How I built my bass traps (superchunk method)

John Shryock · Post by **John Shryock** » Sat Oct 14, 2006 4:27 pm

Here's the way I did the studiotips superchunk bass trap. I'm sure that this design has been posted before, but I just wanted to give my input on it, and share the pictures on how I did it. I did the bass traps about a year ago and have just gotten around to posting these pics!

Hope it's useful to someone..

Pic 1

First I bought a bunch of fiberglass insulation. I bought johns manville, and whatever the best was recommended around these forums. It was about $40 per bag.

Pic 2

Then, I cut the pieces in half, and then into triangles. I cut them using a drywall saw (if i remember correctly). I also found that you can cut multiple pieces at once - I was able to successfully cut three or four pieces at one time. That saved time.

Pic 3

Next, I stacked these triangles up in the corner. They were kind of toppling over, so...

Pic 4, 5

I drilled these fish-eye hooks into the drywall and used some wire to secure them from falling over. The wire goes overtop of the stack, then down the face of the stack, then up and behind it, to meet the hooks again. Even though it's not mega-powerful, it was enough to keep them from falling over.

(post continues)

John Shryock · Post by **John Shryock** » Sat Oct 14, 2006 4:35 pm

Pic 6, 7

I stacked the triangle pieces to the ceiling, essentially in two groupings, each secured with a wire tied around the stack.

I also added two small poles. I added the poles by using the silver things in picture 7. Their name escapes me (it's very late at night), but they are basically metal studding/framing pieces which I found in the lumber section.

Pic 8

Then I added clear painter's drop cloth around the insulation, to prevent fibers from leaking in the air. I just kind of stuffed the dropcloth at the very top and underneath the bottom of the stack.

Pic 9

The final step was to get some fabric from a fabric store and then use a staple gun to staple the fabric to the wood posts I put up. This was excellent and they look great. I made sure to pull the fabric taut so that it would look nice and flat. Very effective: just long fabric and a staple gun.

This first pic is of the one next to my mixing desk.

Pic 10

Here is another bass trap behind my drumset (not me drumming though.. I wish I could play like he did!.

)

All and all they are awesome looking and very easy to build. However, it did take some time to figure out how I would be building them. Hopefully this will save you some time.

I didn't do any intensive before and after tests, but I did play a test sine wave down to 20 Hz and it was pretty even throughout. I believe that these bass traps are effective.

Anyways, this post was done late at night, so it's probably not the most well-written. Maybe I'll revise it later - hope it helps somebody out!!

BTW - there was too much foam on the walls next to my mixing desk, but I am redesigning the studio - and definitely keeping these bass traps!

johnz · Post by **johnz** » Sat Oct 14, 2006 11:45 pm

cool. i think your bass trap might be a lot more effective if you remove the plastic sheet in between your insulation and fabric.

John Shryock · Post by **John Shryock** » Sun Oct 15, 2006 5:49 am

my thoughts on that, from my limited knowledge:

having the plastic doesn't affect the functionality of the bass trap, at least for the actual bass frequencies. the 1 or 2 millimeters of plastic sheet has almost no effect on low frequency content. imagine standing behind a plastic painter's dropcloth like the ones i used - it offers almost no sound barrier whatsoever. however, the plastic might function similarly to RFK fiberglass, giving a slight reflection in high frequencies.

having the plastic does keep the glass fibers in better than not having it, although that may not be entirely necessary either.

now, i may be entirely incorrect - in this case, would someone please put me on the right track?

thanks,

John

knightfly · Post by **knightfly** » Sun Oct 15, 2006 1:39 pm

NO, you're right; this can also be done with thinner, wall or ceiling absorbers to keep the room a little "brighter"... Steve

BTW, moved this to Acoustics and added it to DIY treatments "sticky".

Post by **sharward** » Sun Oct 15, 2006 4:02 pm

Excellent how-to with photos.

Thanks for sharing!!

--Keith

len-morgan · Post by **len-morgan** » Sun Oct 15, 2006 9:18 pm

John,

You didn't mention flame-proofing the fabric. Did you do that or did you buy already flame-proof stuff?

When you mount fabric vertically like this, it's ability to burn at an alarming rate is increased. You can get spray-on flame retardant (see References thread at the top of the forums).

If you started with flame-proof fabric, an extra 2 points!

len

Tonio · Post by **Tonio** » Mon Oct 16, 2006 1:28 pm

Hey Nice work there John!!

BTW, 4mil palstic srim seems the norm for bringing back the high end. How would 6 mil work out, anyone?

T

knightfly · Post by **knightfly** » Mon Oct 16, 2006 4:51 pm

Not familiar with any semi-serious documented test of the diff; although this would be much easier to do than MOST acoustic treatments - just put up all the rockwool you're gonna use, test without plastic, temporarily tack really thin (like painter's drop cloth) plastic up, test exactly the same way/place, tear that down, put up 1 mil, repeat, etc... Steve

AVare · Post by **AVare** » Mon Oct 16, 2006 11:35 pm

Great stuff. great pictures!

Thanks for sharing
Andre

John Shryock · Post by **John Shryock** » Tue Oct 17, 2006 12:49 pm

I did not use flame retardant fabric, nor did I spray the flame retardant spray on. -2 points! I will get some on it soon!

this can also be done with thinner, wall or ceiling absorbers to keep the room a little "brighter"

Do people think the superchunk method is a little too space consuming? Are there increased bass-trapping gains due to the bulkiness?

I am building some more bass traps soon, and was planning on using the exact same strategy, unless someone chimes in to say otherwise. I remember this superchunk strategy tested very well while I was researching bass trap designs.

Thank you,

John

mike0370 · Post by **mike0370** » Sat Oct 21, 2006 6:57 am

knightfly wrote:Not familiar with any semi-serious documented test of the diff; although this would be much easier to do than MOST acoustic treatments - just put up all the rockwool you're gonna use, test without plastic, temporarily tack really thin (like painter's drop cloth) plastic up, test exactly the same way/place, tear that down, put up 1 mil, repeat, etc... Steve

I am familiar... get this info out there gentlemen...maybe sticky? Bob Golds? ........ the BBC comes to our aid again on this one

http://www.bbc.co.uk/rd/pubs/reports/1992-11.pdf

Figure 9 on page 4 of this report shows test graph with plastic and without on a rockwool absorber. The absorption appears to be the same below about 500hz.... so it would be a true broadband bass absorber by the fact that its absorbing all bands (broadband)considered to be "bass" but NOT high frequencies... the thicker the trap the lower the included frequencies of absorption. thank you

Post by **John Sayers** » Sat Oct 21, 2006 8:46 am

That BBC article doesn't even mention plastic. It's refering to something entirely different.

cheers
john

mike0370 · Post by **mike0370** » Sun Oct 22, 2006 1:59 am

John Sayers wrote:That BBC article doesn't even mention plastic. It's refering to something entirely different.

cheers
john

Hi John.... maybe I put the wrong link... this is the graph I was refering to, in the article , the call it polythene, but on the graph you can see they say plastic

bbc chartcrop.jpg

peace

Post by **John Sayers** » Sun Oct 22, 2006 2:52 am

Ah - I found it - it was on page 4.

thanks

cheers
john