Debating options for Bass Traps

[pratul]

Affect of the bass traps on the left and right channels. This is before any EQ.

 

[ddude003]

@pratul, Nice work so far... May I ask how tall are these? And did you do any kind of strike plate or MLV?

 

[pratul]

@pratul, Nice work so far... May I ask how tall are these? And did you do any kind of strike plate or MLV?

They are 88" tall with a 16" x 16" profile. The outside facing sides have 8" of rockboard 60 each. This leaves a 8" x 8" area of air behind the insulation.

I did not use a strike plate or MLV on these. I decided to leave them broadband.
Next I want to add two more similar bass traps for the back corners using the pink fluffy stuff. That should even things out a bit more.
I will look into limp membrane absorbers if f I have any bumps and dips remaining after that.

 

[Sonnie]

The square apparently work better than the triangle... or it could just be your room and listening position combo.

Looks very promising.

My corner bass traps from GIK (fully stuffed) had zero effect on the frequencies below 80Hz (subwoofers).

 

[pratul]

The square apparently work better than the triangle... or it could just be your room and listening position combo.

Looks very promising.

My corner bass traps from GIK (fully stuffed) had zero effect on the frequencies below 80Hz (subwoofers).

Yes, I was pleasantly surprised by the results. The music sounds so much better now and the dialogs are so much more clearer. I'm loving my theater now

 

[Mike-48]

It removed a lot of the peaks and valleys and smoothened the response overall.

I am impressed at how much the bass traps filled in the nulls around 40 and 80 Hz. I'm sure reverb time has improved, too, and with it, overall clarity. Congratulations on a nice job!

 

[pratul]

Quick update on my experiments with bass traps. The graphs above showed the improvements I got by adding two vertical traps on the front two (wall to wall) corners. Encouraged by the results, I added one more trap to the back right (wall to wall) corner. That helped a little bit more. Adding another trap on the back right corner did not produce any incremental improvement. I them tried a horizontal trap in the front, behind the center speaker. That didn't do much either. I then moved it to the back wall (floor to wall) this showed some improvements. My last test was to move it to the back wall to ceiling edge. That worked the best. The graphs below show the incremental improvements to the frequency response.
My next step is to try moving the subs around again to see if I can find a better spot now that the room dimensions have changed a little. Hopefully, I will be able to improve it a bit more.
The traps are as follows:
Front: 16" x 16" x 88" filled with 6" of Rockwool 60 on the exposed sides.
Back Vertical: 13" x 20" x 88" filled completely with unfaced R-30 fiber glass insulation.
Back Horizontal: 13" x 20" x 91" 4" of rockwool 60 on the exposed sides and the remaining volume filled with R-30 fiber glass insulation.

Left Channel:

Right Channel:

Difference in the FR when I moved the horizontal trap from the floor to ceiling:

Hope you find these details useful.

 

[Mike-48]

Congratulations on your results. They are quite significant improvements.

 

[ddude003]

It looks like you have made some nice progress on your journey... Would you care to tell us a bit about the changes of the sound to your ears?

 

[pratul]

It looks like you have made some nice progress on your journey... Would you care to tell us a bit about the changes of the sound to your ears?

I very happy with the way the room sounds now. Earlier the dialogs/vocals used to get muddy when I increased the bass and the bass was very boomy. Now the dialogs/vocals are crystal clear and the bass is awesome. The sound is much more pleasing now. As soon as my work is done, I am in the theater listening to music and them watching Game of Thrones. My wife hates it because I will play the music loud and everything upstairs starts shaking

 

[ddude003]

It will be fun to see you progress with sub placement and some eventual eq... Are there some diffusers in your future?

 

[pratul]

It will be fun to see you progress with sub placement and some eventual eq... Are there some diffusers in your future?

I am researching diffusers and limp membrane absorbers. Have not figured out what ranges to target yet. The Limp membrane is easier, I think I will target the 40hz dip with that. However, they are very sensitive to the rigidity of the "box" that the specs of the limp membrane. Hopefully, I will hit the nail with the first one I make For the diffuser, I think I might target the 900Hz to 2.5KHz range. Will see what my research determines.

 

[pratul]

I moved one of the subs around this weekend to see if I could find a better location after all the bass traps where installed and I did find one. So, in summary the improvements I saw with the bass traps were as follows:

Then I found a better location for one of the subs and that improved the overall response further:

And finally the total improvement from the entire exercise:

With these changes I am quite happy with the overall Frequency responses for the front speakers.

Now on to improving the impulse response. I have a lot of reflections that need to be tamed.

 

[ddude003]

Oh, Wow... That is quite an improvement @pratul... Nice work... Watching for your next steps...

 

[Sonnie]

It looks like moving the sub really made a significant difference.

 

[BenToronto]

SRW1000 said "I have four JTR Captivator 1400 subs in my theater room, but still want/need to add bass traps. Having four solid concrete walls may be a contributing factor."

Must be lots of theatres in basements. Ordinary dry-wall walls absorb large amounts of bass energy. But concrete and there various forms of "cinderblock" much less.[/QUOTE]

 

[BenToronto]

Here you go. The dimensions of my theater are on the top of the image below.

Thanks for data. How do the calculations compare to your mic or listening experience? Might be worthwhile to sit in your listening chair and test some of those tones individually to see which (if any) boom.

 

[pratul]

Thanks for data. How do the calculations compare to your mic or listening experience? Might be worthwhile to sit in your listening chair and test some of those tones individually to see which (if any) boom.

They have improved quite a bit, even according to my wife who hasn't seen any of the graphs

 

[SRW1000]

SRW1000 said "I have four JTR Captivator 1400 subs in my theater room, but still want/need to add bass traps. Having four solid concrete walls may be a contributing factor."

Must be lots of theatres in basements. Ordinary dry-wall walls absorb large amounts of bass energy. But concrete and there various forms of "cinderblock" much less.

[/QUOTE]
My theater is actually on the ground floor, not the basement. It's ICF construction, so the walls are 6" thick concrete, 2.5" of EPS foam, and then 1/2" drywall. I wasn't sure how much of the bass would be absorbed by the drywall, since some would pass through, bounce off the concrete, and then some more get absorbed passing through the drywall again. If I had to guess, not much is lost.