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Advise on room acoustic treatment (REW attached)

player1024

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Mar 26, 2023
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Room is almost a square (9x11 feet), with one side being a long doorway opening, to a larger room, therefore no right wall really.
Right wall 5.5 feet away from Mic, with 3 windows.
Mic is almost positioned in the middle of the room.
There is pretty much no left wall as you can see.
All graphs are 1/12 smoothing. Recorded with ECM-8000 mic, using its calibration file.
Speakers are 1 foot from the wall behind them and around 8 feet from the wall in front of them (treated with panels most of it).

3 questions:

  1. My waterfall at 450ms shows like i got some 100hz and 200hz decaying at 50db SPL, I presume that's an issue right?
  2. Also why do I have such a deep @ 1kHz on my SPL?
  3. Where shall I place basstraps and how much more paneling and where shall I place those too?

Thank you!

Screenshot 2023-03-25 215533.png



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ozzy9832001

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Feb 19, 2023
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I'm assuming the baseline was about 80dB? I see a massive peak around 140 probably about 12dB higher than baseline due to corner adding to the peak. I'm assuming you have an 8' ceiling or close to it.

Your room dimensions aren't that far off from mine at 9.5x11.5x8'. Though your decay is much better than mine. I suspect the missing wall has a lot to do with that, as the sound just keeps going. 1khz dip could be a reflection from ceiling, sidewall or floor causing destructive interference. The wavelength for 1khz I think is like a foot. So, if you in the middle of the room, it maybe from the back wall. Is there any toe in on the speakers?

I'm curious how is your stereo image? Missing the sidewall sometimes creates problems with it and you need a panel or something to simulate a wall.

If you get bass traps, save yourself the time and money and get the thick corner ones. Front and back corners. Start there. If the measurements are good after that, then you may not need further treatment, otherwise, I'd start with the ceiling to wall corners. 2x4ft traps would probably be great.
 
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player1024

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I'm assuming the baseline was about 80dB? I see a massive peak around 140 probably about 12dB higher than baseline due to corner adding to the peak. I'm assuming you have an 8' ceiling or close to it.

Your room dimensions aren't that far off from mine at 9.5x11.5x8'. Though your decay is much better than mine. I suspect the missing wall has a lot to do with that, as the sound just keeps going. 1khz dip could be a reflection from ceiling, sidewall or floor causing destructive interference. The wavelength for 1khz I think is like a foot. So, if you in the middle of the room, it maybe from the back wall. Is there any toe in on the speakers?

I'm curious how is your stereo image? Missing the sidewall sometimes creates problems with it and you need a panel or something to simulate a wall.

If you get bass traps, save yourself the time and money and get the thick corner ones. Front and back corners. Start there. If the measurements are good after that, then you may not need further treatment, otherwise, I'd start with the ceiling to wall corners. 2x4ft traps would probably be great.
Thank you for the prompt reply.
I do have a toe-in, pretty much equilateral triangle from the listening position and the mic was positioned slightly more forward from the triangle vertex as recommended.
What would be the best way to objectively assess my stereo image?
Baseline is around 75-80 db SPL, yes.
Do note that the wall behind the listening position is treated with 0.5" panels (not foam) - would that explain the fairly homogenous curve above @ 2-6kHz and the mild dip from >6kHz?
Could you recommend the 2x4ft traps you mentioned? (links appreciated!)
 

ozzy9832001

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Thank you for the prompt reply.
I do have a toe-in, pretty much equilateral triangle from the listening position and the mic was positioned slightly more forward from the triangle vertex as recommended.
What would be the best way to objectively assess my stereo image?
Baseline is around 75-80 db SPL, yes.
Do note that the wall behind the listening position is treated with 0.5" panels (not foam) - would that explain the fairly homogenous curve above @ 2-6kHz and the mild dip from >6kHz?
Could you recommend the 2x4ft traps you mentioned? (links appreciated!)
GIK Acoustics makes some very good products. You can browse their website for their full range of products. Since your missing the left wall that sort of acts like a bass trap.

I use these in my room though https://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/

I would recommend with the range limiter...so you don't over absorb the mids and highs.

They are very thick and designed for corners and things of that nature. Space may not allow for them in your place. Though I highly recommend them in the corners if you can a) afford them or b) have the space. You could save a lot of money if you are handy and can make them yourself.

I have 4 of these in the 2 corners of my office (can't put them in the other 2) and 2 above the speakers (8ft span). My decay times still a bit high sub 100hz but part of that is because my external walls are concrete.

Gauging stereo image is just something that you hear. Not sure you really can test it. I suppose hypothetically if both speakers are playing the same thing it would be at its best, but that's not always the case depending on how they are setup and how the room interacts with the sum of both speakers based off placement, etc. Missing the sidewall sounds like it could force it to be left sounding because there are no sidewall reflections from the right speaker. If it's far enough from the sidewall it wouldn't matter as much.

Do the vocals sound centered? If you shift your head slightly left or right does the "image" shift with it?
 
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