# My bass trap design



## trifidmaster (Nov 18, 2006)

Hi, In my another thread:
http://www.hometheatershack.com/for...657-question-about-mixing-room-treatment.html
I am using my own made traps. I have designed and fabricated these panels many years back.

The frame is made from 1.8 cm thick MDF.
The inner cavity of the frame is 100 cm x 50 cm x 11 cm.
So, I can put into the frame 100 cm x 50 cm x 11 cm absorbing material.

All the sides are with holes, so that the actual surface of the trap is increased, by other words the sound waves can enter the trap from the sides as well.

The MDF elements are glued together, sand papered, and painted with powder paint.

For the panels I have used 10 cm thick 50-70-90 kg/m3 rock wool.
I could not find 10 cm think rock-wool, so I have used 5x2 cm, or 2x5 cm rock wool, to get the final 10 cm thickness. The extra 1 cm dept in the cavity is for the polyester batting.

The rock wool is covered with polyester batting, and finally it is pushed into the frame.
The batting is glued with spray glue on the rock -wool.










Currently I am waiting for a fabric. As soon as I have the fabric, I will post more info/photos.


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## trifidmaster (Nov 18, 2006)

Here is the finished frame:








See below the corner detail:


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## trifidmaster (Nov 18, 2006)

And here is the design. Enjoy.


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## maikol (Nov 7, 2008)

Very nice, Stefan!

Beautiful finish, also! :T


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## Prof. (Oct 20, 2006)

Very nicely done! :T
But I think it might have been a lot of work for little return..
The extra absorption would be minimal compared to the face area..


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## trifidmaster (Nov 18, 2006)

maikol, Prof.
Thanks!

Prof, if my calculation is correct, per panel with the holes I add approximately 29% extra surface.
Now, I have 14 panels. I believe that 29% extra surface per panel is remarkable, isn't it?

But please correct me if I am wrong.


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## maikol (Nov 7, 2008)

I've also read that you can add 30% of area with holes on the side as you did.


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## Prof. (Oct 20, 2006)

trifidmaster said:


> maikol, Prof.
> Thanks!
> 
> Prof, if my calculation is correct, per panel with the holes I add approximately 29% extra surface.
> ...


It will certainly increase the overall square area of the panel, but the effectiveness of extra area is debatable..
Considering that this is a first reflection point panel, which are generally fairly close to the speaker in comparison to the length of the room..Most of the reflected sound will hit the face of the panel..
Also, most panels only need to be 2' wide to be effective at reducing reflections..and of course you can never eliminate all reflections..

The only benefit that you might get is that there is less surface area on the timber sides of the panel, therefore a reduced area that sounds might be reflected from..
A bit like having timber framing instead of a solid timber construction..But again, very minimal effect..


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## trifidmaster (Nov 18, 2006)

Prof. said:


> It will certainly increase the overall square area of the panel, but the effectiveness of extra area is debatable..
> Considering that this is a first reflection point panel, which are generally fairly close to the speaker in comparison to the length of the room..Most of the reflected sound will hit the face of the panel..
> Also, most panels only need to be 2' wide to be effective at reducing reflections..and of course you can never eliminate all reflections..
> 
> ...


Prof, I see your point(s).

So, if the open side panels are having very little contribution, than there is no need to make open -sided panels. Huh, if I knew that, I would never spend so much time making them as they are. 

I am not a Prof, just a Doc (physicist).
So, being a scientist (natural science), I like to know if anybody has measured the "good" effect of open side panels? This is my scientific curiosity.
Do you have any reference/measurement data?


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## ToBeFrank (Feb 27, 2010)

trifidmaster said:


> Prof, I see your point(s).
> 
> So, if the open side panels are having very little contribution, than there is no need to make open -sided panels. Huh, if I knew that, I would never spend so much time making them as they are.
> 
> ...


I'd like to see measurements as well. My panels have fully open sides. That adds 4 square feet of exposed surface area to each of my 8 square foot panels. It looks like yours may be half that, which is still 25% more surface area than without the holes. I'm not convinced that when you add up all that extra surface area with all your panels that it's going to be a minimal effect.


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## Prof. (Oct 20, 2006)

trifidmaster said:


> Prof, I see your point(s).
> 
> So, if the open side panels are having very little contribution, than there is no need to make open -sided panels. Huh, if I knew that, I would never spend so much time making them as they are.
> 
> ...


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## eugovector (Sep 4, 2006)

Amateur opinion here: It seems that sound wave hitting at a trajectory from the sides are less likely to also hit your ears, as opposed to those hitting the face of the absorber.


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## glaufman (Nov 25, 2007)

Prof. said:


> Increasing the thickness of the panels is a far more effective way of obtaining more absorption, ..


Or by spacing them off the wall with an air gap behind...


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## Prof. (Oct 20, 2006)

glaufman said:


> Or by spacing them off the wall with an air gap behind...


:T


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