DIY Ultratouch Cotton Bass Traps / Broadband Absorbers

[Implicit]

This thread details a DIY project I started in June of 2008 to build some broadband absorbers for my home studio using parts from Ikea for the frames and Ultratouch cotton for the absorption material. So far I've yet to finish the project due to other life priorities, but I am currently using 3 of the 5 absorbers in my studio now. As I get time and finish more work on the project I'll post the details here.

The design has gone through several iterations, so I thought I'd re-purpose this first post to be a table of contents to all of the relevant posts for each design iteration.

Design Iteration #1
Approach: Black Ikea IVAR sides and shelves, single brace, two batts of Ultratouch R21 in the shape of an 'S', and chicken wire on the inside.
Problems: Chicken wire installation is time intensive
Links: Part 1, Part 2


Design Iteration #2
Approach: Unfinished Ikea IVAR sides and shelves, six braces, two batts of Ultratouch R21 in the shape of an 'S'.
Problems: Ultratouch R21 bulges in the 'S' shape
Links: Part 1, Part 2, Part 3


Design Iteration #3
Approach: Unfinished Ikea IVAR sides and shelves, six braces, two batts of Ultratouch R21 flat in 3 layers.
Problems: The 3 layers of Ultratouch R21 bulges over time
Links: Part 1, Part 2


Design Iteration #4
Approach: Unfinished Ikea IVAR sides and shelves, six braces, two layers of Ultratouch R13 with one layer of Ultratouch R21 in the middle.
Problems: None so far...
Links: Part 1, Part 2


Parts Info
Ikea IVAR Bookshelf Info, Ikea Quality Issues
Ultratouch Cotton R-21, Ultratouch Cotton R-13
Guilford of Maine FR701 Samples #1, Guilford of Maine FR701 Samples #2


Links to other board members who built traps derived from my design:

• George Necola's design using 33" wide shelves instead of 17" and with chicken wire and rockwool instead of Ultratouch: Part 1 Part 2
• kywoman's design using 89" IVAR sides instead of the 70" ones: Part 1

Comments, suggestions, and criticisms welcome!

Last updated: 11/19/10

[Implicit]

After a few months of brushing up on the acoustics literature and getting ideas from other threads here on Gearslutz, I decided to take a stab at some DIY acoustic absorbers / bass traps for a new room I am setting up.

Objective: Free-standing absorber/traps with maximum surface area and thickness for very effective broadband absorption

Function: While Owens Corning 703/705 fiberglass and Rockwool / mineral wool seem to be the defacto for this type of thing, I opted to go with something more health conscious and environmentally responsible for the absorption material. With that in mind, I used Ultratouch insulation made from recycled cotton that is not bonded with Formaldehyde, can be handled with bare skin, and has superior acoustic performance for a comparable price.

Form: For the frames, I wanted to see what I could do using only common off-the-shelf parts to reduce the cost and time of the fabrication. I also wanted something free-standing so that I could easily reconfigure my room without having to redo wall-mounted absorption (been there, done that). To do this I used furniture parts from Ikea, chicken wire, and general hardware.

I want a polished look for final product and will most likely go with the standard Guilford of Maine FR701 fabric for the finish.

Cost: Total parts cost for each unit is around $84 (Ultratouch $36, Ikea parts $36, hardware $12) and will be right at $114/unit after I install the fabric. Construction time was about 3 hours. Not bad.

[Implicit]

Proposed studio layout. I plan to make 5 of these traps to implement a simple reflection free zone (RFZ) or I may make a few more and go for a full Attack Wall style setup.

[Implicit]

Ikea IVAR bookshelf parts: Side Unit, Shelf, Brace




Top mounting with corner brackets:




Bottom mounting with corner brackets:




Full assembly with cross brace in place:




Precision counts!




Chicken wire installed (stapled), ready for the Ultratouch to be fitted:

[Implicit]

Ultratouch R21 5.5"x16.5" Recycled Cotton Insulation bought from Green Depot. Each of these bags has five 94" batts:

[Implicit]

One finished unit ready to be covered in fabric. It has two batts of Ultratouch installed in it in a 'S' shape:

[Glenn Kuras]

pretty cool.. Kind of reminds me of our new table trap!!



Glenn

[Implicit]

Originally Posted by Glenn Kuras

pretty cool.. Kind of reminds me of our new table trap!!

Glenn

Hey Glenn,

Thanks for the link -- that is pretty sweet. Looks like a trap that could actually pass the "wife test" as they say!

[Implicit]

Glenn,

I just noticed you have FR 701 for sale on your website. Do you do samples as well?

Thanks.

[Implicit]

Picked up parts last night for 4 more traps:

[sethmeister]

Nicely done! Bet it will look fantastic with the cloth on.

[Implicit]

Originally Posted by sethmeister

Nicely done! Bet it will look fantastic with the cloth on.

I sure hope so, thanks!

I still need to decide on a fabric color

[Implicit]

I've received a few Private Messages asking about the frames, so I thought I'd add some additional info. The wood pieces and cross-brace I used to construct the trap frame came completely from parts for the Ikea IVAR shelving unit. The parts are intended to construct a shelving unit similar to the image below:



For the trap sides I used the following side units:

IKEA | Shelving units | IVAR system | IVAR | Side unit

The side units come in heights of 49", 70", and 89" and in lengths of 12" or 20". For my traps I used the 12" x 70" model.


For the top and bottom of the traps I used the following shelves:

IKEA | Shelving units | IVAR system | IVAR | Shelf

The shelves come in widths of 17" or 33" and lengths of 12" or 20" to match the appropriate side unit above. For my traps I went with the 17" x 12" because the Ultratouch batts come in either 16.5" or 24.5" widths and I knew the 16.5" batt width would fit great in between the 17" spaced side units.


The shelves sit on steel pegs that are inserted into predrilled holes in the side units, however, this can be insufficient fastening to hold the unit together. Typically you'd have more than two shelves, but since I only had one each at the top and bottom I needed to secure the shelves with corner braces. After installing the corner braces the units were rigid for the most part but still had a little sway, so I installed the suggested Ikea cross-brace which made the unit fully rigid.

IKEA | Shelving units | IVAR system | OBSERVATÖR | Cross-brace

The cross-brace comes in spans of 28" or 39" and I used the 28" for the traps.


Lastly, the IVAR comes in a painted black or untreated wood finish. For the initial trap I used the painted black because at the time I was unsure how and where I was going to attach the fabric and didn't want a bare wood finish in places, however, for the rest of the traps I am using the untreated wood parts. The untreated wood finish is slightly less expensive than the painted black finish which was another reason to go with untreated parts. For example, the first trap cost $14 for each side unit and $6 for each shelf, whereas the untreated wood parts for the remaining traps cost $12 for each side unit and $4 for each shelf.

I hope that clears up any ambiguity. If you have any questions please post them here or send me a PM.

[Ol' Betsey]

Now that's a nice looking trap.

Seriously.

Good work!

R.

[Implicit]

Originally Posted by Ol' Betsey

Now that's a nice looking trap.

Seriously.

Good work!

Thanks!

[Implicit]

Guilford of Maine FR701 fabric samples arrived today:




From left to right...
Top: 403 Vanilla Neutral, 404 Apricot Neutral, 401 Blue Neutral, 481 Pearl
Bottom: 538 Silver Papier, 380 Quartz, 400 Cherry Neutral, 394 Opal

[sethmeister]

Oooh! oooh! Get opal!

[Glenn Kuras]

Originally Posted by Implicit

Hey Glenn,

Thanks for the link -- that is pretty sweet. Looks like a trap that could actually pass the "wife test" as they say!

That seems to be the goal.

Glenn,

I just noticed you have FR 701 for sale on your website. Do you do samples as well?

Thanks.

Hey I just saw this post but I guess you got the samples direct from Guildford. Let me know if you need sample book of the FR701.

Glenn

[Implicit]

Originally Posted by sethmeister

Oooh! oooh! Get opal!

I think the Opal and Quartz are my current favorites...

[Implicit]

Originally Posted by Glenn Kuras

Hey I just saw this post but I guess you got the samples direct from Guildford. Let me know if you need sample book of the FR701.

Yea, I ordered a few samples from their website. Do your sample books have all the different colors/styles? Thanks!

[Glenn Kuras]

Originally Posted by Implicit

Yea, I ordered a few samples from their website. Do your sample books have all the different colors/styles? Thanks!

The one we send out is of all the FR 701 colors. I believe there is 48 colors to choose from. Boy thinking back now, only 3 years ago, we offered the Ford color selection, your choice of black or black for panel colors.

Glenn

[headrc]

Nice idea here ....and helps me with an approach I was thinking about. Can you tell me how much fabric you think you will need for one of these traps? I cannot find a source to help me figure amount in yards of fabric needed for panels etc. Thx, RH

[Implicit]

Originally Posted by headrc

Nice idea here ....and helps me with an approach I was thinking about. Can you tell me how much fabric you think you will need for one of these traps? I cannot find a source to help me figure amount in yards of fabric needed for panels etc. Thx, RH

The diameter of the finished trap is ~62" and the FR 701 comes in linear yards of 66" x 36", so I'll have around 4" excess to finish the vertical seem. The trap's height is around ~71" so it will probably take slightly more than 2 linear yards (66" x 72") to cover the trap from top to bottom since the top will be also covered with fabric. Hope that helps

[headrc]

Thx ...Actually that is about what I figured it would take to cover them. I hope you will post pictures once you have them done with the fabric on them. Of course I am sure we are also curious to know how well they work. Good thinking!

RH

[Implicit]

Originally Posted by headrc

I hope you will post pictures once you have them done with the fabric on them.

You bet

Originally Posted by headrc

Of course I am sure we are also curious to know how well they work. Good thinking!

Well here is the stated acoustic performance of a single sample of the Ultratouch R-19 and according to Bonded Logic's website, "Sound Absorption was tested in accordance with ASTM E90-02, ASTM C423 (Type A mounting per ASTM E 795)":

125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | NRC
0.97 | 1.37 | 1.23 | 1.05 | 1.0 | 1.01 | 1.15

I'm using the R-21 which is denser and has slightly better performance.

The measure of real-world performance though is the total surface area and thickness of the absorber. Each of these traps has 23.4 sq-ft of exposed absorption surface and a cross section of 15.5"x9.5". With that kind of depth/thickness combined with the large surface area should lead to excellent broadband absorption with substantial extended low frequency absorption.

I'd love to get one of the final traps into a lab to see what the total number of Sabins it measures, but I don't have the cash or time for that. Maybe I'll have to wait for another one of Ethan's shoot-outs... j/k

[Implicit]

Just a word of caution on the quality of these Ikea parts. I went to start building another unit and after attaching all of the corner brackets I noticed that the unit was not standing level. Upon further inspection I found that the bottom shelf was crooked and I removed it to investigate. Turns out, one of the metal rail inserts was not level because the wood was cut slightly at an angle as shown below:



After looking through the rest of my parts, I had 4 shelves like this and 4 good shelves. I must have picked out some from a bad batch because I only checked for warping and excessive knots when I was inspecting them at the store.

I know these things are $4 each, but it was a pain to drive back to Ikea just to swap out these shelves for proper ones. Anyway, caveat emptor!

[Glenn Kuras]

I know these things are $4 each, but it was a pain to drive back to Ikea just to swap out these shelves for proper ones. Anyway, caveat emptor!

Trust me with the price of gas these days it cost a lot more then $4

Glenn

[headrc]

Can you tell me what the dimensions "out of the box" of one of the Untratouch bats is? Was it tricky to install the way you did? Thx again, RH

[Implicit]

Originally Posted by Glenn Kuras

Trust me with the price of gas these days it cost a lot more then $4

You can say that again

[Implicit]

Originally Posted by headrc

Can you tell me what the dimensions "out of the box" of one of the Untratouch bats is?

Pretty much right at 94" x 16"

Originally Posted by headrc

Was it tricky to install the way you did?

Not really... you just stuff it in there in a zigzag shape -- takes about 5 min to get it all situated.