Am I on the right path?

[pratul]

Hoping folks can help me pick the right approach to addressing some of the room mode issues that I am unable to resolve by moving the speakers/subs or the listening position. I have pretty serious dips at around 60 Hz and between 100 - 130 Hz that correspond to the modes predicted by the models (see attached). I have included two models for the two lengths (my room is kinda - sorta "L" shaped). The entire room has an inch thick acoustic panel covering the lower half of all the walls. These I think are managing the decay times for the higher frequencies pretty well.
For the 60Hz and 100 - 130 Hz dips and the long decay at the lower frequencies, I was thinking of adding 6" bass traps near the back wall and the front corners. I am also thinking of adding 2" panel to cover the window and also to reduce the reflection from the ceiling. I show the location where I am thinking of placing them in the attached diagram.

Am I thinking of the problem and solution the right way? Am I on the right path or would you suggest a different approach?

Thanks for your help!

 

[Sonnie]

It's going to be very difficult to acoustically treat that area below 130Hz... and 6" panels won't do the job either. The size panels/traps you'd need for this would be ridiculously large and require serious testing. Your best and easiest route for your subs is PEQ filters... or something that can auto-eq the lower frequencies. Not sure if the ARC in your Anthem will do the job, but it's worth a try.

You might even consider reading Floyd Toole's book on room acoustics... studies are proving that no absorption is preferred ... or even diffusion if you have a dedicated room.

 

[pratul]

Thanks @Sonnie ! I have to get that book!
So, you are saying I should look at diffusion instead. Any one in particular, given my situation ?
Also, what do you think of the waterfall charts? Do you see any issues there?
I have early reflection from the front speakers and think they are from the ceiling and the window. Adding some absorption there should help, right? Thanks!

 

[pratul]

Also, the graphs I have above are after using ARC. They were even worse before

 

[pratul]

@Sonnie Thought I'd add the impulse responses for the front speakers. The reflections before 20 ms is what I am hoping to address with adding absorption on the ceiling and to cover the window.

 

[Sonnie]

Unfortunately I'm not the one to interpret the charts, so maybe some of the more knowledgeable ones will chime in.

However... floor and ceiling absorption is what I understand to be acceptable, although there are several I've seen using diffusion on the ceiling as well.

There are those in the camp of stating absorption can give a tighter and more focused image, while diffusion gives a larger soundstage without doing too much damage to the imaging. Naturally it all depends on the speakers and the room, so result can vary. Testing can be expensive this scenario, which is why I decided to build my own diffusion panels.

 

[pratul]

Thanks @Sonnie
That is an impressive diffusion panel! Have to read up on that. Love your theater BTW.

PS: The link to the slideshow under "AV Showcase" goes to http://www.cedarcreekcinema.ws instead of .me. You might want to fix that. the .ws site gets a phishing warning.

 

[Sonnie]

Thanks @Sonnie
That is an impressive diffusion panel! Have to read up on that. Love your theater BTW.

PS: The link to the slideshow under "AV Showcase" goes to http://www.cedarcreekcinema.ws instead of .me. You might want to fix that. the .ws site gets a phishing warning.

Thanks ... and I updated that link to .me

I need to update all of my photos. As soon as I get the new diffusion panels installed, I'll take more photos... hardly anything is the same.

 

[ddude003]

@pratul It looks like you are headed in the right direction... I would agree with Sonnie about needing more base trapping in the corners... Instead of 6" base traps, I would suggest you look at something like the Gik Soffit Bass Traps with a Range Limiter... These bass traps are 17" thick... Floor to ceiling in the front at a minimum... Or you could go with the 6" in thick absorbers and fill the space behind them with something known to absorb low frequencies...

A combination of physical absorption and diffusion will make a big difference... And make additional minimal adjustments with EQ easier...

 

[pratul]

Thanks @ddude003 !

 

[AJ Soundfield]

The 60hz dip is too narrow to be audible and you really ought to move the mic and measure in a few locations, not just one. See what happens with the upper dip. Can the subs be moved?

 

[AJ Soundfield]

studies are proving that no absorption is preferred ... or even diffusion if you have a dedicated room.

For 2 ch yes, for HT (MCH), not quite. Now of course, it is advised to "furnish" the room first. But Toole does not advise "no treatments" for HT. It can be helpful if used appropriately.

cheers

 

[crossrh]

Audioholics has some great videos they just posted a few weeks ago, with Anthony Grimani discussing this topic. Very informative, and easy to digest.
Rick

 

[pratul]

The 60hz dip is too narrow to be audible and you really ought to move the mic and measure in a few locations, not just one. See what happens with the upper dip. Can the subs be moved?

Thanks for you reply @AJ Soundfield !
I tried moving my subs a bit (a lot actually) more today and was able to get rid of the 60 hz dip. Thanks! The position isn't ideal esthetically but the sound is a lot better.
I also placed some temporary absorption at the front corners ( just some mattress foam i had lying around). Running ARC improved it a bit more and it sounds much better. I am definitely going to add some bass traps in the front corners.

Thanks!

 

[pratul]

Audioholics has some great videos they just posted a few weeks ago, with Anthony Grimani discussing this topic. Very informative, and easy to digest.
Rick

Thanks @crossrh ! I will look them up.

 

[CAAudiophile]

Hi, generally speaking, it is easier to control a spike than a dip, in another way to look at graph issues is how wide is the dip frequency wise ... if it is a narrow I won't worry about it.