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Author Topic: Ideas behind some unusal Basstrap types  (Read 2454 times)

Constantin

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Ideas behind some unusal Basstrap types
« on: May 07, 2009, 08:14:59 pm »

Hi Smile
Since i`m still ill , i have to much time to think about acoustical things, and do some research.

There are two types of Basstraps where i can`t find any usefull information about the pricipal of absorption and how to tune/calculate them.

First i want to to go to the Acoustic-hangers which are often discussed in John Sayers Forum.
http://www.saecollege.de/reference_material/audio/pages/Low% 20Frequencies.htm#hang

Theay are made from soft fiberboard wraped with insulation.
Since soft fibreboard is a porous aborbant material with a high gasflow resistance, it is possible that it is just a porous absorber. At the other hand this pannel is hanging with ropes whichh is a indicator that it is a kind of resonating pannel.
At the SAE site they say tht the bigger the surface of the hanger, the lower the absorbant freq. But they don`t talk about thickness, mass or something simmilar!?
So maybee the pendulum effect is used for absorption??
But there is also no information about the rope length, which would give a information about the tuning.

So do somebody know how this trap is working, ang how i can calculate it?

The second one is a traptype which Thomas used in darius Studiobuild.
He called it variable impedance trap.
I thougt about the way it works, espacialy because he said this is a tuned trap.
It`s confuseing for me, because it looks like it is just insulation in special thickness with some air between, which gives alot of impedancejumps between the layers.
I hope Thomas can explain the idea behind this trap, and give some information about the construction. Razz

I hope you can help me to learn a bit more about these traps, and help me to use my "OFF-Time" in a useful way.

cheers
Contantin

Thomas Jouanjean

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Re: Ideas behind some unusal Basstrap types
« Reply #1 on: May 08, 2009, 04:03:13 pm »

Constantin wrote on Thu, 07 May 2009 19:14

Hi Smile
The second one is a traptype which Thomas used in darius Studiobuild.
He called it variable impedance trap.
I thougt about the way it works, espacialy because he said this is a tuned trap.
It`s confuseing for me, because it looks like it is just insulation in special thickness with some air between, which gives alot of impedancejumps between the layers.
I hope Thomas can explain the idea behind this trap, and give some information about the construction. Razz



Constantin,

I must again insist hat the plans posted in Darius's thread are NOT the real plans. They are doctored, hence things are missing or changed. Reverse engineering this room based on what you see there will be very misleading. I'm sure you understand that neither the client or I wish to make the real plans available: those designs are very expensive and I do not like to display my work too much. There are no pictures of the traps and membrane systems as well - this was all kept well under the radars by Darius. Only ER treatment can be seen.

The main idea behind the traps is in the name though. It's a complex mix of membranes, porous materials and air buffers. Think about what changes in impedance VS freq can bring to the table. It's true it is part broadband, part tuned.

Sorry, I'm not willing to tell much more than that - this type of info is confidential.


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franman

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Re: Ideas behind some unusal Basstrap types
« Reply #2 on: May 09, 2009, 01:16:35 am »

IOW, he could tell you, but then he'd have to kill you (along with the rest of us)... Here Here.. forum participants please understand that the professional acoustic designers who participate are making a living by SELLING acoustic designs. We are all willing to discuss the principals and give a certain amount of free advice in the interest of advancing general knowledge about what we do.

It IS NOT a black art, or voodoo. It is science (hopefully combined with a liberal does of design sensibility), but we can't really give away the whole show.... this is how we make a living, so please understand and respect the line that I believe Thomas has elegantly illustrated.

Cheers...

FM
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Bill_Urick

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Re: Ideas behind some unusal Basstrap types
« Reply #3 on: May 09, 2009, 06:36:59 am »

franman wrote on Sat, 09 May 2009 01:16


It IS NOT a black art, or voodoo.



Sure, Franman. Whatever you say.

How come every time you guys go somewhere to do some "acoustic" work, several goats and chickens wind up missing?

Rolling Eyes
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Constantin

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Re: Ideas behind some unusal Basstrap types
« Reply #4 on: May 09, 2009, 07:28:38 am »

Thanks for your replies


I know i alwas ask for valuable information. The reason is, that i want to understand the big picture.
I have alot of respect for your work, and that is the reason i ask YOU and not in the overnight expert forums, where the standart answer is: " put basstrpas in the corner" (it`s not against ethan!!!!! i like ethan!!!!!!)

I want to clarify my questions at this point:

My intrest goes to the funktion a trap works. For example when i ask for a Helmholtz, i search for a info like: a helmholtz couples a roomvolume to the resonatorvolume.................. and so on.


But for a Basshanger for example nobody can tell me how it works!?

For the variabel impedance trap thomas already gave me that kind of info i searched for. Thanks again  Smile

But these Basshnagers a myterius for me.
Is this traptype so private that nobody has to know the principal behind it?
When yes, i havt to live with it.

But where can i learn what you learn???
Any good books about acoustics?
I read the master handbook of acoustics 4 times the last 2 weeks, and also rod geravis book (not what i searched for).
next i want to read books about diffusion.


But i hope you can guide me to a answer for the basshnagertrap question.

cheers
constantin Smile

Ethan Winer

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Re: Ideas behind some unusal Basstrap types
« Reply #5 on: May 09, 2009, 03:32:48 pm »

franman wrote on Sat, 09 May 2009 01:16

this is how we make a living


There's only thing more exasperating than when someone asks me in a forum to describe in detail how my products are made and from what materials. And that is a thread that starts with a list of products they own from another treatment vendor, then asking me by name in their post for advice on what they should buy next from the competing vendor. Confused

Don't laugh. That happened just yesterday at a hi-fi forum. The guy even PM'd me to ask me to chime in on his thread. I told him No as nicely as possible! Shocked

That said, I'm more open than most people about proprietary info, mainly because I believe so strongly in sharing knowledge. I even made a video showing pretty much everything that goes into manufacturing RealTraps:

Made in Connecticut

--Ethan

Hank Alrich

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Re: Ideas behind some unusal Basstrap types
« Reply #6 on: May 18, 2009, 08:20:26 pm »

Ethan Winer wrote on Sat, 09 May 2009 12:32



That said, I'm more open than most people about proprietary info, mainly because I believe so strongly in sharing knowledge. I even made a video showing pretty much everything that goes into manufacturing RealTraps:

Made in Connecticut

--Ethan


You watch. People are going to be asking where can they get their own Connecticut!
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