described here is often referred to as the "moving mic" measurement method.
Latest and greatest REW version as of today is here, it includes a LOT of new stuff and fixes:
https://www.avnirvana.com/threads/v5...s-build.11154/
- Open the RTA window in REW. Select the gear icon and configure it like this. It's important here that RTA mode is selected, not spectrum mode.
- Open the Generator window. Select pink periodic noise. Note the sequence length is the same as the FFT length in the RTA window. I always measure at 96kHz, so a 128k length makes a new measurement every 1.33 seconds. With 50% overlap, a new measurement will be completed every 0.66 seconds. If measuring at 48kHz, feel free to lower the FFT and generator sequence length to 64k for the same time duration of measurement. Decreasing to 32k or 16k is probably fine as well for fast measurements, but with some decrease in resolution at very low frequencies.
- Now, hold your mic in your hand like it's a magic wand. The mic can be oriented towards the speaker or towards the side, I usually stand to the side with arm extended to reduce influencing the measurement too much. Even though measurement microphones are omnidirectional, they're not perfectly omnidirectional, so you will very likely notice a difference in response slope >5kHz if you complete this process with the mic facing forward vs the mic facing sideways so keep this in mind. Issues in the top end should really be addressed by the crossover anyway, with room EQ applied <1kHz, usually <600Hz.
Take care not to tap on the mic, adjust your grip, jostle the cable, jingle your keys or sneeze while measuring. Measurement mics can be very sensitive to pickup noise in the body of the mic which will affect low frequency measurements.
Alternatively, if you have a boom stick, mount the mic at the end of the boom stick and wave it around the listening area from a distance. This will help prevent both noise pickup from holding the mic as well as reduce effects of your body in the measured results. - Press play on the generator, and record on the RTA. Use a reasonable SPL around 80-85dB for measuring to maintain high SNR. Wave the wand around your listening area where your head is, make circles about 18" diameter. Move at a slowish but steady pace. You will see the RTA settle to a consistent shape after 30 or so averages. You can stop recording now.
- Press the "save current" button on the RTA. In the "All SPL" tab of the main window, apply phychoacoustic smoothing.
- Repeat this measurement process a few times if you like, just to see how repeatable this method is.
- You have now created a room response, ready for EQ. "Flat" is not the target for this EQ. Recommend trying the REW default target of 1dB/oct slope below 200Hz, and 1.5dB/oct slope above 1000Hz. Alternatively, try a constant 0.7 - 1.5dB/oct slope for the entire frequency range.
Alternatively, you can take many individual measurement and average them in REW using "vector average" in the All SPL menu. You'll have the benefit of having a complete impulse response of each measurement for additional analysis of RT60 decay, waterfall, etc. which you won't get with RTA.
