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PostPosted: Mon May 25, 2009 6:56 am 
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Location: France - Aix en provence
Hi everybody !


Today I began to build my first bass trap !!! :shot: :yahoo: lol (it's a projet I have for 1 year now, it was time to begin it !! )

I just bought enough to built only 2 panels, so as to validate the design. The frame is 2.5m high and 70 cm wide, made of strong fir tree slats (160mm wide, 28mm thick). It contains 150mm thick wool and will be covered with a clothe. I just finished one frame today and now I can see how (very) heavy and strong it is... and I wonder if something so heavy is really necessary ... so, what about making the frame with plywood, 15 or 20mm thick ? Is plywood good enough for that purpose ?

Thanks for your advices ! I'll post some pictures of the trap I'm building as soon as possible :)


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PostPosted: Mon May 25, 2009 8:07 am 
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welcome - I'd like to see the pics if you can post them :)


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PostPosted: Fri May 29, 2009 1:33 am 
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Location: Santiago, Chile
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According to some acoustics experts that design will have no effect and is a waste of material. For a bass trap to work it must be absorbative

Really? Wow! That's incredible! So you are saying that people who build panel traps, Helmholtz resonators, slot resonators, membrane traps, and suchlike are misguided, and have no idea what they are doing?

Did you ever manage to explain that to F. Alton Everest? I'm sure he would have been fascinated by your theory! Just as I'm sure that the real acoustic experts on this forum (who write books on the subject, and build world class studios every day) are also fascinated by it...

This truly is an outstanding revelation for the world of acoustics!

After all these, years, and all those Helmholtz resonators and panel traps that have been built all over the world, it really is fascinating to learn that none of them actually work...

:!:

- Stuart -

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PostPosted: Sat May 30, 2009 10:42 pm 
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Location: France - Aix en provence
Hi everybody !


here is some pictures of the first panel :

the wood frame:
Image

detail of the corner:
Image


Clothe on the back of the frame:
Image

the picture with wool indise is missing !

The finished panel:
Image

Image


Finally it is a strong and not so heavy panel, It will be a nice corner panel :). For the other panels I found better wood : $4.3 nice fir tree slat, 10 mm thick, 100mm wide and 2.4m high. It will be used for 100mm thick whool panel.


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PostPosted: Sun May 31, 2009 2:07 am 
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Looks very nice!

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PostPosted: Mon Jun 01, 2009 3:30 am 
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After testing my first panel I wonder that what I planned to do would make a very damped room for high frequencies (cloud panel is not showed here) :

Image






Would this this configuration be better ? :


Image
Image
Image

thanks your for your advice !


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PostPosted: Tue Jun 02, 2009 8:43 am 
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I think that new design will give you a bit better bass trapping.

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PostPosted: Wed Jun 03, 2009 5:16 am 
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oh, nice !! :D thanks


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PostPosted: Thu Jun 04, 2009 7:56 am 
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This weekend I was explaining to a friend my project of acoustic correction with hand made panels ... and he told me that Auralex kit where maybe as efficient, or maybe more than the panels I was doing, for the same price (around 600/ 700€) , which correspond to this :

http://www.auralex.com/sound_control_pr ... oject2.asp

or

http://www.auralex.com/sound_control_de ... xeplus.asp

What I'm wondering is, how a small LEND corner trap, which is only 2feet long (60cm) would be as efficient as a full panel of 2,5m high of 150mm of whool ?! Is it really efficient, especially if there are 8 placed in each corner wall/wall and corner wall/ceiling, combined with the the wedge panel?


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PostPosted: Thu Jun 04, 2009 3:10 pm 
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I think you mean "LENRD", not "LEND".

You might be interested in the data on this page, which compares the performance of LENRDS to another brand.

http://www.realtraps.com/data.htm

The LENRD line on the graph (purple line, bottom graph) is not very encouraging, since that is supposed to be a bass trap! There doesn't seem to much "trapping" of "bass" going on with those things: Below 200 Hz. (kind of where "bass" lives) the performance drops like a dead brick.

Quote:
What I'm wondering is, how a small LEND corner trap, which is only 2feet long (60cm) would be as efficient as a full panel of 2,5m high of 150mm of whool ?!

Answer: It cannot be. Not unless they figured a way to change the laws of physics! The graph speaks for itself.

Stick with what you are doing, I'd say.

- Stuart -

(PS. The graph for the wedge foam is not exactly exciting either... Yellow line, top graph)

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PostPosted: Fri Jun 05, 2009 4:10 am 
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Thanks SOundman !!

I just read a topic in the forum talking about the same thing :)

Okay, let's doing DIY panels !! :shot:


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PostPosted: Fri Jun 05, 2009 5:44 pm 
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Yeah, stick with DIY yer doin' a good job already. Standard (glass or rock) wool will absorb pretty good and it's waay cheaper. PLUS you can make it very, very custom to your likes :)

I'll link this threat in the sticky about absorbers (viewtopic.php?f=3&t=10304&start=0). thanx


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PostPosted: Sun Jun 07, 2009 6:49 am 
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New idea :

what about that :

Image

Image

three questions :

- Does it matter if the left Wall/ceiling panel is 40% shorter than it symetrical at right ?

- Does it matter if I place on the rear wall only acoustic foam and no bass trap ? Or do I need to bass trap a lot even in the rear ?

- Does it matter if there is no cloud panel ?

Thanks a lots for your help :)


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PostPosted: Sun Jun 07, 2009 3:35 pm 
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Quote:
- Does it matter if the left Wall/ceiling panel is 40% shorter than it symetrical at right ?
You should try to keep the room as symmetrical as you can at least as far back as the mix position. Behind that isn't so important.

Quote:
- Does it matter if I place on the rear wall only acoustic foam and no bass trap ? Or do I need to bass trap a lot even in the rear ?
It's a small room, so you should try to get as much bass trapping as you can into it.

Quote:
- Does it matter if there is no cloud panel ?

Yes! The ceiling is a first reflection point, and should have absorption on it to prevent reflections muddying the sound, creating comb filtering, etc.

- Stuart -

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PostPosted: Sun Jun 07, 2009 9:56 pm 
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Thanks Soundman

but what do you mean by : "You should try to keep the room as symmetrical as you can at least as far back as the mix position. Behind that isn't so important." ?

Does it mean that there should have wall/ceiling corner bass trap from the speaker to the mix position ?


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