Hi Marti,
Did you ever write up your room correctiion process using REW as I also have the Wiim Amp Ultra (and a minidsp umik-1) and would like to follow your procedure. If you have not I would really appreciate just a few bullet points of the overall process. Thanks in advance.
Hey I'm really sorry because I both took a nasty fall on my shoulder and I'm feverish at the date time. All of my remaining attention went to my kids for the last two weeks. But I do feel like everyone should at least get the chance to experiment with Room EQ and build on my findings.
The biggest "problem" I found with Wiim's Room EQ is that it just does an Auto EQ from the measured response to a target. The correction is being done by 10 PEQ filters, no time alignment or attempts at reducing standing waves. BUT as soon as you made an auto-correction profile, you can edit all of the 10 bands, allowing you to virtually build your own Room Correction EQ.
So step 1 would be to make a couple of auto correction's and save them. At this point, decide if you want to make corrections for each channel separately or for both channels at the same time. Because my focus was finding room modes, I choose both channels at the same time, but I want to experiment with individual channels in the future.
Step 2, connect a mic to a laptop and connect the laptop to the Wiim streamer. Install REW on the laptop, import the measurement file for your microphone and set the volume to your preferred reference level. If you only use music, output a -12dB signal and increase the volume to 85dB, if you also watch movies, output a -20dB signal and increase the volume to 85dB.
Step 3 is to do measurements in REW. Position the mic in several different locations of the room for each measurement. Average the measurements.
Step 4, fill in your room dimensions in REW.
Step 5, open the EQ window and in the right sidebar, scroll all the way down to room modes. Pay attention to the ones with a long time or a loudness over 85dB. Display the theoretical room modes based on your dimensions and you should be able to find matches. First order room modes and the ones below 150Hz are the most important to correct.
Step 6 create modal EQ filters using the data in the detected room modes. Using the waterfall graph, lower the peak so it loses energy just as fast as other frequencies and correct the frequency if you feel that it's necessary. Once ready, the modal filters can be changed to peak filters and anything with a Q over 24 can be set to 24.
Step 7, after you have spend your 10 EQ bands on the worst modal frequencies, create a measurement of the predicted frequency response. In the main window, set the smoothing to psychoacoustic.
Step 8, go back to EQ but now create an in-room target. (I made straight downward slope that matches the predicted measurement the best) Make sure the low frequency roll-off matches your measurement, detect reference level based on measurement and do an auto EQ.
Step 9, if you're satisfied with the results, overwrite a Room EQ filter in the Wiim app with the filter settings from step 6. Make a PEQ preset in WiiM with the filter settings from step 8.
Bonus step: make a new target. For quite listening, I made a loudness target. First I generated a flat target with a bass shelf and a treble shelf (using the settings that Yamaha uses on their Auto EQ), and then I applied that to the same slope. You only have to make a new PEQ preset for a new target.
Using this method, the Room EQ filters are always enabled and actually adress room modes and you can change the target frequency response with EQ presets. Having used other Room Correction systems before, you really get the best spacial results when your speakers are time-aligned and phase corrected. But at least cutting out those boomy, bloaty standing waves makes everything sound clear and fast.
