I realize this question has many answers and many opinions. But here goes anyway:

There seemed to be some agreement that using framed panels, stuffed with insulfsheild, linacoutic, etc covered in fabric and spanning corners, either wall-wall, or wall-ceiling was an effective (for the price) bass trap and that generally, the bigger the spanned and enclosed space the better.

In my installation I can basically make the wall-ceiling traps as big as I want, and I've tentatively put some up that have a 2 foot wide face with 18 inches on the wall and ceiling behind the panel. I've seen most people use traps more like 6-10 inches on face, I wonder if I'm overshooting the goal with mine. There is 1.5 inch insulshield in the panel, but I have so much left over I could fill the whole cavity with it.

Also, the trap has an open end facing into the room, since it doesn't run the whole length of the wall. Would it be better to cap that end, or run more (maybe smaller) traps the rest of the length of the wall and in the wall-wall corners (I can't run the 2 foot wide size on the ceiling in other places because of the recessed lighting.)

I can take photos tonight if that's helpful. Thanks in advance.

There seemed to be some agreement that using framed panels, stuffed with insulfsheild, linacoutic, etc covered in fabric and spanning corners, either wall-wall, or wall-ceiling was an effective (for the price) bass trap and that generally, the bigger the spanned and enclosed space the better.

In my installation I can basically make the wall-ceiling traps as big as I want, and I've tentatively put some up that have a 2 foot wide face with 18 inches on the wall and ceiling behind the panel. I've seen most people use traps more like 6-10 inches on face, I wonder if I'm overshooting the goal with mine...
What is your goal? Depending on the finished room size, you will have a hard time reaching the ideal depth for controlling all low frequency room modes. I am talking here about treatment depth measured in feet, not inches! One often has to resort to electronic compensation for very low frequencies. Again, this depends on your requirements.

Regards,
Terry

generally, the bigger the spanned and enclosed space the better.
Yes, exactly.

I've seen most people use traps more like 6-10 inches on face
That is woefully inadequate. If you can make the faces three feet wide, then you'll really be on to something useful. :D

I could fill the whole cavity with it.
Perfect!

--Ethan

I used floor to ceiling panels, with a corner bass trap behind them. I angled the panels inwards from the side wall to the screen wall.

http://www.tekmil.com/theartek/pages/IMG_7009.htm
Above is the raw panels before covering in velvet and satin.

http://www.tekmil.com/theartek/pages/IMG_7195.htm
Above is after covering and also showing the saide wall acoustic panel continuation, where I have made panels either side of the first row seating, those panels are just above head height when seated. This has taken care of the reflection points.

The panels are moveable nearest the screen, so I can access the original power outlets etc. that are behind the one on the left.

You can see the angles better in this shot:
http://www.tekmil.com/theartek/pages/IMG_7197.htm

The bass traps behind these panels are 'corner' traps. Floor to ceiling traingles of glass wool, covered in poly batting to eliminate dust.

Distance from the actual corner of the room and my front speakers is over 1 meter. The result is fantastic, I have heard nothing but positive comments about the sound quality. So I know that this setup works well.

Exposing more face will provide more absorbtion and decay time control. Making them thicker for the same exposed area will allow them to perform better down deeper.

Realistically, you'll get some control down into the 50's with treatments if they're big enough and placed properly (not all issues come from corners...) but below that, as Terry said, EQ is your friend. If you do the speaker, seating, and sub placement to minimize nulls, you can EQ out the peaks that are left after treatment.

Bryan

Exposing more face will provide more absorbtion and decay time control. Making them thicker for the same exposed area will allow them to perform better down deeper.

So: Thicker solid face pieces = better deeper control, and stacked edge pieces = better absorbtion over a higher range? Interesting trade-off, I guess it really depends on the particular room which is the better choice doesn't it.

That is woefully inadequate. If you can make the faces three feet wide, then you'll really be on to something useful.


Quote:
I could fill the whole cavity with it.


Perfect!

I'm a little confused, I thought the value was in creating the largest feasible enclosed open air space as a cavity, but you're also saying to fill the cavity with more absorbing material. Are those two conflicting suggestions or am I missing something?

So I'm hearing (pun intended) that there's a point below which it doesn't much matter how much treatment you do, you need an EQ to achieve a flatter response (at least in rooms like most people are building). Just the improvement from treating the first reflection points was huge, now everything else is (to me at least as an unsophisticated listener) gravy.

I used floor to ceiling panels, with a corner bass trap behind them. I angled the panels inwards from the side wall to the screen wall.

TekHouse, those panels look great! I really like the curved/stepped effect of those panels in the corner!

It has done wonders adding that curve stepped thing. I had them straight earlier and noticed big changes once I came up with the step/curve arrangement.

I also have the possibility of leaning them IN at the top if I need to as well, to create a very asymmetrical space at the front..So far I have not needed to. :)

So: Thicker solid face pieces = better deeper control, and stacked edge pieces = better absorbtion over a higher range?

The more bass trapping the better. Always.

I thought the value was in creating the largest feasible enclosed open air space as a cavity

No, air is not a bass trap. Fiberglass is. In some cases air can replace some of the fiberglass, but the air isn't actually doing anything. It's just a by-product of spacing the fiberglass out from the wall a bit where it's more effective.

--Ethan

No, air is not a bass trap. Fiberglass is. In some cases air can replace some of the fiberglass, but the air isn't actually doing anything. It's just a by-product of spacing the fiberglass out from the wall a bit where it's more effective.

Thank you. That makes sense. Well, I guess when I get home I'll be cutting up a lot of fiberglass. Mmmm, tasty delicious fiberglass.

Thank you. That makes sense.

I should have posted this yesterday:

http://www.ethanwiner.com/acoustics.html

See the section Optimizing the air gap which explains the role of an air gap in much more detail.

--Ethan