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 Post subject: Re: Acoustic hangers
PostPosted: Thu Oct 01, 2020 4:52 pm 
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Location: Wales, UK
Skai_Penalva wrote:
Hi everyone!

I'm having trouble finding specific information addressing the angles that hangers should have in a back wall. I've seen some posts mention this but can't seem to find the science behind how the angles of the hangers work. Could anyone please point me in the right direction?

Also, I've seen designs in other posts where the hangers are on the inside wall of the room covered with a breathable fabric, and others that seem to have the hangers inside the air gap between the 2 back walls. Is this correct? Can I place hangers inside the air gap between 2 leafs to achieve proper bass absorption?

I appreciate any information to better understand how hangers work (:


I have a couple of academic papers on hangers which contain a lot of info and data, as well as how to construct them properly. Please PM your e-mail and I will send it to you.

The way that Philip Newell does it is like so:
45 degrees for the rear wall, 10-20 degrees for the side walls, the ceiling hangers should be aimed at the loudspeakers so that only the hangers' leading edges are seen from the point of view of the loudspeakers.

I do not know how well they work in the air gap, but seems like a waste to me. The inner walls would need to be quite lossy in order for that to be useful. They also take up a lot of space... the newell hangers are typically 1.2m wide and 3 or 4m tall (depending on room height). That is a seriously big air gap, in which case the cavity resonance will already be rather low anyway... you'd basically be creating very large membrane traps, and the use of hangers inside them might not be necessary. But, who knows?

Paul

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 Post subject: Re: Acoustic hangers
PostPosted: Sat Oct 03, 2020 6:39 am 
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Joined: Thu Nov 01, 2007 8:44 pm
Posts: 59
Location: Honduras
Hi Paul,

Thank you so much for your reply!

I would really appreciate the info you have on hangers. I'll PM you with my email. That's very kind of you

"The way that Philip Newell does it is like so:
45 degrees for the rear wall, 10-20 degrees for the side walls, the ceiling hangers should be aimed at the loudspeakers so that only the hangers' leading edges are seen from the point of view of the loudspeakers."

- Would you happen to have any pictures showing this? It's a little hard for me to understand in which direction they are angled or aimed. I can't tell which is the leading edge...

I noticed on your studio build post you have hangers on your back wall. Did you cover these with fabric? Are they on the inside of the room? I thought they were inside the air gap.

Also on the ceiling I noticed you did something similar. How are did you cover the ceiling?

I wonder because I see pictures like the following one, and then studios with angled ceilings and back walls but they seem solid, not fabric.


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 Post subject: Re: Acoustic hangers
PostPosted: Sat Oct 03, 2020 4:39 pm 
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I've sent you all the info you need in an e-mail.

Paul

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 Post subject: Re: Acoustic hangers
PostPosted: Sun Oct 04, 2020 12:32 am 
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Location: Honduras
I just got it. Thank you so much!

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 Post subject: Re: Acoustic hangers
PostPosted: Thu Oct 29, 2020 9:50 am 
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Joined: Wed May 13, 2015 1:54 am
Posts: 3
Location: Upstate New York, USA
Hello,

I’m thinking about switching my back wall from 24” of 6000 GFR to hangers.

I have a bunch of Armstrong ceiling tiles that are essentially 1” 703 or 705 with some sort of decorative binder on the front and notched edges.

Could I glue this to homasote 440 to make effective hangers, or should I use thicker less dense insulation like Roxul 60 (I have some of this too).


Thanks!


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 Post subject: Re: Acoustic hangers
PostPosted: Thu Oct 29, 2020 1:14 pm 
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Location: Wales, UK
Grovestand wrote:
Hello,

I’m thinking about switching my back wall from 24” of 6000 GFR to hangers.

I have a bunch of Armstrong ceiling tiles that are essentially 1” 703 or 705 with some sort of decorative binder on the front and notched edges.

Could I glue this to homasote 440 to make effective hangers, or should I use thicker less dense insulation like Roxul 60 (I have some of this too).


Thanks!


It's up to you but I personally would use the less dense stuff...and I would use a denser core such as ply or chipboard instead of the homasote unless weight is an issue.

Paul

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 Post subject: Re: Acoustic hangers
PostPosted: Fri Oct 30, 2020 2:19 am 
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Joined: Wed May 13, 2015 1:54 am
Posts: 3
Location: Upstate New York, USA
Paulus87 wrote:

It's up to you but I personally would use the less dense stuff...and I would use a denser core such as ply or chipboard instead of the homasote unless weight is an issue.


Thanks Paul!

So R-13 and OSB would work better than 703 or Roxul 60 and homasote? Score one for the cheapskates!

To attach the R13 to the OSB, I guess I would just drape the R13 over the OSB and staple fabric around it to keep it in place without compressing.

I’m still on the fence really. Getting kind of burnt out on acoustic testing.


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 Post subject: Re: Acoustic hangers
PostPosted: Fri Oct 30, 2020 3:37 am 
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Location: Wales, UK
Grovestand wrote:
Paulus87 wrote:

It's up to you but I personally would use the less dense stuff...and I would use a denser core such as ply or chipboard instead of the homasote unless weight is an issue.


Thanks Paul!

So R-13 and OSB would work better than 703 or Roxul 60 and homasote? Score one for the cheapskates!

To attach the R13 to the OSB, I guess I would just drape the R13 over the OSB and staple fabric around it to keep it in place without compressing.

I’m still on the fence really. Getting kind of burnt out on acoustic testing.


OSB is ok, chipboard is what Newell recommends. The way I do it is use large circular washers and screws to attach the insulation to the boards, it doesn't matter too much if it compresses a little. As far as I can tell, this is also the way Hidley did it.

If you want to spend a little more then thick Dacron (polyester wadding) can be used either in place of or wrapped over the insulation, which makes working with them a little nicer since it's less itchy and suffocating.

To hang them you could use chains but I have found using eyelet hooks in the top of the cores with another hook in the beam where they are to be hung and then a carabiner to join the two works well, and pretty cheap. This makes them easy to take down if ever you need to.

Paul

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 Post subject: Re: Acoustic hangers
PostPosted: Fri Oct 30, 2020 7:14 am 
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Posts: 3
Location: Upstate New York, USA
Chipboard = Particleboard?

After some googling, it looks like it is the same thing.

I can't find 1/2" particle board anywhere at the big box stores. I guess I could order it from a place that specializes in sheet goods, or I could use 3/4". That would be very heavy. 3/4" 4x8 are $22 USD.

Does the width and rigidity of the panels matter or just the mass? I'd use 1/8" hardboard if it doesn't really matter.

A 4x8 sheet of:
1/8" hardboard weighs 28 lbs.
1/2" particle board weighs about 72 lbs.
3/4" particle board weighs 85 lbs
1/2" Homasote 440 weighs 38 lbs

I could save money by using a combination of materials, since I already have some 8' pieces of 1/2" and 3/4" plywood, MDF, Hardboard, and Melamine.

WTB lab test results with different cores and insulation!


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 Post subject: Re: Acoustic hangers
PostPosted: Thu Mar 04, 2021 7:24 pm 
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Joined: Wed Mar 03, 2021 4:55 am
Posts: 1
mika wrote:
mika wrote:
i still don`t understand the way hangers work.
i another forum i read something about a variable impedance trap.
Is a hanger something like this?
how does it work, and how can you calculate it?
cheers
Mika


I just want to bring it up

Does anyone have technical infos about how Rachat de crédit trésorerie travaux a basshanger work?

Is it just a porous absorber with high destiny?
Why hanging? And when hanging what effekt would be used for absorption?
Why wrap it with insulation? damping vibrations?

Or does anyone know a book about these topic?

Please help me to bring light into the dark.
cheers
Mika

Hello,
I am interested in this answer, how do you think this can be calculated? in relation to the hanger


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 Post subject: Re: Acoustic hangers
PostPosted: Fri Mar 05, 2021 4:33 am 
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Posts: 5010
Location: Old Tappan, NJ USA
technically "hangers" are a type of broadband absorber - the low density fiberboard provides both absorption and waveguide functions. the waveguide effect lengthens the path the energy needs to travel (thus approximating a deeper cavity) while also interfering because of the incident angle on the absorptive nature of the fiberboard. obviously lined cavity and insulation attached to the panels provide velocity absorption, and on the panels also damping action for any resonance.

i have somewhere in my archive some papers that were the results of some limited examination on the details of how all this work - pressure gradients, etc but it's buried somewhere. as far as i know, Jeff Cooper (genius/recording studio designer/acoustician) has a fairly straight forward formula to estimating the effect of these assemblies. he has an excellent book on the overall subject which includes the design. https://www.amazon.com/Building-Recordi ... 0916899004

Homasote Soundboard 440 is the ideal panel product, however, there are not many options to obtain it outside of the North America. similar density products seem to be in short supply elsewhere in the world. sometimes the right fiberboard can be found in older style thumbtack boards or cubicle partitions. also, a dense triple layer 15mm cardboard approximates the mass of the fiberboard but not the gas flow rate.

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