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 Post subject: Acoustic hangers
PostPosted: Wed Apr 29, 2009 5:53 am 
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Joined: Fri Mar 06, 2009 12:17 am
Posts: 25
Location: Borculo, Netherlands
Hi John,

Maybe I'm blind 8) but I can't find any information about your acoustic hangers...???

What dimensions are they and what kind if wood and wich kind of insulations(fibreglass or rockwool) etc.etc.

I was planning some in my new studio:
viewtopic.php?f=1&t=11766

I have enough space left and right on the back wall to place hangers but I'm not sure which dimension and how many? I need trapping from 60 till approx 260 hertz

Can you help me John??

Thanks in advance and regards from Holland,
Mic


Last edited by micmic on Sat May 02, 2009 8:47 pm, edited 1 time in total.

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 Post subject: Re: Acoustic hangers
PostPosted: Wed Apr 29, 2009 8:20 am 
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Joined: Mon Jan 27, 2003 12:46 pm
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Location: Australia
This should help

Attachment:
HANGERS.jpg


Attachment:
hangers.skp


You do not have the required permissions to view the files attached to this post.


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 Post subject: Re: Acoustic hangers
PostPosted: Wed Apr 29, 2009 4:09 pm 
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Joined: Fri Mar 06, 2009 12:17 am
Posts: 25
Location: Borculo, Netherlands
Thanks you so much John.

I hope I can get Homosote in the Netherlands.....
Type of isulation is not importend? So I can use Rockwool or fibreglass?


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 Post subject: Re: Acoustic hangers
PostPosted: Wed Apr 29, 2009 7:16 pm 
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Location: Australia
Homosote is a soft fiberboard. It's the board they use for notice boards and often comes with one side painted white so you can mount it on the wall and stick notices on it with drawing pins. :)

and yes - you can use rockwool or whatever you've got ;)


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 Post subject: Re: Acoustic hangers
PostPosted: Wed Apr 29, 2009 7:48 pm 
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Joined: Thu Apr 28, 2005 5:18 am
Posts: 195
Location: germany
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


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 Post subject: Re: Acoustic hangers
PostPosted: Wed Apr 29, 2009 8:22 pm 
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Location: Netherlands
micmic wrote:
Thanks you so much John.

I hope I can get Homosote in the Netherlands.....
Type of isulation is not importend? So I can use Rockwool or fibreglass?

It's like those green underlay panels for (wood/laminate) flooring.. :)


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 Post subject: Re: Acoustic hangers
PostPosted: Thu Apr 30, 2009 4:18 am 
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Joined: Fri Mar 06, 2009 12:17 am
Posts: 25
Location: Borculo, Netherlands
Many thanks John and Ro.

Ro: I just finished a floor with the green boards under it, these boards are only 100x50 cm, so to small. And I seen to many of them now, still have green dots in my eyes. :mrgreen:
I gonna use soft board instead(Dutch = zachtboard)I'll hope that's good too.


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 Post subject: Re: Acoustic hangers
PostPosted: Thu Apr 30, 2009 4:22 am 
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Zachtboard is perfect :)
stay cool, stay green


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 Post subject: Re: Acoustic hangers
PostPosted: Sat May 02, 2009 8:50 pm 
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Joined: Fri Mar 06, 2009 12:17 am
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Location: Borculo, Netherlands
Thanks John and Ro.

I made the hangers and now waiting for the 2.5 cm Rockwool.

I replaced the link in the start of this post with the good one..... :?


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 Post subject: Re: Acoustic hangers
PostPosted: Wed May 13, 2009 9:22 am 
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Joined: Thu Apr 28, 2005 5:18 am
Posts: 195
Location: germany
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 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


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 Post subject: Re: Acoustic hangers
PostPosted: Wed May 13, 2009 9:52 am 
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Mika - I know of no reports or articles explaining how the hangers work.

The only explanation I know of is that each hanger has it's own resonant frequency and when it's note is formed in the room it resonates in sympathy and the insulation dampens the resonance. How true that is I have no idea :)


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 Post subject: Re: Acoustic hangers
PostPosted: Wed May 13, 2009 9:20 pm 
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Posts: 195
Location: germany
Hi john

Thanks for your reply.

So when its a resonating pannel, it must be possible to use any kind of wood or other materials, not just soft fiberboard!?
In this case the kg/m² gives the resonantfreq ?

At the SAE Site is written, that big pannels are for low freq, and small for mid. freq. How can this be, when the same material, with the same kg/m² is used?

Another point is, that when we talk about resonance, it must be a tuned absorber. I can`t feel good with using a tuned absorber, when i don`t know the tunig freq. :roll:

I see you used this hangers often, so do you have any testdata about it?

I will not belive that YOU just plan the bassmangement in a room with more luck than proper calculations :shock:

So please share your secrets in this subject.

cheers
Mika


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 Post subject: Re: Acoustic hangers
PostPosted: Wed May 13, 2009 9:33 pm 
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mika - I wrote the SAE site you mentioned - again I state I have no science on this, and as far as I know no one else does.


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 Post subject: Re: Acoustic hangers
PostPosted: Wed May 13, 2009 9:41 pm 
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Location: germany
OK Thanks. :)

When there is no testdata, i will think about a way to make them by myself in a free time.

Anyobody here with sugestions how to test it, to get the best data as possible?

I think this will be intresting for alot of people :wink:

cheers
Mika


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 Post subject: Re: Acoustic hangers
PostPosted: Thu May 14, 2009 7:36 am 
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I seem to recall similar comments from Eric Desart on another forum, about there not being much research on hangers, and the little bit there is being inconclusive. If I recall correctly, the general consensus on that thread was: "Nobody has really done much science on them, but we all build them because they work and the room sounds good". Or something like that.

It just goes to show that acoustics is still partly about art and experience, even though there is also a lot of science about it.

So the mystery continues: Everyone agrees that they work, but nobody really knows much about how or why, in terms of solid numbers and solid science... And the stuff that IS known about them by folks like John, has been earned by years of hard work and real-life experience, so they keep most of what they know under wraps, for obvious reasons!

Maybe hangers would make a great subject from some smart student of acoustics, looking for a thesis subject...

- Stuart -

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