I picked up a UMIK-1 and have been busy taking measurements and playing with speaker placement and such. I have a comb filtering or cancelation issue(i think) in the 60-70hz range that I really want to add treatment to the room instead of boosting the frequencies. I am running polk r700’s which measure flat at the speaker so I am sure there is a room issue here. I could bandaid the issue with crossing my dual Speedwoofer 10s much higher but they really shouldn’t need to play over 40-50hz at the most with the 700’s.
Any suggestions would be welcome. Below is my base in room response with VAR smoothing applied along with a screenshot of the front of my 13x24 ft room. There has been no filtering or anything applied as of yet, this is just the measurements L/R channel. It is a rental so nothing can go on the walls unfortunately.
Those are room modes caused by standing waves - the wavelength being close to room dimensions and a low multiple of them.
If you measure around your room, you’ll see drastic differences in boosted/cancelled frequencies, so trying to compensate for one location is futile.
Thusly only rearranging room positioning to not aggravate standing waves too much and adding room treatment are your only choice.
Definitely avoid placing speakers equidistant to room boundaries and stuffing your subwoofers in corners.
What are your room dimensions, anyway?
How are you taking your measurements, exactly?
Maybe try the moving mic technique for one speaker at a time, slowly sway the mic forward/back up/down left/right at least an arm’s length around you with pink noise signal for like half a minute while applying psychoacoustic averaging to get a measurement closer to how your aural impression of the room acoustics would be.
Thank you for the suggestions. I am going to be busy this weekend moving stuff around and taking more measurements. My room is 13 wide by 24 long with a kitchen in the back. My listening position is 12 feet from the back wall (for now) and my speaker baffles are 3.8 ft the back wall and 3 ft. from the side walls. I thought that would be enough so that they weren’t interfering from the side and front wall. The subs from multiple subwoofer crawls are in their optimal position to my ears. In. this position, They are the tightest and have the “sound” I am wanting from the subs. Unfortunately, I haven’t figured out how to measure them yet because my ambient noise levels are higher than where I would need to place the gains on my subs, so having difficulty measuring them. I run the subs at about 15% gain and that is where I feel they are reinforcing the speakers and not adding more than the speakers. I understand I probably am just not knowledgeable enough about how they should sound.
I really appreciate you defining the Mode for me. This will help me research into how to add treatment and adjust speaker placement based on the measurements. I am extremely impressed with the r700’s though even before applying any type of measurement based eq. I changed them from the Linton’s I had before and they are better in pretty much every way.
Again, thank you so much for taking the time to help me. I am excited to see what I can do with your observations.
So, how’s your method, if you don’t mind me asking a second time…
You’d measure without and then with them to see their influence - and that is not just caused by level but also phase, so there might be cancellations with them in comparison to without, necessitating a phase/placement adjustment.
Make sure to measure background without a stimulus also to get an idea for how loud you got to go while measuring - you definitely need to get more than 20dB of signal to background noise for any frequency region of interest to start being able to extract meaningful information.
AceRimmer
(Smoke me a kipper, I'll be back for breakfast!)
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My setup is a Roon Rock NUC into pontus II dac to a Freya+. I don’t have the ability to hook up an AVR through HDMI which almost all of the guides assume so I am taking measurements with the UMIK-1 usb into macbook air out via airplay to an extra node 2i I had laying around.
I have tried both sweeps and Pink noise (moving microphone). I like the Moving Microphone method as I can take the measurements and see the averages for the area of the room I am measuring. The sweeps can average out as well but I feel the moving microphone is probably more organic. The issue that I am running into is that with the pink noise, there isn’t an impulse that is recorded. I am not able to export the impulse to a wave file from the eq measurement that I am able to then move into Convolution on Roon.
I only seem to be able to see the RTA measurements when I do the moving mic with pink. So no waterfall or impulse. It’s probably just something I am missing in the settings though as I only have about 4-5 hours of playing with REW.
The videos on youtube and the very in-depth guide that everyone links to here seem to be able to get the impulse and waterfall from their measurements with the moving mic so I wonder what I am missing. I am setting everything exactly like they have it in the guides.
Thank you so much for taking the time to help a stranger. I am absolutely geeking out on all of this and love it, but I feel like I am just on the cusp of being able to understand the whole process but am missing one piece.
You can export any measurement signal from REW as a wav-file, import it into Roon to play while measuring…
Averaging a number of measurements while the microphone remains put is done to maximize signal to noise ratio, especially in the lower registers.
The moving mic method, on the other hand, averages over position to minimize the influence of standing waves at the measurement position in the region below, and to capture more like the sound power response above the Schroeder frequency.
The sound power response is what mainly determines our perception of sound balance in typical listening rooms.
You are never using the measurement result for your convolution.
The measurement, however derived, is used to generate filters, either in an automated or manual process, or a combination of both, which will flatten the response when applied.
The filter response is more or less the inverse of the actual response in relation to a target response, and that’s what you export to use for convolution.
One last comment regarding your remark about impulse and waterfall curves:
Only a measurement with fixed microphone position is useful to extract meaningful time and frequency domain aspects via so called Fast Fourier Transform maths.
That’s why you’re only able to see, i e. energy-time, reverberation-time, waterfall, step or impulse responses in that mode - but that can be done not only with sweeps, but also with so called maximum length noise signals (which are not random but known to the algorithm, sample for sample).
The filter response, Oh! So I export the filter response as a wav which is the corrections and load that into Convolution! OOOOHHHHH! That makes so much more sense
You gave me a bunch of terms such at max length noise signals and sound power response that I am going to have to learn about and have not heard before.
Thank you for the definitions of the differences in the measurements. That made a ton of sense as well. I think with your help I am on the right path.
Again, thank you for taking the time. I very much appreciate it and will put it to good use!
Bingo! I got this! Lol, Now I am understanding @Marin_Weigel
The difference is just amazing. Everything is so much more even, tighter, and the highs are just so smooth. The bass no longer feels like I am in a dance club. Don’t get me wrong the R700’s have plenty of weight but this really helped me even out the low end transition. And not a single bit of gain added (Good for me)
