Room Measurements

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Audiosaurusrex

Room Measurements
« on: 30 Nov 2021, 03:14 pm »
I understood that my room needed to be treated with my Spatial M3 Sapphires but being new to understanding room acoustics and purchasing a number of absorbers and diffusors from GIK, I was curious to do a room measurement of my room 16x18x8 hard wood floors. I purchased the UMIK-1 and using REW did my first measurement. I'm hoping I used it correctly but I did set up the mic in my listening position. I think I read somewhere that there's a lot more than just the sweep but the difference between whats generated and what's recorded. Not really sure what I'm looking at so if anyone can assist me in understanding the graph I'd certainly appreciate that. Thanks in advance.



JWL.GIK

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    • GIK Acoustics
Re: Room Measurements
« Reply #1 on: 30 Nov 2021, 04:03 pm »
Nice work! You are now officially an audiogeek. :-)

It's true, I almost never look at simple response graphs. I think the time-based measurements give us much more an idea of how the room actually sounds. Spectrograms, waterfall graphs, ETC/Impulse responses, RT60 times, etc. Keep in mind sound is a time-based phenomenon so the time-based data is critical, much more so than a frozen snapshot in time from a graph.

The main thing we are after is consistent decay times across the frequency spectrum, in the bass range I'll look at a waterfall graph, or the spectrogram is great for a "view from 30000 feet". And the Impulse/ETC gives us a lot of info about early reflections and clarity. My very first article years ago on the GIK site was about ETC if you are interested in that.

Tons of good info in the REW help/manual also.

Audiosaurusrex

Re: Room Measurements
« Reply #2 on: 30 Nov 2021, 06:18 pm »
Getting the hang of this:
Waterfall and Decay, not quite sure how to read it but it's fun watching my dogs ears go up  :duh:





Big Red Machine

Re: Room Measurements
« Reply #3 on: 30 Nov 2021, 07:44 pm »
Nice. See how the waterfall mimics the graph above. You have some wooly base to tame. And your 150 to 500 is dipping down ever so slightly.

Trim you graph from 20 to 20,00 and play with the resolution to say 1/6 for less busy-ness. Most folks hate that smoothing level of 1/6 but you need to adjust the big hitters first before worrying about the minutia.

You have the mic vertical? It's at ear level? At your normal sitting position. If using a tripod, move the mic forward and backward and take measurements just to satisfy your curiosity about how the room influence the sound. Then try moving the speakers out from the sidewalls and front wall. It's fun.




Audiosaurusrex

Re: Room Measurements
« Reply #4 on: 30 Nov 2021, 09:09 pm »
Nice. See how the waterfall mimics the graph above. You have some wooly base to tame. And your 150 to 500 is dipping down ever so slightly.

Trim you graph from 20 to 20,00 and play with the resolution to say 1/6 for less busy-ness. Most folks hate that smoothing level of 1/6 but you need to adjust the big hitters first before worrying about the minutia.

You have the mic vertical? It's at ear level? At your normal sitting position. If using a tripod, move the mic forward and backward and take measurements just to satisfy your curiosity about how the room influence the sound. Then try moving the speakers out from the sidewalls and front wall. It's fun.
Big Red,
I appreciate your help on this. So this is my therapy while I recover from hip surgery. I have placed the mic in my listening position at ear level some what pointed to the speakers. My rug is not on the floor currently as per my doctors instructions, obviously not an audiophile  :lol: and side curtains were open during the day but I'll play more tomorrow. I tried smoothing out the graph Big Red I think I did it right. Not sure about how to trim the graph though.
Here's what I have now:





Big Red Machine

Re: Room Measurements
« Reply #5 on: 30 Nov 2021, 11:31 pm »
I believe the mic should point straight up, not forward. It won't make a mega difference but I believe that is the recommended orientation.  Curtains and rugs will not do much for you. Your bass hump is the gorilla in the room right now. But move the mic around and see how the bass changes in the graphs (frequency sweeps) and the light will go off for you.

I ended up sitting back farther than I normally do because I could not avoid a null where I usually like to sit (62% back from front wall). So I measured about every 8 inches from there backwards until I found a spot that leveled out the response. I have poor mathematical numbers 8 x 16 x 20 so lots of frequency boosts to deal with.

I spent time getting my speakers located first to get more even bass response and you can see those results (but keep the mic location consistent so you have apples to apples).

It will take a ton of trapping that is not feasible to flatten that bass hump unless you move your chair or your speakers.

Plug your room measurements into this and see if the frequencies line up with your measurement. Your room is the gorilla's mom!
http://www.bobgolds.com/Mode/RoomModes.htm

I'm not the expert. They'll be along soon.

Keep notes and save those files with good names that mean something next year.

Audiosaurusrex

Re: Room Measurements
« Reply #6 on: 2 Dec 2021, 07:02 pm »
Made some adjustments. GIK Acoustic Panels are now directly behind my M3 Sapphires aprox 1 ft. These measurements were taken from the coffee table in front of my listening position. I guess I might have to sit on the floor for optimal acoustics  :roll:





TJ-Sully

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Re: Room Measurements
« Reply #7 on: 13 Dec 2021, 02:50 am »
hey guys, great info here in the GIK site.  thanks for everything!

Looking for a little guidance on my REW measurements in my room.

I have recently taken some frequency response measurements, and other than the bass region (which is a big deal, I know), I am fairly happy with the shape of the curve.

But, when i hit the waterfall graph option, my setting seem to be all messed up.  The entire frequency range is pushed against the front....when I know only the bass region normally shows this. Can someone please offer some guidance on the waterfall graph settings? 

I took a photo of the response, but failed to take a pic of the waterfall graph - and unfortunately, the saved file no longer opens (says it's not in the proper format).

Anyhow....I would certainly appreciate any experienced REW users' help along this journey!

Thanks! TJ