Portable DIY absorption panel build...

Many have been mentioning the need for mobile absorption panels. I just built four of these and love 'em. Since my speakers often change so does optimum placement...which means first reflection point changes...which means where the panel is located needs to change. Portable panels make that a non issue. It also makes them easy to remove from the room in the event the SO is having a hard time accepting your dedication to achieving higher levels of fidelity and the moments of bliss afforded you by the panels' contribution to your bitchin acoustic treatment scenario.

Enjoy (click on images to enlarge)...

1x2 pine, muslin cloth backing, speaker grill cloth outer covering (burlap or muslin works great, as well), 2" OC703 (or 3" Roxul SafeNSound). Easy.

Screw frame together....



Add gussets to corners (I cut mine from 1/4" ply) or install metal corner brackets...



Cover with muslin cloth, staple and trim then set aside....





Lay panel covering material out and place OC703 on top and trim leaving about 6" around edges...



Set covered frame over 703 so the muslin cloth is making contact with the OC703. This non-nested method exposes all surfaces of the 703 and ensures absorption on the sides of the panel. If you use SafeNSound you'll have to nest it inside the frame (it's not as rigid and won't hold its form as good as OC703 so it needs the support of the frame)....



Now bring the excess outer covering up to the back of frame and start stapling it down. I like to start with the sides and staple from the middle out while pulling cloth to keep in taut. ..



Finished panel (which at this stage could be hung on wall, ceiling, etc.). I should note here the bumpy, irregular edges are not inherent to OC703. It looks like that because those panels I used have had the edges beat up from getting moved around a lot over the course of the last few years....



The stands are simple 1x2 screwed to the panel frame. You can use inexpensive pine or decorative hardwood and make them any length you wish. Bringing them up the full height of the panel would look nice...sort of a quasi-frame. The height of the panel at its horizontal center is set so that it's the same as my ears when in a seated listening position. The feet are cut from plywood and you can shape them any way you like. Decorative metal shelf brackets could be used as well.

Also, if you need to store the panels away when not listening you could "T" a piece of 1x2 to the bottom of the vertical "leg" and not completely tighten it down...just snug it...so that the foot can be swiveled (kind of like DCM did on the Time Frames). With that you can stack the panels one on top of another in a compact fashion without the feet interfering or protruding making them easy to store away when not in use...and effectively rendering your excuses for not being able to use acoustic treatments in your space because of WAF, existing decor, etc. to the realm of the irrelevant. :yes:







Done....



Here's a nested panel using Roxul SafeNSound. That's screen door screen on the back. The front will get trimmed out with quarter round to cover the edge of the covering material and staples. These are to be located at the rear wall so I'm not as concerned about the sides of the panels being absorptive. Stands for these could be constructed using a method like or similar to the one above.





Here's info on how to find the best places in the room to locate the panels....

http://audiokarma.org/forums/showthread.php?t=446798

- Michael



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Nice job! I've been wanting to build some panels. My local HD and Lowes don't carry the 703. Where are you finding it?

Mark

Amazing Michael !!! , I sent you my sketch would you do one of these also behind each one of my speakers? And also the first reflection and behind my chair ? Thanks for posting this . Now I can move them around to experiment .

The look way cool on the legs

opa1 said:

Nice job! I've been wanting to build some panels. My local HD and Lowes don't carry the 703. Where are you finding it?

Mark

Click to expand...

Thanks! OC703 can be sourced from industrial insulation supply houses...where heat/ac repair and installation guys go to get their insulation. Or you can mail order it.

Thanks. I didn't think of looking there. Did find it online.

Mark

Michael,

It seems like you have the 703 sitting on top of the 1X2 and held on by the black material. Is that correct? I was thinking you would make the frame large enough so that the 703 fit inside of it. Which way is correct?

f

crwilli said:

Michael,

It seems like you have the 703 sitting on top of the 1X2 and held on by the black material. Is that correct? I was thinking you would make the frame large enough so that the 703 fit inside of it. Which way is correct?

Click to expand...

You are correct...the 703 is sitting outside of the wood frame which makes it a non-nested design. The last few pictures shows a panel with absorption medium (Roxul SafeNSound in this case) sitting inside the frame which is a nested design. I prefer the non-nested design for sidewalls since it makes half the area of the side of the panel absorptive as well. With a nested design the entire side of the panel is reflective. Since the side of the panel will have sonic content dispersed into it from the speakers (at an angle) having absorptive surface area there means less content is reflected back into the room (as would be the case if the entire side of the panel was a wood frame). For front and rear walls this is not as critical since sonic content from the speakers is dispersed more directly into the face of the panel.

Thanks Michael. I like it in its simplicity. What frequency range do these best absorb? And can they be enhanced by doubling the thickeness?

I am sorry for my laziness by asking questions that no doubt, I could answer if I did more research.

Craig

crwilli said:

Thanks Michael. I like it in its simplicity. What frequency range do this best absorb? And can they be enhanced by doubling the thickeness?

I am sorry for my laziness by asking questions that no doubt, I could answer if I did more research.

Craig

Click to expand...

No problem...I'm happy to answer them. These are pretty much broadband absorbers as you will get 100% absorption of content from 250 Hz and up and 70% absorption at 125 Hz if you space them 16" from the wall. Place them on the wall and absorption is 85% at 250 Hz but at 125 Hz performance takes a nose dive as absorption drops to 17%...so there is a big gain in mid bass absorption if you can get them spaced away from the wall and I strongly recommend you do as muddy, incoherent mid bass has a way of making everything sound worse. Doubling the thickness of 703 to 4" will bring on-wall performance up to similar values as 2" spaced away from wall. Interestingly, 4" spaced away from wall is not any better than 2" spaced away from wall.

Looks lovely Michael!

tomlinmgt said:

No problem...I'm happy to answer them. These are pretty much broadband absorbers as you will get 100% absorption of content from 250 Hz and up and 70% absorption at 125 Hz if you space them 16" from the wall. Place them on the wall and absorption is 85% at 250 Hz but at 125 Hz performance takes a nose dive as absorption drops to 17%...so there is a big gain in mid bass absorption if you can get them spaced away from the wall and I strongly recommend you do as muddy, incoherent mid bass has a way of making everything sound worse. Doubling the thickness of 703 to 4" will bring on-wall performance up to similar values as 2" spaced away from wall. Interestingly, 4" spaced away from wall is not any better than 2" spaced away from wall.

Click to expand...

Thank you! So a quick follow up. If I were to cut an additional piece of 703 to fit inside the frame, I could improve the absorption closer to the wall?

Seems my room, when finished, will have resonances at about 75 Hz (height) and 78 Hz (width) and the multiples of them. Looking to be the worst at about 223 - 226 when they combine with a length resonance. Your panels will likely come in very handy and give me yet another thing to play with in my journey. Only this tweak\improvement is cheap!

That's superb work. Gives me ideas.

I have been thinking of building very similar panels to eliminate "first reflections". One question , my speakers are dq10's they are somewhat of a dipole speaker. I would not want to put a panel behind these speakers correct?

dgiff said:

I have been thinking of building very similar panels to eliminate "first reflections". One question , my speakers are dq10's they are somewhat of a dipole speaker. I would not want to put a panel behind these speakers correct?

Click to expand...

Correct, one typically doesn't want to kill the rear wave coming from a dipole which is what will happen if you place absorption behind it. I believe the only exception to this rule is 1) individual taste (some don't like the sonic contribution made by a reflected rear wave) and 2) when a dipole design has to be placed close to the boundary layer behind it, say within a few feet, in which case resonances can develop and would need to be eliminated with absorption.

It is generally agreed upon that diffusion is the ideal acoustic treatment behind a dipole.

- Michael

I'm bookmarking this thread - been meaning to do something similar, but the pictures and explanations here are the clearest I've seen. Thanks.

Can someone think of an IKEA stuff that can be a frame substitute?

davidro said:

Can someone think of an IKEA stuff that can be a frame substitute?

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Do you have (very) basic woodworking skills and basic hand tools? That's really all it takes, David. I don't think this could be any simpler. You could build these on the living room floor. Literally. The feet might be a bit tricky if one is really DIY challenged, but decorative shelf brackets could be used as a substitute.

The thing is that I live in a smallish unit with no tools Michael. I was browsing at IKEAs a bit and thought I saw things I could use for the frames.

Ahh...wasn't aware of your limitations. Maybe ask an employee at a hardware store if he wants to make a little money on the side and hire him to build them.