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DIY acoustic absorption panels begins

davidro

davidro

Lunatic Member
I've been obtaining advice from Michael (aka tomlinmgt) re acoustic absorption panels. Being in Down Under my options are limited and I finally settled on 75mm Tontine Acoustisorb3 (240x120cm, 3 sheets/blankets). It's performance is as below:

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Getting them wasn't easy. The cheapest dealer wouldn't open during weekends and I don't have time weekdays. And the delivery costs was like A$88, obviously tailored for commercial buyers. I've finally located a dealer who would pass them to me at his home on Saturday. He also agreed to cut them into 120x60cm size for a nominal fee. I live in a small unit and have no tools/expertise.

This is how my listening room (aka living room) looks:

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I'd like to have some portable panels behind the speakers and in front of the window walls. That would do some good trick. As for side walls and back walls, I'll just cover the panels with acoustic cloth and hang them onto the walls. Michael suggested having some space between the panels and walls would be more effective but I don't have that much of space luxury.

I'm hoping they're stiff enough so that I don't have to frame them or something.

As for portable panels, instead of going DIY frames, I was thinking of getting some cheap easels. What do you think? On that auction site I see 2 offerings (#291107373889 & #251442014717). I like the cheaper one.

Suggestions are welcome :)
 
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Or perhaps I can even hang them on the curtain hanger using some thread? That sounds like an idea too.
 
I like the hanging panels idea. The easel idea is good, as well. Before I built stands for my portable panels I had them hanging from the ceiling with thin guage utility wire.
 
davidro said:
Or perhaps I can even hang them on the curtain hanger using some thread? That sounds like an idea too.
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Michael (Tomlinmgt) is the room treatment guru and professional baffles and sound panelling are clearly the best way to go. However, these professional and sound specific DYI treatments can be complimented by a trip to Spotlight (An Australian retailer).

After reading quite a few posts in 'Listening Spaces' I decided to have a crack at a 'decorators' approach to sound baffling rather than purely 'technical' approach to see if I could make a difference to sonic characteristics of a space. Over a period of time I gradually replaced art work with rugs and fabric. After writing a thread and getting some seriously great advice and direction to tons of reading material I took down everything I had added specifically to the space as a 'treatment' to see if I could hear a difference, to my surprise there was a noticeable difference.

Have a scroll through these photos (14 in total) to see what I did with limited knowledge and a little intuition + plus there is a blurb under each photo:

http://s1027.photobucket.com/user/koorabri2/media/IMGP1347_zps288b1350.jpg.html?sort=2&o=12

I am about to move house so this has given me the opportunity to rethink what I can in the next place. Firstly, I am going to construct some DYI sound baffles that Michael and others have posted. But the one thing I have learnt is that hanging rugs straight on the wall is not as effective as hanging them from a curtain rod. Using a rod means the rug is a couple inches away from the wall allowing the sound to get behind the rug which will improve the dampening characteristics of this approach. This is not a solution but rather intended to be complimentary to the baffles I also intend to hang.

Finally, the fabric frames I DYIed are not a perfect solution but used in conjunction with professional baffles and rugs do help the room acoustics and help make the room not look like a studio or your an audiogeek (nothing wrong with that if your happy to be out and proud). I have been gobbsmacked at the extra attention from the ladies at what a little extra effort gets you with a few room aesthetics.

Hope this helps you on your journey.
 
Thanks for the suggestions Brin. Someone else also suggested stuffing the room with lots of objects would naturally do a bit of acoustic absorption work. As for me, I like to keep my room as empty as possible, and placing a few DIY panels with blank acoustic cloth has more appeal.

As for having a gap between the wall and the panels, Michael also made the same comment previously. I'm thinking of creating a bit of gap, say about 5cm, between them by placing some planks or something.

I don't even know what colour these Acoustisorb come in, depending on which I should choose the acoustic cloth. I was thinking of some groovy guitar amp grille patterns but that might make me bored easily. Perhaps I should just stick with plain white or cream colour. Cream would be nice as it would match with my wall colour.
 
And I'm thinking of attaching the Acoustisorb to the mesh using some thread. Perhaps I can also attach some buttons in doing this so as to make the panels look like the buttoned sofa surface:

bladon_button_sofa_cleves_72_0-e1291892383850.jpg
 
Ok got them raw. Can't wait to try them. They're pretty stiff, so I place them against the window wall. A couple on the floor in front of the speakers. Some more behind my listening position. And the difference? WOW. It sure is day and night difference and not in an audiophile sort of way. SUBSTANTIAL difference it is. This truly is worth the investment. The tuttis are so resolving and clear.

Now that I'm convinced how do I wrap them up most effectively? I'm thinking of wrapping them in some anti bird netting and then wrapping them again with acoustically transparent cloth. That way I will be able to hang them without causing too much grief. They're pretty stiff so I might not bother with frame which may cause side-way acoustic blocks anyway.
 
davidro said:
WOW. It sure is day and night difference and not in an audiophile sort of way. SUBSTANTIAL difference it is. This truly is worth the investment. The tuttis are so resolving and clear.
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:yes:

Put up a pic of one of them Acoustisorb panels, Dave. Lemme' see what you're working with.
 
Thanks, Guy. I was hoping to see a pic of an entire panel, preferably leaning up against something, so I can get an idea of how rigid it is. When David forwarded the Acoustisorb info to me several weeks ago I got the impression its rigidity falls somewhere between OC703 and SafeNSound.
 
Here ya go Michael, what do you think?

CIMG5696_zpsfa6081f6.jpg


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Now I feel it's slightly too dead. But I can adjust that as I've literally plastered the back wall with the panels as you can see in the photo. And the sidewalls need some attention too. I feel like adding some on the ceiling too. It's revealing how on a high volume the music does not lose posture.

Don't worry about headroom, wattage etc. You need room treatment first!
 
Ok, that Acoustisorb is practically the same as SafeNSound but black instead of **** green. You're going to have to frame them panels or they'll be an eyesore. And since the Acoustisorb doesn't hold its shape well you'll have to make all panels a nested design (absorption medium inside the frame). No sweat...they'll still work just dandy.

Look at what I did here....


This is the back of the panel and I've covered it with mesh screen (the stuff you use to screen windows and doors ) and stapled it down (gonna need a good staple gun if you don't already have one) on the back to contain the SafeNSound.


ujyda3ed.jpg



This is the front and I've simply stapled down my fabric facing and trimmed the excess around the edges......


2uqu5u5e.jpg



...and then used quarter-round trim to cover up the staples and edges of the fabric.


yzy4ysy5.jpg



Yes...the way you have the panels set up in the picture will certainly illustrate that this absorption panel business is definitely not snake oil, but there does have to be some method behind the madness. My placement suggestion is pretty consistent for a fundamental treatment scenario....

- a panel at side wall first reflection
- two to three panels on front and rear walls
- a panel at first reflection on ceiling for each channel
- thick rug on the floor if not carpeted

So for you, David, I suggest...

- two panels at the front (glass) wall behind the speakers (hanging from the drape rod so you can slide them from side to side to fine tune)
- two for side walls so that's one at each side wall first reflection point
- three on the rear wall with one directly behind the listening position and the other two flanking the center one with about a 30-45cm gap between the panels
- two on the ceiling (if you feel like giving that a go)
- and a rug on the floor (you don't have to have absorption on the floor and ceiling, but you have to have absorption on at least one of those two surfaces).

You can hang the panels on the ceiling such as I've done here using hooks and plant hangers (I know, my unfinished garage ceiling looks like ****....I'll paint it this summer) like this....

avere4ez.jpg



And do try to get some airspace between the panels and the wall, if even just a few inches.
 
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Thanks Michael. Really appreciate it.

As for the gap between the panels and walls/ceiling I may not have the luxury of the space as my room's pretty small already. I feel it should be good enough for me really though, having tested the raw panels.
 
Keep in mind you are best to not have all the panels exhibit exactly the same absorbing spectrum. Spacing a few, in whatever manner, can be more effective than all at the same distance.

So with room space being at a premium, you can pick a few where there is ability to get a couple inches and space them off. That gets you different characteristics and keeps from over doing it at some freqs and not doing much at other points. They don't have to be out a foot or anything, just a couple inches.

EV3
 
The reasoning behind having the panels off the wall a bit (as I've come to understand it) is this....if you can trap the traveling sound wave while it's traveling at a high velocity you can achieve more effective absorption. Effective absorption is all about removing energy from the traveling sound wave and the faster the sound wave is moving when it meets the absorption medium the more resistance to flow (friction) it will encounter which results in a greater loss of energy than if the resistance is presented on the boundary layer surface. You see, the point at which the sound wave strikes the boundary layer surface and returns into the room is a low (zero) velocity episode so absorption at this point is less than ideal because the sound wave has already lost a good bit of its energy to the resistance of the boundary layer. So when the absorption medium is actually on the wall the loss of energy is a single episode of resistance/friction....when off the wall it's three episodes of resistance/friction (once when it encounters the panel, once when it meets the boundary layer, and once again when it's reflected off the wall and into the panel a second time). That's why the only design I like for on-wall mounting of the frame is a non-nested design (like I have in my DIY absorption panel build) because it has airspace inside the frame and between the absorption medium and boundary layer.
 
When making one of these nested panels, would it be more beneficial to make them of 2 or more thinner layers with deadspace between each?
 
GuyK said:
When making one of these nested panels, would it be more beneficial to make them of 2 or more thinner layers with deadspace between each?
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You mean to make the total panel more effectively absorb lower frequencies than if the layers of absorption medium were just stacked together? I've never seen that method utilized or recommended by the acoustics "gurus" over at GearSlutz. They generally recommend more thickness for absorbing lower frequencies. The bass traps often use some sort of membrane (similar to craft paper or thin poster board) to help them achieve absorption is the first few octaves.
 
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