AVS Discussions

Home Theater Construction => Acoustics => Topic started by: bmoney on November 13, 2016, 07:38:09 AM

Title: Bass traps?
Post by: bmoney on November 13, 2016, 07:38:09 AM
whats the true deal with these...I have heard they need to be 4-6' thick to really attack the FR we need that are troublesome?

so what say you?  do chunky corner traps work? 
Title: Re: Bass traps?
Post by: laugsbach on November 13, 2016, 10:38:07 AM
I have a lot of acoustical treatments in my room. The entire front wall is treated with Roxul and 9" of pink fiberglass in each of the front two corners from floor to ceiling. I really like a dead space as I watch 95% movies and 5% music. I have nine 18" subs spread around the space to help with the low frequency response...

The bottom line is it measures very well and sounds very, very well to my ears... :)
Title: Re: Bass traps?
Post by: bmoney on November 13, 2016, 11:13:26 AM
do you have measurements?
Title: Re: Bass traps?
Post by: ellisr63 on November 13, 2016, 06:31:40 PM
I have a lot of acoustical treatments in my room. The entire front wall is treated with Roxul and 9" of pink fiberglass in each of the front two corners from floor to ceiling. I really like a dead space as I watch 95% movies and 5% music. I have nine 18" subs spread around the space to help with the low frequency response...

The bottom line is it measures very well and sounds very, very well to my ears... :)
I agree... I have 3" of Roxul on our front wall, plus 4" on all side, and ceiling 1st reflection points. We did our rear wall with 9" of Roxul, ans also made triangles for the rear corners floor to ceiling. Then we used Denim for out soffets all around the room. I enjoy the way everything sounds including the music. I find the instruments are floating is space more with a room that is closer to dead than live.
Title: Re: Bass traps?
Post by: bmoney on November 14, 2016, 05:08:30 AM
my room is pretty dead too ...was listening to music in there yesterday and man it sounds good!

just wondering about the bass traps
Title: Re: Bass traps?
Post by: ellisr63 on November 14, 2016, 08:41:44 AM
my room is pretty dead too ...was listening to music in there yesterday and man it sounds good!

just wondering about the bass traps
I believe bass traps will make the bass tighter...or at least they did in my room.
Title: Re: Bass traps?
Post by: bmoney on November 14, 2016, 08:58:25 AM
thats not the question :) its i heard that they need to be at least 4-6' thick to hit the below 100Hz that is the most troublesmoe
Title: Re: Bass traps?
Post by: ellisr63 on November 14, 2016, 09:10:45 AM
thats not the question :) its i heard that they need to be at least 4-6' thick to hit the below 100Hz that is the most troublesmoe
We made ours 9" thick on our rear wall, plus we have corner traps, and soffet traps that are 2' deep. It def made a difference in our room, and I have zero regrets on making them.
Title: Re: Bass traps?
Post by: ShadeRF on November 14, 2016, 12:41:40 PM
They made a big difference for my room. The bass was very muddy and rumbly before. After treating the room the bass is much tighter and refined sounding.
Title: Re: Bass traps?
Post by: laugsbach on November 15, 2016, 07:04:36 AM
do you have measurements?

I do...I did a quick look using my OmniMic after installing the new AVR because it had a different version of Audyssey vs. my old Onkyo AVR. The FR looked good and I didn't save it because I usually wait 30 days after an AVR change before I fire up REW to really dial it in. I have changed laptops since my last saved measurement and will fire up the old lap and DL the picture of the FR for you...
Title: Re: Bass traps?
Post by: laugsbach on November 15, 2016, 07:09:34 AM
I find the instruments are floating is space more with a room that is closer to dead than live.

Good point! I have quite a few concert Blu-ray titles with hi-rez audio and it feels like a live performance! When I do listen to music, I like 2 channel hi-rez audio...the room fills with sound and quite a few times I am checking the AVR to make sure only two speakers are playing!  :)
Title: Re: Bass traps?
Post by: ellisr63 on November 15, 2016, 09:17:31 AM
Good point! I have quite a few concert Blu-ray titles with hi-rez audio and it feels like a live performance! When I do listen to music, I like 2 channel hi-rez audio...the room fills with sound and quite a few times I am checking the AVR to make sure only two speakers are playing!  :)
So very true... You don't know how many times I have had to get up, and check to make sure the surrounds are not on when playing my ripped SACDs!
Title: Re: Bass traps?
Post by: seplant on November 24, 2016, 08:43:23 PM
I agree... I have 3" of Roxul on our front wall, plus 4" on all side, and ceiling 1st reflection points. We did our rear wall with 9" of Roxul, ans also made triangles for the rear corners floor to ceiling. Then we used Denim for out soffets all around the room. I enjoy the way everything sounds including the music. I find the instruments are floating is space more with a room that is closer to dead than live.

Do you have any photos of your wall treatments?  I'm also curious as to what type of Roxul you used. 
Title: Re: Bass traps?
Post by: ellisr63 on November 24, 2016, 09:59:45 PM
Do you have any photos of your wall treatments?  I'm also curious as to what type of Roxul you used.
All I have are the pics of my theater... The bass traps are covered with GOM material. The Roxul we used was R60, and R80 Rockboard. It is green in color and is 2" or 3" thick, and is semi hard. It is fireproof too, which is another plus. I believe it came in in bundles of 6 or 8(2' x'4') sheets. Our first reflection points are 2 layers of 2", back wall bass traps are 9" thick, front wall behind our screen is 2" thick...all Roxul R60/R80 Rockboard.
Title: Re: Bass traps?
Post by: Shawn Byrne on November 25, 2016, 10:28:51 PM
whats the true deal with these...I have heard they need to be 4-6' thick to really attack the FR we need that are troublesome?

so what say you?  do chunky corner traps work?

Yes, they do work.  They work because the pressure along the boundary (and greater along the juncture of two or more boundaries) is the greatest.  Fiberglass absorbers work better with air movement, and since the maximum air pressure along the boundary indicates little or no movement.  How they work is that at a given depth, the air is still moving before it reaches zero velocity.  The effectiveness is not at the boundary but at some distance away from the boundary.  Therefore the pressure is reduced.  Does it eliminate resonance altogether at the boundary?  No.  Pressure still exists, but the trap may be reduced relative to the room's low frequency SPL where it no longer is audible in relation to the direct sound.  However, what frequencies they are most effective at is the question.  The thicker they are, the lower the frequencies they may effect.  It is more effective to engineer a bass trap due to its much larger size and low frequency impact on resonating frequencies.  The frequencies that are most problematic will be a function of your room dimensions, and are often referred to as room modes. 
Title: Re: Bass traps?
Post by: bmoney on November 26, 2016, 04:51:43 AM
thanks I know what room modes are.

and you proved my point...traps do NOT help with the most troublesome frequencies
Title: Re: Bass traps?
Post by: Shawn Byrne on November 26, 2016, 08:53:15 AM
Not true, they actually do.  Just to what degree...that's the question, and that is completely room dependent.
Title: Re: Bass traps?
Post by: ellisr63 on November 30, 2016, 09:38:40 AM
Here is a fairly quick way to see if bass traps will help in your situation... Go to a local store and pick up some bundles of fiberglass insulation. Once you get them home, put the complete unopened bundle in your corners...even along your rear wall and then test it out. I bet you will hear a difference...don't forget to rerun your room tune software (after saving your original tune). If you are not happy with the results you can just return the unopened bundles. I know it is a bit of a hassle to do it this way, but it will def let you know if in your situation it will do what you want. Looking forward to hearing your results. :)
Title: Re: Bass traps?
Post by: bmoney on November 30, 2016, 09:54:27 AM
Here is a fairly quick way to see if bass traps will help in your situation... Go to a local store and pick up some bundles of fiberglass insulation. Once you get them home, put the complete unopened bundle in your corners...even along your rear wall and then test it out. I bet you will hear a difference...don't forget to rerun your room tune software (after saving your original tune). If you are not happy with the results you can just return the unopened bundles. I know it is a bit of a hassle to do it this way, but it will def let you know if in your situation it will do what you want. Looking forward to hearing your results. :)

love it !  I may try it out...now if it DOES work...would I just enclose the bundle behind a AT panels?
Title: Re: Bass traps?
Post by: ellisr63 on November 30, 2016, 10:06:27 AM
love it !  I may try it out...now if it DOES work...would I just enclose the bundle behind a AT panels?
I have 3 bundles of Roxul sitting in between my front 3 channels behind my AT screen in addition to my 3" Roxul wall. I stumbled upon the using bundles when I was reading up on bass traps. From what I read the plastic will not effect the bass, but also will not allow certain high frequencies to be absorbed so it is a win win situation in a lot of scenarios. On our rear wall I was worried about too much damping so I covered the whole rear bass trap in a thin black rubber sheeting, and then made GOM false wall fabric panels to cover it all up.
Title: Re: Bass traps?
Post by: AVSCraig on October 16, 2019, 01:24:03 PM
thats not the question :) its i heard that they need to be at least 4-6' thick to hit the below 100Hz that is the most troublesmoe
I'm in the process of getting bass traps from GIK, so I'll let you know the results. While I am getting two corner Tri Traps, and two 7.3125” thick Monster bass traps, most of them will be 244 Bass Traps which are 5.25" thick - 

https://www.gikacoustics.com/product/gik-acoustics-244-bass-trap-flexrange-technology/

 (https://www.gikacoustics.com/product/gik-acoustics-244-bass-trap-flexrange-technology/)I also have some ceiling diffusors coming too. 
Title: Re: Bass traps?
Post by: TRainH2O on October 16, 2019, 06:01:05 PM
I'm in the process of getting bass traps from GIK, so I'll let you know the results. While I am getting two corner Tri Traps, and two 7.3125” thick Monster bass traps, most of them will be 244 Bass Traps which are 5.25" thick -

https://www.gikacoustics.com/product/gik-acoustics-244-bass-trap-flexrange-technology/

 (https://www.gikacoustics.com/product/gik-acoustics-244-bass-trap-flexrange-technology/)I also have some ceiling diffusors coming too.
I think their main US warehouse is about 60 miles from me. I've heard a lot of great things about their products.
Title: Re: Bass traps?
Post by: AVSCraig on October 16, 2019, 07:15:17 PM
I think their main US warehouse is about 60 miles from me. I've heard a lot of great things about their products.
I got three of their acoustic panels a few years ago and hung them at the main reflection points. Regular guests to my theater sat down to watch a movie, and after a few minutes, one of them turned to me and said " did you get new speakers " ?  :o  They had no idea I'd hung those panels - I had to point them out later. I found that extremely interesting. Should be even more interesting installing 15 bass traps - the ones in front behind the red velvet curtains have range limiters, the ones in back will have scatter plates. And a 16' x 2' row ( two rows  of 8' x 2' really - one on each side of the ceiling peak ) of diffusion panels on the ceiling right where I can see speakers using the mirror trick.

It's going to be a serious acoustic makeover !
Title: Re: Bass traps?
Post by: AVSCraig on October 17, 2019, 08:20:05 AM
Here is a great article regarding bass traps - https://ethanwiner.com/basstrap_myths.htm (https://ethanwiner.com/basstrap_myths.htm)