[Syrah]

So I'm awaiting a big order of OC 705 to make some more corner bass traps.

As with my prior designs, I plan to use a 6 mil plastic sheet between the burlap cover and the insulation.

My question is this, should the plastic sheet be glued (ie. 3M 77 spray for eg.) to the insulation or should it just float?

Thanks.

[Big Red Machine]

Whatever makes it easier to create your form-factor. Don't overthink this. Floor to ceiling 12 inches or better will really help. More is better in the corners and other locations can be beneficial as well once you see what your room modes are. I see no need for the plastic myself. If in the corners behind the speakers there is very little high frequency with box speakers (but still a lot of energy building up there). If in the rear corners, maybe, but I have never bothered with adding the barrier. I am not sure I could measure the difference unless they were first reflection points. YMMV

[mcgsxr]

The only reason I used plastic with my Roxul safe n sound traps faced with 705 is to keep the S&S together behind the 705!  It helped retain the otherwise sag prevalent stacks of Roxul.

For cutting and stacking 705 I would agree you can skip that step if it helps move the project forward.

[Syrah]

Thanks guys.  I'm going with the plastic sheeting for two reasons, based on prior replies from the experts,

i. it makes the trap absorb lower down; and,
ii. it prevents the room from being overly deadened.

I'm just not sure whether the sheet should be glued to the first layer of 705.

[drummermitchell]

For sure there's a reason for that membrane (plastic or whatever)especially if  the corner traps can dig lower,
and especially keeping the room from having the life sucked out of it.
Talk to Glenn(GIK)or Ethan(Realtraps).
I'd rather ask them and find out as they have been doing this for yrs,and it's FREEEE.
Talk to those who know that's my motto or your going to be unhappy.                                                                                                    There is a reason why the use a membrane for corner trapping and not reflection areas.
Ask people who are in the KNOW,otherwise you have fly by night,midnight autos and everything else.
Get the most top notch knowledge you can find,works for me .

[JLM]

I like the idea of using a plastic layer, simply to prevent fiberous materials from getting into the air.  Years ago we laughed about asbestos, so who knows what the future will reveal.

[mcgsxr]

Agree on the fibers.  I put cloth on both sides of my DIY traps for this reason.

[JWL.GIK]

Hi guys!

Most of the successful membrane bass traps I've seen glue the membrane to the absorbent material under it. So that's what I'd be inclined to do.

And yes, if you do a membrane correctly, it will both increase the bass absorbed and decrease the treble absorbed. Both of these things are very useful for corner bass traps.

Also, I would make the traps more than 12" wide where possible. 24" is good and quite convenient in terms of build. Bigger is better all else being equal.

[jk@home]

When I did my corner bass traps, I used some of that landscape fabric between the fiberglass and the burlap. It has a slight reflective quality, and helps hold in the fibers. Left it out of the front and sides on all the other panels, but use it in the back in lew of burlap.

Seems to me years ago I read Real traps used craft paper, instead of plastic.

[DTB300]

I use the Acoustical Cotton in my GIK Clone DIY Traps.  No worries about fibers then...

I also use RPG BAD and BAD ARC panels, so no need for a membrane in front of my Bass Traps.