John Sayers' Recording Studio Design Forum Archive

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

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.

I've sent you all the info you need in an e-mail.

Paul

I just got it. Thank you so much!

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!

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

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.

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

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!

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

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.

Hello all

Bit newbie on this forum but it impressed me when I've read few thread so far.
I'm building a big listening room in my basement (36' x 20' x 7,5'). I know, I miss ceiling height but I can't do much to change that.

I'm reviving this thread for 2 questions

1- is there somebody that went from let say: between 16 to 24 inchs with 10inch airgap rearwall broadband absorber to those acoustic hung DIY panel?
comments or better yet, measurement?

2- I'm from Canada and we have a product that seem similar to Hemasote 440. it is lighter and serve the same purpose. only come in 3/4" thick tho. Sonopan.
https://sonopan.com/

Any though on this should I go the hanger option.


Thanks,

etalon90 wrote:Hello all

Bit newbie on this forum but it impressed me when I've read few thread so far.
I'm building a big listening room in my basement (36' x 20' x 7,5'). I know, I miss ceiling height but I can't do much to change that.

I'm reviving this thread for 2 questions

1- is there somebody that went from let say: between 16 to 24 inchs with 10inch airgap rearwall broadband absorber to those acoustic hung DIY panel?
comments or better yet, measurement?

2- I'm from Canada and we have a product that seem similar to Hemasote 440. it is lighter and serve the same purpose. only come in 3/4" thick tho. Sonopan.
https://sonopan.com/

Any though on this should I go the hanger option.


Thanks,

Homasote is not needed or even advisable (despite the numerous claims on this forum of it being some sort of acoustic gold dust) the way which the hangers works means that the core should be as dense and damped as possible. 18mm (~3/4") plywood or chipboard with a bitumen dead sheet (or similar) stapled to it, wrapped in fibre will work much better as a wave guide.

You want them to be as wide and long as possible, if you want them to have a significant effect for low frequencies then we're talking 1.2m wide and as long/high as your room.

Angeline90 wrote:

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

There is a paper done on the hangers, it tells you how to approximate the frequency range of absorption, I've posted this numerous times:

https://www.academia.edu/27385637/A_Stu ... GqXDhZmvhk

the reason they need to hang is so that the vibrations don't transmit into the room shell.

the reason for the insulation is because that's what does the absorption, not the panel core itself. The panel cores act like wave guides. there is also a small horn effect. But, the panel cores without insulation have almost no effect on reducing decay rates, will only offer some reflection control via deflection.

the hangers are only part of the whole system, they work best when used in front of a diaphragmatic inner shell.

they work in a similar manner as lined ducts, or baffled silencer boxes, just on a larger scale and for a different purpose.

the best book on the subject is Philip Newell's "Recording Studio Design" where they are mentioned in various chapters as well as a whole appendix written on them. But, the linked paper will tell you all you need to know.

Thanks for the quick reply.

I'll build few prototype for my first side reflection and go from there.
3/4'' chipboard it will be

If they work great, I'll start the rear wall project.