[davejcb]

Hi all,

I'm considering building these traps (figure 3) for my corners... What I'm wondering is if the entire space behind the front panel should be filled with insulation, or only a panel? That image isn't clear to me.

I also want to build these, I was wondering if these can be used in corners providing the back is sealed?

Thanks!

[davejcb]

Never mind, found this.

Delete thread at will, I should have searched more. Sorry!

[Ethan Winer]

Dave,

> Never mind, found this. <

Yeah, if you skip over the silly name calling and focus on the discussion of panel traps, the explanations in that thread are helpful.

I'll just add that wood panel traps are more appropriate for large rooms, and less so for smaller rooms like those the size of a bedroom. For small rooms I generally recommend thick, dense rigid fiberglass placed across the corners instead of wood panel traps. How big is your room?

--Ethan

[davejcb]

Here is a layout of the room. I was thinking 3 corners trapped, except the stairs.

Here is a picture of that corner I just took. Pardon the mess. How do you think that part of the room will affect things? The rest is pretty much square.

On the corner traps do the tops and bottoms need to be sealed like on the panel traps? And why is it exactly they work better in bigger room?

Thanks!

[Ethan Winer]

Dave,

> Here is a layout of the room <

For a room that size you'll get fine results with thick, dense, rigid fiberglass mounted across the corners. That is also a lot easier, and a lot cheaper, than building wood panel traps.

> On the corner traps do the tops and bottoms need to be sealed like on the panel traps? <

No, you just slap 'em up.

> And why is it exactly they work better in bigger room? <

Great question. Traps made of rigid fiberglass work very well when mounted across the corners. But in a large room, even when all the corners are treated, you still have large areas of bare surface. More to the point, you need to cover 10-30 percent of the room's surfaces with traps to make a big improvement in the low end response. In a small room with a regular ceiling height, covering all the corners treats a fairly large percentage of the room. In a large room, especially with high ceilings, covering all the corners treats proportionally less of the total surface. So now you still need traps on the walls. And when mounted flat on walls, panel traps absorb low frequencies better than rigid fiberglass (unless you make the fiberglass really thick).

--Ethan

[Rob Babcock]

How thick is real thick?  I'm just curious.  I've been a bit preoccupied lately, haven't had the chance to experiment with any of the cool stuff I've learned here.  

[Russtafarian]

I'd like to experiment with building some traps from sheets of compressed/rigid fiberglass.  Where can I find it?  Home Depot or other such stores?

In addition to mounting traps in wall/ceiling corners and junctions, what about other areas?  In one corner of my 20x16x8 room is a five drawer filing cabinet with about a four inch gap between it and the wall.  Would there be benefit to filling that gap with a 4 inch thick sheet of compressed fiberglass?

[Rob Babcock]

Your Lowes/Home Depot stores don't usually carry it.  You usually have to buy it from a dealing in insulation or HVAC, I think.  Ethan would know.

[davejcb]

Try this. Check for local dealers.

[davejcb]

I understand that the bigger room will need more trapping, but which trap is actually more efficient? Would only having fiberglass in the corners be as good as only having panel traps in corners, assuming my room?

Also, which would be more suitable? Would using the first one kill too much midrange, only using it in corners?

3.0 PCF (48 kg/m3) Plain 4" (102 mm)

125 250 500 1000 2000 4000hz

.95 1.11 1.17 1.07 1.07 1.06

6.0 PCF (96 kg/m3) FSK 2" (51 mm)

125 250 500 1000 2000 4000hz

.77 .50 .72 .58 .53 .41 .60

[Ethan Winer]

Rob,

> How thick is real thick? <

Three or four inches.

--Ethan

[Ethan Winer]

Dave,

> which trap is actually more efficient? <

Traps based on rigid fiberglass are more efficient when mounted across corners and spaced away from the wall (or ceiling). Wood panel traps are more efficient when mounted flat on a surface. Since large rooms have proportionately more flat surface area versus corners than small rooms, wood panel traps make sense in large rooms. But there's no reason you can't have both types in one room. My home recording studio has 17 wood panel traps, plus 20 panels and traps based on rigid fiberglass.

> Would using the first one kill too much midrange, only using it in corners? <

Maybe - it depends on how many of them you have. And this is another important difference between the two trap types. A wood panel trap reflects mid and high frequencies, where fiberglass does not.

--Ethan

[davejcb]

Let's say 3 corners, 3 panels mounted vertically - which one would you use?

[Ethan Winer]

Dave,

How big is your room? If it's a room the size you find in a typical home, I'd use rigid fiberglass rather than bother building panel traps.

--Ethan

[davejcb]

Size is in the first few posts. I meant which of those two fiberglass choices would you use?

[Red Dragon Audio]

Size is in the first few posts. I meant which of those two fiberglass choices would you use?

Howdy Dave,

I have read this whole post and it looks to me like the rigid fiberglass boards in the corners would work best in your room.  Plus you will have the ability to move them around a bit or add more or take away panels as you feel the sound gets more dialed in.

I was thinking you could put three in the corners where the walls meet the ceiling.  Then maybe put one or two in the corners of the walls and try a couple on the center of a couple of walls.  The nice thing with the fiberglass panels is that you can experiment more quickly with the sound by moving things around a bit.


I read you are going to paint the room.  First get the sound setup right with all the panels, then take it all down and paint.  THis way you avoid messing up your new paint except where you know are going to hang your panels.

[davejcb]

I read you are going to paint the room. First get the sound setup right with all the panels, then take it all down and paint. THis way you avoid messing up your new paint except where you know are going to hang your panels.

Good idea!

I guess I'll set it up how you mentionned, just need to figure out which fiberglass to order now... I spoke to a Knauf rep quickly, he's calling me back tomorrow, apparently there's a sound absorption-specific panel they carry. I'll post what he sends me.

[Ethan Winer]

Dave,

> I meant which of those two fiberglass choices would you use? <

For maximum low frequency absorption I'd use 705.

--Ethan

[davejcb]

Dave,
For maximum low frequency absorption I'd use 705.

Ethan,

Have you ever tried fiberglass from other sources than Owens-Corning? Just looking at 705-FRK versus the 6 PCF FSK 2" from Knauf, the numbers look better on the latter:

705-FRK, 2":  .60 .50 .63 .82 .45 .34 .60

6.0 PCF FSK 2": .77 .50 .72 .58 .53 .41 .60

Or is there more to it than that, such as different measuring methods, etc? Numbers for 705 are off this page. Doesn't mention how they measured, while Knauf mentions 1/3 octave? Both show the ASTM C243, Type A mounting mention.

To me the Knauf looks better on paper. Am I missing something?

Thanks for your time!

[Ethan Winer]

Dave,

> Have you ever tried fiberglass from other sources than Owens-Corning? <

No, but small deviations are statistically insignificant, and are mainly because the tests were done in different labs. This is not to say that one brand is not better than another. But I'd go by price only, unless the stated difference is 20 percent or more.

--Ethan