That is what I thought. Until I cut up 6 boxes of 2" corning 703 and found a night and day improvement.
Corner Bass Traps - Always beneficial?
- Thread starter edorr
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That is what I thought. Until I cut up 6 boxes of 2" corning 703 and found a night and day improvement.
Don,
Everyone seems to agree on it. But when I see that a bunch of Corning 703 in the front corners seems to ameliorate a null at 45Hz by about 7 dB and spectacularly raise the level between 20 and 70 Hz I start questioning the established knowledge.
Hi Bill,
I have 4 Mondo Traps (bass only) on the rear wall. 1 each in the corners, 1 each behind the speaker suspended off the wall 4" with U brackets RTraps can supply. The rear wall ceiling has mini traps and the side walls (on stands) and ceiling first reflection points use micro traps which absorb mid to highs and not bass. Behind my listening chair are 3 Mondo full range absorber traps mounted off the wall using the U brackets.
I have 4 Mondo Traps (bass only) on the rear wall. 1 each in the corners, 1 each behind the speaker suspended off the wall 4" with U brackets RTraps can supply. The rear wall ceiling has mini traps and the side walls (on stands) and ceiling first reflection points use micro traps which absorb mid to highs and not bass. Behind my listening chair are 3 Mondo full range absorber traps mounted off the wall using the U brackets.
Guys, not everyone is talking about the same bass trap execution here. Some are referring to thick panels hung diagonally in corners forming a triangular air pocket behind the panel whereas others are referring to what are called 'super chunks' where the entire corner is filled up with material, no air gap. The latter is really the way to maximise corner bass trap performance and probably why eddor is seeing better results than others.
The issue I have with the 'super chunks', is they also affect high frequencies. I am seriously looking at Realtraps, because I do not want to impose any additional high frequency absorption, while aiming to tame modal frequencies.
I have experimented with placing a ton of absorption in the corners. And although the technique does indeed help bass performance, it also sucks much of the life and energy out of the sound.
I have experimented with placing a ton of absorption in the corners. And although the technique does indeed help bass performance, it also sucks much of the life and energy out of the sound.
Have you considered covering the bass corner chunk with a material that is reflective at higher frequencies? This approach has been used by ASC for a long time!
Lee
Lee, what material is ASC using to cover their panels? I have a sample set of their fabrics, and it looks like pretty standard stuff to me. Is there anything between the fabric and the corning they are using. I have not build the panels to cover my corner traps yet, so I would be interested to find out what is the best material I could use. Not sure there is much high frequency absorbtion going on in the corners behind my fully enclosed speakers, but that is another story.
I haven't torn apart a tube trap, but I heard it is some type of foil layer underneath the fabric. Putting the foil around 1/2 of the circumference of the trap allows users to rotate the trap for the best balance of reflection/absorption.
Lee
They use Guilford FR701 acoustic fabric - you can see them at http://www.acousticsciences.net/c-swatch.htm.
As far as I know you should seal the corning traps with a very thin material - these fibers are not very healthy.
Sorry, I was not clear. I am not arguing any of this; I see the same improvement in my system/room and it is indeed significant and very worthwhile even at LF if you have enough treatment (that is one reason why my room is treated). My concern is that nulls due to cancellation can be quite deep, as in 20 to 30 dB or more, and those are very hard to treat. I have seen and measured treatments in the 3 - 6 dB or so range, maybe up to 10 dB with a lot of treatment; more than that IME requires resonators or active structures. The depth and width of the null is very dependent upon the room, including walls and other materials as well as what's in it. I suspect there are still a few deep nulls in most of our systems, including mine, but as higher-Q nulls than tend to be not heard since they are so narrow.
Note that edorr has also stacked a lot of material in the corners, providing a deeper (thicker) absorber than most use, and helped kill some of the "build-up" of sound energy that often happens in the corners. In fact, IMO it is a good argument for going with such a scheme. My room also uses much thicker absorbers in the front corners (about 12" IIRC) but just stacking triangles is a much cheaper and more effective way to go. It would be interesting to see the change if the triangles were pulled out the corners just a little, maybe 6", to provide a little gap.
Aside: The biggest drawback to a lot of absorbers such as I have is that HF's are also attenuated. For me that is not a problem as (a) I wanted to kill the back wave from my dipoles to limit comb effects in my small room, (b) I am tolerant of the "studio" sound with few reflections, and (c) it provides very precise imaging. In a larger room, or if I was worried about it, I would use or add membranes to retain HF reflections whilst still having LF absorption. Or, if I was less cheap, I would add diffusors, perhaps in front of the absorbers to provide a little more "airy" feeling in the room.
FWIWFM - Don
p.s. You can buy Corning material with a foil membrane or not, or add your own, to increase HF reflections (i.e. limit HF absorption). IN the primordial past I helped build custom frames for mineral wool and we would then play with the facing to vary the absorption.
Thanks. I have a set of swatches for this fabric. Did not realize it had special acoustic properties. I ordered some cotton canvas that I was planning to paint in the color of my walls. Sounds like a doomed strategy .....
The fabric can affect HF absorption; what you choose depends upon the sound (and look) you want to achieve. If you've ordered fabric, any fabric, try it and see -- you may like it!
For $2200 + shipping you can get 8 realtrap megatraps, that give you the same volume of absorbing material + whatever secret sauce they add to their traps.
My room is asymetrical and has some opening space in the back. I suspect very little HF ever makes it to the front wall corners of my room.
Yes, it would interesting. As it is my understanding that an air gap behind an absorber, will significantly extend the low frequency effectiveness of the same absorber. More so than filling in the same amount of gap with additional absorption material.
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