[Jazzman53]

Hi all,

I've decided to build some DIY bass traps and wall panels for my living room.  I ordered 18 2'x4' x 2 inch Rockwool 60 and some fabric, which should arrive in a few days.  In the meantime, I've been considering options for building the traps and panels.  The corner traps will use 4" of Rockwool 60 and 2" for the wall panels. One of the wall panels will be 42 x 56 inches and cover a window located directly behind my head when sitting on the sofa... I think this panel will make the most difference.
 
Most DIY wall panels enclose the acoustic material within a screwed-together wood or MDF frame, with fabric wrapped over the front and frame sides.  However; I prefer the aesthetics of an exposed wood frame, even though it takes more time and costs more for the higher finish quality.
 
For the corner traps; I will save a lot of money on wood by using a variation of this configuration; although I would wrap the fabric over the outside of the grill frame:
http://webblab.sk/home-studio/3-corner-bass-traps
 
For the wall traps; I plan to glue the frames together without screws, using finger joints, as shown in the first photo below. 

This morning I screwed together a small prototype frame from scrap wood and did some experimenting with tacking fabric to the inside of the frame using wood strips and brads. I found that it's no problem getting enough tension.  In fact; the fabric can be tensioned arbitrarily tight using this method.

The wood strips were 3/16 x 3/4 inches and cut to make a snug fit, and I cut up an old shirt for the fabric. It's fairly easy to pull the fabric between the strip and frame to achieve the desired tension. 

I first applied tension across the panel's midpoints in the vertical and horizontal directions and applied clamps, and then continued pull the fabric tight along the remaining edges while shooting in some 5/8" brads to nail down the strips.  The results were quite good.   
 
Lessons learned: 
- Sand a radius on wood strips and smooth over the sharp corners to prevent snagging the fabric.
- It's easier to remove clamps than brads or staples-- with enough clamps on hand, the tensioning can be fully completed and checked for tight corners and no wrinkles before committing to nailing down the strips.
 
The last photo shows a corner area, with the fabric pulled so taught that my tape measure sitting on it creates only a slight deflection.
 

[Freo-1]

Best of luck with your project.  Let us know how you go with this.

[dB Cooper]

Great to see some DIY going on in this area. $1K spent on room treatment will go 100x farther than the same amount spent on (for instance) boutique power cords. A glance through the photos shows many systems where big bucks were spent on equipment and tweaks while obvious room problems were ignored. As JLM says, "The elephant usually IS the room."

BTW I learned not long ago of the existence of something called 'acoustic wallpaper', a high-WAF tool to help your listening space. Check it out.

[Brettio]

Thank you for posting. I need to head down this path soon and your info is helpful.
Brett

[poseidonsvoice]

Nice work!

A full 80% of my 2ch audio investment is on the acoustics and room including a multisub (4 sub) setup. Once you’ve got that right you are golden.

Enjoy the journey and I really dig the exposed wood frame!

Best,
Anand.

[JLM]

+1, nice work!!  Hope it helps.  What problem were you trying to solve again?

[timind]

Wow, I really like that link for the corner bass traps. So simple to build, and looks as effective as any corner trap.

Good luck with the project. I'm sure the traps will help. Please keep us updated.

[Jazzman53]

+1, nice work!!  Hope it helps.  What problem were you trying to solve again?

Thanks. 

I was inspired to do this after hearing a really nice system setup in a dedicated sound room.  The first tune I heard there was Brian Bromberg playing Miles Davis' 'All Blues' on bass.  And I was absolutely floored by the tight, crisp quality of the bass notes. 

The owner explained that he had spent a full year dialing in the bass, which involved extensive room treatments, moving speakers around and testing with Room EQ Wizard.   

The system probably cost more than my house and included a pair of JL Fathom subs. I may not ever achieve that level of bass quality with my budget DIY hybrid ESLs and Ripole subs, but I want to improve it as much as I can, and I think room treatments will help. 

Starting with the basics-- corner bass traps and some panels to tame the first reflections, and especially reflections off a big window located right behind my head at my listening place on the sofa. 

[JLM]

REW is free (add $75 for the recommended mike), so analysis is cheap.

Geddes, Toole, LeJeune, and others really support multiple subs for taming bass issues (all residentially sized rooms have them).

Bromberg makes some jumping music. 

[Jazzman53]

Update Saturday June 29:
 
I have the big panel frame (which will cover the window behind the sofa) and three smaller 24x48 wall panel frames essentially completed--- just applied the first coat of satin polyurethane this morning, which will be sanded and final coated later today.   The big frame will have a Carverfest 2015 banner covering the acoustic batting. The smaller frames will have a camel colored fabric over the batting.  Frames will be exposed.






 
 

[Jazzman53]

Update Tuesday July 2:

I've completed three wall panels and a pedestal panel, all with 2" thick, 6lb density Rockwool and exposed brown oak frames.  One of them is a 56" x 42" panel placed over a window behind the sofa and covered with a Carverfest banner. 

Tomorrow I will start the floor-to-ceiling corner bass traps.  Below are more build pics:

[poseidonsvoice]

Jazzman,

This is very, very nice work. Had I paid closer attention I would have advised you to go for 4 inches minimum thickness for the Rockwool as it provides 1 octave more deeper extension (~250Hz versus 500Hz) for even better decay times and more balance from a spectral standpoint.

The tradeoff is cosmetic of course but if your room is big enough, then even that can be taken care of from a visual standpoint. The one particular treatment I would have made 4-6 inches thick would be the “Carver” one since it is clearly on your backwall and would take care of the rather annoying backwall midbass and bass reflections present in most audio rooms where the MLP is less than 10 feet from the backwall.

In fact on my backwall which is about 10-12 feet away I built a hybrid unit. It is about 4-5 inches thick of Owens Corning 703 with a built in airgap coupled with an aperiodic Stepfractal diffuser in front of it (similar to RPG Acoustics). The front of the absorber/rear of the diffuser is lined with FSK to minimize over absorption so as to prevent overabsorption and hence dulling of the high end. As expected this entire contraption is about 8 inches thick overall. Acoustically this  takes care of the low frequency bass slap off the rear wall (500 Hz down to 100Hz) and for frequencies >500Hz to about 4khz (the midrange) it provides the diffusion many desire. A diffuser on the backwall as I have done would only be recommended for those rooms that have the MLP at least 8 feet and preferably 10 feet away to minimize comb filtering. If it’s less than 8 feet, I would recommend absorption and the thicker, the better.

In any case, I applaud you for your work and efforts! It will pay off handsomely so you can spend more money on music and less on the gear since for most audiophiles their rate limiting step is actually the room!

Best,
Anand.

[Jazzman53]

Thanks Anand,

After reading your post, I've decided to insert another two-inches of 6 lb Rockwool in the window cavity behind the big panel, which is easy to do, and would make 4 inches total in the center portion of that panel.   

I will be making floor-to-ceiling super chunk type corner traps next.   

[poseidonsvoice]

Thanks Anand,

After reading your post, I've decided to insert another two-inches of 6 lb Rockwool in the window cavity behind the big panel, which is easy to do, and would make 4 inches total in the center portion of that panel.   

I will be making floor-to-ceiling super chunk type corner traps next.   

Jazzman53,

I am glad it is easy to do, sorry if I came on too strong! But acoustically it makes sense for many setups that just don’t have enough absorption in the 1st place.

Best,
Anand.

[JLM]

Are you listening/measuring as you go along?  Hard to tell how much of the walls will be treated, but like most anything, treatment can be overdone, and humans being so adaptable acclimate quickly. 

[poseidonsvoice]

Jazzman53,

Just as an aside, for nearly all my treatments I used OC703/705 lined with FRK material to minimize mid and high frequency absorption so as to not have too “dead” of a room. One can do real measurements with REW to verify this. It’s not something you will see on a frequency response curve. You will see it in the “Decay” curves. The amount of decay you want to achieve in the mid and high frequencies is strongly dependent on the application. Studio’s want 0.1 to 0.3 seconds, home theatres 0.3-0.4s and 2 ch listening rooms sound good at 0.3-0.5s. Obviously personal preferences vary but greater than 0.5 seconds means you need more absorption and/or diffusion in that frequency area. Note you can have pretty good decay times and quite a bit of diffusion in the room. And room size makes a difference too. The area to concentrate heavily on is the mid frequency band, i.e. 300Hz to about 4 khz. Getting low decay times (~0.4s or so) in the bass (<100Hz) can be difficult and expensive. But it is terribly important to address as well. Wonder why OB speakers have less 'room boom'? It's because they have lower decay times. I've measured it, numerous times. The lower decay time is primarily because of less output in a figure of 8 pattern; it is an example of controlling directivity, and in this example, I am talking about the midbass/bass area. Of course OB's have other challenges that need to be overcome.

https://www.atsacoustics.com/owens-corning-703frk.html?d=GPGEN01&kw=1004frk-703FRK-2&gclid=EAIaIQobChMIqp276deY4wIVB1gNCh2anwWwEAQYAiABEgIsDfD_BwE

I didn’t use ATS but just posted the link to illustrate an example. I am sure there is an OC705FRK as well.

I doubt you will "overtreat" your room. The real concern is not having enough absorption that extends into the midbass/upper bass which makes the room sound spectrally dissimilar. It will sound like you over absorbed the high frequencies. Hence the recommendation for 4 inches or thicker in select areas of the room. 2 inch thick absorption panels are really good for treating slap echos in high ceilings, cathedrals, schools and places of worship, not really most 2 ch rooms that have 'small room' acoustics issues. The other thing to make note of is the polar response of your loudspeakers. But for starters, all 2ch listening rooms in my opinion need bass traps in the corners and treatment of the back wall (particularly if it is close). A back wall that is 20+ feet away may not count, and the room at that point is approaching a ball room. For most but not all speakers, the sidewall 1st reflection points are quite important to treat and what treatment you place there has greatly to do with the intended application of the room/system, placement of your main 2ch loudspeaker relative to the side walls, and polar response of said speaker. Thereafter, the ceiling, front wall and in some cases, the floor is quite important as well.

Oh...please don’t use foam. That’s a great example of over absorption of the high end and under absorption of the low end hence the skewed decay times and the opinion that you have “over treatment.” Stick with rockwool, fiberglass like OC 703/705, etc...much more balanced absorption versus foam.

See here:
http://www.acousticfrontiers.com/wp-content/uploads/2011/10/acoustic_measurement_standards.pdf

And here:
http://arqen.com/acoustics-101/room-setup-speaker-placement/

Best,
Anand.

[Jazzman53]

Are you listening/measuring as you go along?  Hard to tell how much of the walls will be treated, but like most anything, treatment can be overdone, and humans being so adaptable acclimate quickly.

I just bought a mic and downloaded REW but I haven't connected it up or learned how to use it yet.

[Mike-48]

In fact on my backwall which is about 10-12 feet away I built a hybrid unit. It is about 4-5 inches thick of Owens Corning 703 with a built in airgap coupled with an aperiodic Stepfractal diffuser in front of it (similar to RPG Acoustics). The front of the absorber/rear of the diffuser is lined with FSK to minimize over absorption ...

Anand,

FSK?  I can't be the only one who doesn't know the abbreviation.  Or am I?

Mike

[poseidonsvoice]

Anand,

FSK?  I can't be the only one who doesn't know the abbreviation.  Or am I?

Mike

FRK Paper is a foil reinforced kraft paper that is used as a vapor barrier for fiberglass and mineral wool insulation rigid board products.  FRK is also known as FSK (Foil, Skrim, Kraft).

Some acoustical engineers have done testing that show that using FRK faced fiberglass or mineral wool rigid board with the FRK side facing the room will allow the panel to absorb lower frequencies while reflecting some of the mid to high frequencies to help "liven" up a room and prevent a "dead" sound.

Best,
Anand.

[mcgsxr]

Great work!

I used a Roxul product in my own, as that specific Owens product is hard to source in Canada.

I went 3 inches of material in a 4 inch frame hung 1 inch off the wall for my first reflection point panels.

Corner bass trap was the same, but the cavity behind the trap was filled with more Roxul product.

It's well worth doing, and if you measure I'd be interested to see how what you hear matches what you measure - I never measured, and am happy with the results in my space. 

My cats are happily climbing them though, so I may have to recover in the future.  I used cheap grill cloth material from the local fabric store.  They had a beige cloth that was close to wall color for me, and on other traps I used some cheap leopard print since I knew the cats would go at it.