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Turned My Living Room Into My Control Room
Old 11th September 2020
  #1
Turned My Living Room Into My Control Room

Hey Everyone. I've been around here for a while, learned lots. Spent a lot of time here when I was at my old condo rental so I could learn how to treat my living room for acoustics. I was able to get the response to +/- 5db with all frequencies over 40 hz to decay 30db in under 500ms. Was a pretty good learning project.

I just bought a house and based most of the decision on a living room with a lot of volume and vaulted ceilings. I found a great house that removed the 3rd bedroom to make the living room bigger. Took out a mortgage.

The whole place is tiled so there's lots of decay, but for now I wanted to just make an RFZ. Luckily the spot in the living room with the best response in terms of limited low bass issues was right against the wall, so I didn't have to put the desk too far off the front wall.

I chose OC 703 4in because it was readily available. I'm sure there may have been better products but this was good enough for me. I went 3 panels high horizontally) on the left, right, and front wall. I know there usually isn't a big benefit of treating the front wall but I actually wanted to hide some wires so I put some panels there. I did two panels above on the ceiling. I didn't want to build wooden frames because I didn't want to increase the weight and wanted as much absorption surface area so I went another method.

I saw some people here affixing corner bead to their panels to sharpen the edges for nice fabric wrapping. The ones I saw were using metal corner bead, but I waned to try vinyl. It seems like it wold be too flimsy but if you hot glue the corners and spray glue the rest it makes a suitable frame to hang via picture wire, which is exactly what I did. Bought some burlap and it wrapped nicely. Spend the extra money on fire ******ant and sprayed all the panels. I also put a layer of white felt between the burlap and the fiberglass (on front side only) so you didn't see the ugly yellow underneath the burlap. I glued hard foam blocks to the corners to make it stand off the wall 4in, and was able to epoxy D rings to the back of the panel for hanging. Used one picture wire and standard drywall anchors and it worked like a charm. Made a copper pipe stand for the 4 panels in front of the sliding glass door.

The result was actually pretty good in terms of frequency response, ETC, and decay times over 50hz, but there was a 15 db null at 106hz. I tried moving the speakers and mic but the null persisted, and seemed to equate to the distance to the side wall so I assume it was a modal issue. I am impatient and didn't want to have to start bass trapping or pressure trapping to fix the problem so I decided to try and fix it with a floor sub.

I went to Guitar Center and got a decent deal on a sub. Problem is the sub and my active monitors only crossed over at 80hz and my problem was at 106, so I put it into full bandwidth mode and shot the room just to see if the 106 null improved. It did. Reduced it to about 4db or so. That meant I needed a crossover. Back to Guitar Center I went.

Got a cheap DBX crossover and messed with the crossover point until I got it to the best response I could. Unfortunately I had to set the crossover to like 170hz to get the best response, which means I can't really pan anything under 170hz, but to be honest I usually mono all those frequencies so it was a reasonable trade-off. I was able to get the room to +/- 5db except for a couple of frequencies that poke above and below.

I attached some pics in case you're interested. Let me know if anyone has any questions. I like to post results because it may help someone here. I know that all of your posts helped me, so I wanted to spend the time to discuss this project.
Attached Thumbnails
Turned My Living Room Into My Control Room-l-r-final.jpg   Turned My Living Room Into My Control Room-final-both.jpg  
Old 11th September 2020
  #2
The 106 hz null is probably the floor bounce and SBIR.

The Null at 38hz is SBIR.
Old 11th September 2020
  #3
Zoomed out this much it doesn't look bad. But what does the spectrogram say?
Old 11th September 2020
  #4
Quote:
Originally Posted by thethrillfactor View Post
The 106 hz null is probably the floor bounce and SBIR.

The Null at 38hz is SBIR.
I originally thought that might be it too but I assumed the vaulted ceiling would make that unlikely for 106 hz. Do you think a vault would eliminate the possibility of it being floor bounce? I moved the speakers off the wall at least 5ft and the null was at the same frequency, wouldn't that indicate an issue with the left and right walls? 106hz translates to like 126in, which is almost exactly the distance from the speaker to the side wall..
Old 11th September 2020
  #5
Quote:
Originally Posted by johannburkard View Post
Zoomed out this much it doesn't look bad. But what does the spectrogram say?
Yeah but I made sure to offset the line so the average spl fell in the middle of a 10db row so you can see which frequencies go past +/- 5 db.

The spectrogram is about decay time right? That's gonna be my next project and will require lots of trapping in other areas of the room. For now, the frequency curve is fairly flat and the etc is free of first reflections that exceed -15db in the first 40ms.
Old 11th September 2020
  #6
Quote:
Originally Posted by Obe1 View Post
I originally thought that might be it too but I assumed the vaulted ceiling would make that unlikely for 106 hz. Do you think a vault would eliminate the possibility of it being floor bounce? I moved the speakers off the wall at least 5ft and the null was at the same frequency, wouldn't that indicate an issue with the left and right walls? 106hz translates to like 126in, which is almost exactly the distance from the speaker to the side wall..
Can you post the REW MDAT?
Old 11th September 2020
  #7
Quote:
Originally Posted by thethrillfactor View Post
Can you post the REW MDAT?
Yeah when I get off work I'll grab it. I guess I'll need to post the pre and post subwoofer recordings.
Old 12th September 2020
  #8
Quote:
Originally Posted by thethrillfactor View Post
Can you post the REW MDAT?
Here's the final MDAT for left, right, and both speaker measurements. Let me know what you find.
Attached Files
File Type: mdat Final.mdat (5.83 MB, 2 views)
Old 12th September 2020
  #9
Quote:
Originally Posted by johannburkard View Post
Zoomed out this much it doesn't look bad. But what does the spectrogram say?
I'm not 100% sure how to read a spectrogram, so maybe you can help
Attached Thumbnails
Turned My Living Room Into My Control Room-both-speaker-spectrogram.jpg  
Old 12th September 2020
  #10
Speaker symmetry looks good to me. Very loud desk reflection -- are your speakers on stands?

Spectrogram shows that the decay above 200 Hz is too long and that your treatment is not effective enough below 50 Hz. On the screenshot, you should see a flat(-ish) line from the low mids upwards.

Decay times might be too long for serious work.
Attached Thumbnails
Turned My Living Room Into My Control Room-rt60.jpg  
Old 12th September 2020
  #11
Quote:
Originally Posted by johannburkard View Post
Speaker symmetry looks good to me. Very loud desk reflection -- are your speakers on stands?

Spectrogram shows that the decay above 200 Hz is too long and that your treatment is not effective enough below 50 Hz. On the screenshot, you should see a flat(-ish) line from the low mids upwards.

Decay times might be too long for serious work.
Yeah I had mentioned these issues in the original post. I knew the decay times would be the next job to tame above 200. This post was just to show the progress so far in terms of spl and first reflection management, which seems to be ok.

Speakers are on stands and decoupled, but very close to the desk, almost negating the benefits. Unfortunately due to the layout of the living room I have to have them about 44in apart, which doesn't quite give them enough room to miss the desk at the midpoint between my head and the speaker.

I did do one test with an acoustic panel on the desk and flattened out all the ruffles above 500 and killed one of the etc spikes under 3ms, but I can't obviously put an acoustic panels on the desk. I just did it to see which etc spikes were due to the desk.
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