FRK/FSK alternates

[RCM - Ronan]

If I have plain OC 705 are there alternates to FRK that can be used to cover one side to get a low end absorption response similar to 705FRK? I read one place that even plastic bags would do the trick. Any thoughts?

[dredbird]

I have the same question.

One thread mentions posters as suitable.

Are there any kinds of readily available paper that would work, such as something from an Office Supply store? I have a bunch of 67lb cardstock already.

[dredbird]

By "posters" I mean wall posters, not forum members

[Ethan Winer]

Originally Posted by rcm

I read one place that even plastic bags would do the trick. Any thoughts?

Yes plastic film, or thin cardboard, or paper posters etc.

--Ethan

[jwl]

yeah, any thin material like that is likely to work. The key parameters are mass, and stiffness.

Uh huh huh, that's what she said.

[dredbird]

So how about a fabric covering that has those qualities already, like suede or something? Or the shiny fabrics we'd otherwise stay away from?

[Glenn Kuras]

Originally Posted by dredbird

So how about a fabric covering that has those qualities already, like suede or something? Or the shiny fabrics we'd otherwise stay away from?

Sure those could work, but it might be best to test them before hand.

Glenn

[jmvega]

Does the foil side go to the front or to th back, or does it depend on the application? If the later is the case, when should it go to the front and when should it go to the back.

Thanks

[Glenn Kuras]

Always to the front.

[panimal]

I have an FRK related question so hope this isn't a thread hi-jack

In terms of using an FRK substitue i.e. Posters, paper card etc. Will it do to place it over the front front of the fabric of a trap?

In my traps there's a 20mm airgap between the rocksilk and where the muslin rests on the frames. I suspect i'd have trouble gluing paper to the rocksilk directly and worried if i do a bad job it will affect absorption properties -but will give it a go if it's the best option.

traps i built are here:
Small room conversion plans

[Glenn Kuras]

Attaching it to the front of the fabric is fine.

[panimal]

thanks Glenn

[ejsongs]

so which of the 3 options will work the best?

poster paper, plastic (are we talking cling wrap or garbage bags), or card board or some sort of foil

oopps...i guess that is 4 items.

if one to the resident experts would rank them that would be great.

ej

[Glenn Kuras]

It would be hard to say without testing, but as the material becomes more rigid and thicker it will reflect lower frequencies.
Just a note, you don't want to put any kind of facing on the panel(s) when placing them in early reflection points.
What Are Early Reflection Points. SPOTLIGHT:Bob Ebeling - Revolution Studio

[ejsongs]

but if you had to choose....which would you use?

ej

[Ethan Winer]

I'd use thin plastic, like the stuff garbage bags are made from.

--Ethan

[Millo 3.1]

Originally Posted by Ethan Winer

I'd use thin plastic, like the stuff garbage bags are made from.

--Ethan

Excellent...like the dark ones? Taking note, I'll give it a shot...

[ejsongs]

Originally Posted by Millo 3.1

Excellent...like the dark ones? Taking note, I'll give it a shot...

to clarify i think this poster is asking whether to use the plastic from lawn garbage bags (black or brown plastic) or the indoor kitchen type plastic (White)?

also to ethan i ran across a design of your where you use 1/4 or 1/8 in plywood as your facing...how do you think that would work in with a 6" panel of 703/705 with 2" air gap behind?

lastly, i made some 2in 703 panels with 2" air gap for my early reflection points but it seemed to pull out too many highs an made the room feel uncomfortable. glenn said not to use any facing for the reflection points...any suggestions?

ej

[Ethan Winer]

Originally Posted by ejsongs

to clarify i think this poster is asking whether to use the plastic from lawn garbage bags (black or brown plastic) or the indoor kitchen type plastic (White)?

I can't imagine the color matters!

to ethan i ran across a design of your where you use 1/4 or 1/8 in plywood as your facing...how do you think that would work in with a 6" panel of 703/705 with 2" air gap behind?

Wood panel bass traps are totally different from fiberglass panels. Panel traps need to be built as shown.

i made some 2in 703 panels with 2" air gap for my early reflection points but it seemed to pull out too many highs an made the room feel uncomfortable. glenn said not to use any facing for the reflection points...any suggestions?

Yes, my suggestion is to live with the absorbers for a while and see if you get used to the increased clarity.

--Ethan

[ejsongs]

hey guys

i have a quick question about applying a membrane such as plastic or frk to fiberglass or rockwool.

should the membrane be glued to the front of the panel or overlayed on the front and glued to the back of the panel so that the membrane can move more on it's own? obviously fabric would go over everything.

which way would give the best results?

thanks in advance,

ej

[Ethan Winer]

Yes, glued is the way to go.

--Ethan