Room Treatment Analysis

[tjcinnamon]

Hi All,

I'm in the process of analyzing my room. I'm looking to see if there would be value in moving around my existing treatments as well as buying new ones.

I have a few constraints:

• Speakers can't be moved due to in-wall speakers and a mounted TV
• The existing GIK "Alpha" Panels are advertised as being diffusion/absorption. In my experience they are not, they are very diffusive and are very absorbent
• The side walls can't have absorption due to then killing the Polk SDA effect (I've tried a number of options there). However, hard diffusion or membrane traps could work on those walls.
• I'm open to moving a bunch of treatments around but have experimented and absorption pretty much diminishes the SDA effect.
• I have subs directly behind the couch for effect. I can level them out pretty good but did not for the attached REW measurements (REW file is zipped)

All of the measurements I took were with all room correction off. Also, I left the subs at the volumes that I will calibrate them at and the measurements may need "align SPL". The room sounds solid but I'm always chasing nirvana... Any advice appreciated.

 

[AdamG247]

You will get improved results by flipping your arrangement. Put your speakers on the longest wall. Less side wall reflections and more room to separate your main speakers. Just a suggestion. In this reversal the whole couch can be situated in the MLP. Your right speaker is jammed in tight and side wall reflections are increased in this situation.

 

[tjcinnamon]

Apparently the MDAT (REW) file is too big. Here's a link:

https://drive.google.com/file/d/19hi8P2RSJx8UhAvygQP7x6qCV8OuTVZG/view?usp=sharing

 

[sam_adams]

Ideally you want all reflections to be -15 dB below the direct sound in the first 20 ms so that they are absolutely inaudible.

Left:

Center:

Right:

For reference (from Everest):

The reflections in the first 2 ms might be from the couch. Drape the fuzzy blanket you have there over the back of the couch and the seat. Double or triple it up for good measure to see if that kills the near reflections. Make sure that you are measuring with the mic placed right where your head will be for the best measurement. Do not be like Khan Noonien Singh; think in three dimensions when it comes to reflections.

 

[tjcinnamon]

Ideally you want all reflections to be -15 dB below the direct sound in the first 20 ms so that they are absolutely inaudible.

Left:
View attachment 251225

Center:
View attachment 251226

Right:
View attachment 251227

For reference (from Everest):
View attachment 251230

The reflections in the first 2 ms might be from the couch. Drape the fuzzy blanket you have there over the back of the couch and the seat. Double or triple it up for good measure to see if that kills the near reflections. Make sure that you are measuring with the mic placed right where your head will be for the best measurement. Do not be like Khan Noonien Singh; think in three dimensions when it comes to reflections.

Dang! I just got that couch and it’s basically above my ears. I have to sit upright to get my head above it. So basically adding a little absorption on the leather by adding the blanket?

I’ll move the mic down. Although it’ll be basically right next to the headrest (hence the name, I suppose). I measured just above the headrest.

 

[sam_adams]

Dang! I just got that couch and it’s basically above my ears. I have to sit upright to get my head above it. So basically adding a little absorption on the leather by adding the blanket?

I’ll move the mic down. Although it’ll be basically right next to the headrest (hence the name, I suppose). I measured just above the headrest.

Remember that the mic is more discriminating than your ears because it doesn't have a brain attached to it. When you remeasure, if the close in reflections are reduced a significant amount, you know where they are coming from and then you can ignore them in future measurements.

 

[tjcinnamon]

Remember that the mic is more discriminating than your ears because it doesn't have a brain attached to it. When you remeasure, if the close in reflections are reduced a significant amount, you know where they are coming from and then you can ignore them in future measurements.

Thank you!

Here are some measurements at precisely ear level. I did them with Room Correction On, Room Correction Off, with an without FDW. I also measured the subs (just in case).

https://drive.google.com/file/d/1ponkA3jm6QaTA_D-QCDD4it-AI94bIFD/view?usp=sharing

 

[Jdunk54nl]

This may be beneficial for you:

tutorial: how to find and treat early first reflections

This tutorial was done in my home, but the same concepts can apply to a car. My home stereo is in an asymmetric room and I have problems with the left and right speakers sounding very different. This disrupts my stereo imaging, is very annoying, and cannot be fixed with DSP. So I examined...

www.caraudiojunkies.com

 

[tjcinnamon]

Remember that the mic is more discriminating than your ears because it doesn't have a brain attached to it. When you remeasure, if the close in reflections are reduced a significant amount, you know where they are coming from and then you can ignore them in future measurements.

I tried it with the blanket and the SDA effect was reduced. So pretty much anything that reduces that effect, I'll live with even if the graphs are worse.

That said, I talked with GIK and they said that my room overall looks very good. I'm going with a pretty inexpensive diffuser option which is their polystyrene 13-root diffusor: https://www.gikacoustics.com/product/gik-acoustics-gridfusor/

I'll try them on the ceiling and the side walls. Hopefully they increase the SDA effect. Otherwise, they may be boxed up until my next build and I can call the room done.