# How to tell if fabric is AT



## raZorTT (Jan 17, 2008)

Hi,

Living in Australia means GOM is a little harder to come by. I've only heard of one place in fact that sells it (thanks cinema mad) so I was wondering how would I audition other fabrics to see if they are suitable for treatments and potentially in front of speakers?

A couple of posts here have said if you can breathe through it, or if you don't detect any sound changes with the fabric next to your ear then it should be fine?

Any thoughts? 

Cheers,
Simon


----------



## thewire (Jun 28, 2007)

The breath test works fine for when you are shopping for any kind of fabric other than those that are marketed as AT such as Muslin or GOM. I do think I read a member was able to find Muslin in Australia for a reasonable price. You could also measure and look for a high frequency roll-off. It's what amounts to a small difference for sound for most people and it is quite often that commercial theaters do not equalize for such a thing. There is no rule for how AT it must be but dependent on the speaker it can sometimes make a difference. For example if your tweeter is a silk dome tweeter these are already going to sound smooth to most people and often adding AT cloth in front of it will make them sound less ideal to the inteded design by the manufactor. Which crossover it will use can also have an added effect but that will usually only be something to think of if say they are using ones that are larger in size.


----------



## raZorTT (Jan 17, 2008)

Thanks thewire,

Maybe i'll be better of doing the area infront of the speakers in speaker cloth and looking for a GOM/Muslin for the treatment areas. I'm off to a fabric supplier at the end of the week and am hoping to find something I can use. Wish me luck!

Cheers,
Simon


----------



## bpape (Sep 14, 2006)

The cloth in front of treatments isn't all that critical quite honestly. You just don't want something that won't pass air or it will reflect high frequencies.

On the other hand, cloth in front of speakers is extremely critical. I wouldn't do muslin in front of a speaker. GOM or a cloth specifically designed for speaker grille use (you know, the typical, stretchy, thin, black, poly stuff) would be the only thing I'd use.

Bryan


----------



## raZorTT (Jan 17, 2008)

OK thanks Bryan!


----------



## cinema mad (Jan 28, 2007)

I no Spot light in geelong vic sell 1.5 mt loom width Black speaker grill cloth at A reasonable price $13au mt I think, if you are interested I can give you the spot light product code.. They also ship Australia wide....

Cheers...


----------



## raZorTT (Jan 17, 2008)

Hey Cinema Mad,

If you could that would be fantastic. I'm off to Spotlight in Queanbeyan so being armed with the product code would be a huge help!

Cheers,
Simon


----------



## cinema mad (Jan 28, 2007)

Hi Simon,
The spotlight speaker cloth is as follows,

Name: Loudspeaker, PLU: 1283123" Width is 1.5mt and price is $12:95au

If your store does'nt have it you can have the Geelong store ship it to you, If you ask for the Manager Scott and tell him that Jason said that he you would look after you with the Loud Speaker Cloth...

Cheers Mate...


----------



## Prof. (Oct 20, 2006)

Simon,

While you're at Spotlight, you might want to have a look at a material called "Black Poly Stretch"..
This is the material I used on my screen wall..
It's an open weave stretch material..1.5M wide and only cost $6.99/M. when I bought it..


----------



## raZorTT (Jan 17, 2008)

Thanks for the info guys! 

Much appreciated.


----------



## raZorTT (Jan 17, 2008)

Picked up a metre or so of the loundspeaker material on the weekend from spotlight. Was a little different to what I had been expecting. It's not really your classic speaker grill, it's really hard to explain, It seems to have a bit of a shimmer? Or maybe i'm just looking at the wrong side :T

Unfortunately I couldn't get my hands on the black poly stretch, will have another look next time i'm out there. The place is such a mess I don't know how they find anything! The trick might be to get there as they open.

No luck finding something for walls like GOM yet either :scratchhead:. Might need to concertrate my search more towards office fabrics than clothes.

Cheers,
Simon


----------



## raZorTT (Jan 17, 2008)

Are there any materials that I should be concerntrating on?

So cotton, wool, acrylic or polyester? Or is it all about the weave?

Simon


----------



## raZorTT (Jan 17, 2008)

Sort of answering my own question here. I jumped onto the GOM website and see it's a plain weave made out of 100% polyester. It doesn't mention the thread count or alternatively the GSM. 

Can anyone from the US answer that?

Cheers,
Simon


----------



## bpape (Sep 14, 2006)

Not really - but you can't just judge by those things. I can tell you that there are a lot of thin, easy to blow through fabrics that will definitely impact HF absorption - and others that don't look like they would be (like GOM), that do basically nothing to speakers behind them.

Bryan


----------



## cinema mad (Jan 28, 2007)

That is A good point Bryan, and that is the risk some of us unknowingly take when using A cheap fabric to cover fiberglass used for first reflecton treatments :yikes:...

Though any fabric has some sort of effect good or bad when used to cover the absorbtion membrane some more than others....

Cheers....


----------



## bpape (Sep 14, 2006)

Yeah. For panels, it's not a big deal. For that, the blow-through test is just fine.

Bryan


----------



## raZorTT (Jan 17, 2008)

Thanks for clarifying guys!

For the screen wall and in front of the speakers i'll be using a black speaker cloth.

Trying to find something for the panels that looks good is going to be my challenge based on the fabrics I have looked at so far :T


----------



## raZorTT (Jan 17, 2008)

Just an update on my fabric adventure.

Went back to spotlight on the weekend to look for potential fabrics.

Ended up coming home with a couple samples, a polyester interlock and a polyester suit fabric. The suit fabric is a little more dense than the interlock, but has a much more interesting texture.

I plan to make up a couple small panels so I can stretch and attach the fabric to and do some testing in between myself and a speaker to see if I can notice a sound difference.

Cheers,
Simon


----------



## Prof. (Oct 20, 2006)

raZorTT said:


> Ended up coming home with a couple samples, a polyester interlock and a polyester suit fabric. The suit fabric is a little more dense than the interlock, but has a much more interesting texture.


Polyester Interlock was the one I originally used on my screen wall..
The thing I liked about it was that you can stretch it a fair bit, which opens up the weave..

Is the suit fabric also stretch.?


----------



## raZorTT (Jan 17, 2008)

Hey Prof,

That's exactly what I thought when I grabbed it 

The suit fabric does stretch a bit, but not as much as the interlock does.
I much prefer the texture/look of the suit fabric, so am hoping it will be fine for the side/rear walls.

I'm trying to get some speaker grille from the guys I bought my speakers off for the screen wall. It's a little less shiney/furry than the loudspeaker from spotlight. Mind you with the lights down at 50% or less most the time, probably no one would notice 

Cheers,
Simon


----------



## raZorTT (Jan 17, 2008)

Would two layers of GOM in front of my main speakers have an effect on the sound?

I'm thinking of getting black GOM for my screen wall and am considering a 2.37:1 screen. I'm thinking of having masking panels on each side (covered in black GOM) on a track for 16:9 material. So when watching 2.37 the panels would slide away but be in front of the L&R speaker.

I assume putting twice the amount of material in front of the speakers will have some effect on the sound transmission.

Cheers,
Simon


----------



## bpape (Sep 14, 2006)

Yes. It will have an impact on the higher frequencies. If you could do some sort of snap in panel as opposed to a sliding panel, you'd not have the problem. 

Bryan


----------



## raZorTT (Jan 17, 2008)

Thanks Bryan,

Back to the drawing board 

Cheers,
Simon


----------

