DIY Broadband Absorber - pictures posted

[nukmusic]

I've wanted to try out the filled 703 corner thing, but I wonder if adding fiberboard or MDF in between each layer of 703 would trap more bass?? Kinda like a non hanging "Bass Hanger"





or maybe even stuffing pipe with 703 (and maybe fiberboard strips) vs leaving it hollow.


or maybe sandwiching a 2x4 piece of fiberboard in between the DIY broadband panels



links:
http://www.teresaudio.com/haven/traps/traps.html
http://www.johnlsayers.com/phpBB2/vi...t=bass+hangers
http://www.radford.edu/~shelm/acoustics/bass-traps.html

[TheSweetener]

Originally Posted by airmate

now i made a measurement with fuzzmeasure.

i've recorded a sinus sweep through this chain:
brauner phantom c -> mogami 2791 -> chandler tg channel mk2 (eq not engaged) -> rme multiface @ 96 khz

the microphone was put in my listening position between the speakers.

i'll see if i can organize more accurate equipment for further measurements soon.

and this is it:

Hi!
I think you should use a omni mic to get proper results. At least that's what I do.

[Ethan Winer]

Michael,

> Most of the people I see making panel absorbers for corner traps look like they are sealing the sides, top and bottom of the traps so no air can leak around them. <

That's a completely different type of bass trap. Here's my take on that design, from my 1995 article in Electronic Musician magazine:

www.ethanwiner.com/basstrap.html

The advantage of a sealed membrane trap is it can work to a pretty low frequency without sticking out much from the wall. Another potential advantage is it's a bass trap only, so you can put as many as you want in a room without also adding more mid/high frequency absorption. The downside is it's a tuned design, so you need two or even three different depths to target the entire bass range.

> This is a pressure type of panel I would assume that is causing the sound waves to have to fight to work through the 703 <

This type of trap does work on pressure, but it acts more like a "shock absorber" for sound waves. In this case the rigid fiberglass inside serves to damp the panel's vibration so it doesn't continue to ring when the source sound stops. The rigid fiberglass also lowers the Q so the trap can absorb over a wider range of low frequencies.

--Ethan

[not_so_new]

Originally Posted by Ethan Winer

Michael,

> Most of the people I see making panel absorbers for corner traps look like they are sealing the sides, top and bottom of the traps so no air can leak around them. <

That's a completely different type of bass trap. Here's my take on that design, from my 1995 article in Electronic Musician magazine:

www.ethanwiner.com/basstrap.html

The advantage of a sealed membrane trap is it can work to a pretty low frequency without sticking out much from the wall. Another potential advantage is it's a bass trap only, so you can put as many as you want in a room without also adding more mid/high frequency absorption. The downside is it's a tuned design, so you need two or even three different depths to target the entire bass range.

> This is a pressure type of panel I would assume that is causing the sound waves to have to fight to work through the 703 <

This type of trap does work on pressure, but it acts more like a "shock absorber" for sound waves. In this case the rigid fiberglass inside serves to damp the panel's vibration so it doesn't continue to ring when the source sound stops. The rigid fiberglass also lowers the Q so the trap can absorb over a wider range of low frequencies.

--Ethan

Hey Ethan thanks again!!! You rock.

Broadband for me thanks....

So the best solution is a non-sealed stack of 703 (or something what is best??) with a sonically transparent covering and the next best solution is a sheet of 703 (or something what is best??) attached to the wall and dressed up with a sonically transparent covering. Do I have this right?

I have 5 of your traps and they helped a whole lot but I stil have issues with 60 and 120 in my room (higher too but not as bad).

[Ethan Winer]

Michael,

> So the best solution is a non-sealed stack of 703 (or something what is best??) with a sonically transparent covering and the next best solution is a sheet of 703 (or something what is best??) attached to the wall and dressed up with a sonically transparent covering. <

I prefer 705 over 703, though non-sealed is best for most rooms as you suggest.

> I have 5 of your traps and they helped a whole lot but I stil have issues with 60 and 120 in my room (higher too but not as bad).

Yeah, five bass traps is not really enough for any room. I have 20 in my home studio, and 38 in my living room!

--Ethan

[Scott R. Foster]

Originally Posted by nukmusic

I've wanted to try out the filled 703 corner thing, but I wonder if... snip

No. You're looking at the real deal. Don't outsmart yourself.

You start fooling around and you are gonna "tune" a near perfact broadband absorber into god only knows what... let simple but effective be your friend.

My $0.02

[airmate]

Originally Posted by TheSweetener

Hi!
I think you should use a omni mic to get proper results. At least that's what I do.

yes, you're right, thank you...! i've already figured that out myself. i was wondering about the weird HF response, but then i realized that this must be due to the cardioid pattern...

[not_so_new]

Originally Posted by Ethan Winer

Michael,

> So the best solution is a non-sealed stack of 703 (or something what is best??) with a sonically transparent covering and the next best solution is a sheet of 703 (or something what is best??) attached to the wall and dressed up with a sonically transparent covering. <

I prefer 705 over 703, though non-sealed is best for most rooms as you suggest.

> I have 5 of your traps and they helped a whole lot but I stil have issues with 60 and 120 in my room (higher too but not as bad).

Yeah, five bass traps is not really enough for any room. I have 20 in my home studio, and 38 in my living room!

--Ethan

So where did you get them from?

(just jokes Ethan, thanks again for everything).

[Joel DuBay]

8-12 traps (total) will help you see a more noticeable difference, but depending on what you get..... may not help with the 120 frequency issue. Again, depending on what type of traps you purchase or build...

Do your research.





Joel

[euphonic]

Hi

I'm new to this board.

I really like this kind of absorber made out of an ikea bookshelf - great idea, airmate.

Maybe the acoustic-cracks can tell me if i can use this kind of foam instead of hemp or rigid fiberglass?
(sorry if this is in german, but I did't find anything comparable in english)

http://www.schalltechnik-mm.de/konfi...Skin_30_50.pdf

Thanks a lot.

[Markd102]

Slightly off the topic, but can anyone tell me.....

Are there ANY acoustic advantages to hanging curtains?

[Joel DuBay]

Originally Posted by Markd102

Slightly off the topic, but can anyone tell me.....

Are there ANY acoustic advantages to hanging curtains?

The short answer is yes. However, that can be as limiting in the bands it will affect as it will in any absorption at all. If you look to Sound On Sound for experimental acoustical ideas, you'll see Paul White recommending a double duvet to cover a wall or window area and to help with early reflections. However, broadband absorption with rock wool (readily available in all parts of Australia, except Arnam Land) is a much, much better choice.

Where are you mate?

I may be able to help you source it there through our dealer in Melbourne.


Cheers,

~ Joel

[Markd102]

Hey Joel, it's Mark (Watershed).

I'll talk to you about it on Messenger.

[sardi]

Originally Posted by not_so_new

attached to the wall and dressed up with a sonically transparent covering.

So I dug this up cos Im in the middle of building sum Rockwool absorbers, and the only thing I cant find any info on is what to cover the traps with.

Im hoping someone (possibly Ethan) can tell me the best (and obviously cheapest) material to use to cover these things.

I live in Australia too, so no uber fancy yank stuff.

Big up to the wealth of info on this some what tricky subject.

Cheers.

[sardi]

Also, what wood do you reccomend for the frames?

Ive heard of a lot of people using Pine. Is the lightest wood best for the job? Obviously these things need to be hung so Im trying to make them as light as possible.

Many thanx.

[TanTan]

i've never been more confused , this base traps issue is such a voodoo ...
i need to place bass traps on all my studio's corners and i just don't know which way to go , i'm looking for the best results and i can't make up my mind between:

- Ethan's Mondo\Mini traps
- DIY - bass traps
- DIY - super chunk bass traps
- Auralex LENRDS
- RPG modex \ corner modex

what would you do ???

[Youn]

super chunks or ethans traps, one requires more work and less money, but both seem to do a good job for a number of people.

I personally made my own framed absorbers, various sizes (2x3, 2x4, 3x3, 3x4 - 6 inches thick, 12 "traps" all together) for portablity and configuration variations mostly. I couldn't stack two 2x4 on top of each other to go floor to ceiling, mine's just shy of 8 feet. Also, the smaller ones I can easily move around the room and place wherever, they are thick enough so they stand up by themselves. It cost around 300-400 dollars and maybe three or four days of work altogether. Actually I've only finished 8, but yeah I've noticed a difference, though surprisingly other people walk in and say it sounds wonderfully different, not initially knowing the traps were there.

Super chunks would work equally well, cost less because no "frames" are required, and is more then likely alot less work then what I did. Oh, don't forget GIK traps, which are similar to what I've done but probably better, and don't cost that much more then DIY.

[sardi]

BUMP.

Anyone?

Originally Posted by sardi

So I dug this up cos Im in the middle of building sum Rockwool absorbers, and the only thing I cant find any info on is what to cover the traps with.

Im hoping someone (possibly Ethan) can tell me the best (and obviously cheapest) material to use to cover these things.

I live in Australia too, so no uber fancy yank stuff.

Big up to the wealth of info on this some what tricky subject.

Cheers.

[Glenn Kuras]

Originally Posted by sardi

BUMP.

Anyone?

Berlap is a good fabric to use.. It does not look as good but will work.. I know of some guys that have used spray glue to rap it with.. Seems to work pretty well..

Glenn

[Ethan Winer]

Sardi,

> Im hoping someone (possibly Ethan) can tell me the best (and obviously cheapest) material to use to cover these things. <

I agree with Glenn that Burlap is about the least expensive but effective covering you'll find. In England they call it Hessian, in case you're not familiar with the term burlap. The usual color is potato sack brown but most fabric stores have a variety of other colors to choose from.

--Ethan

[digibird]

Originally Posted by Ethan Winer

Sardi,

> Im hoping someone (possibly Ethan) can tell me the best (and obviously cheapest) material to use to cover these things. <

I agree with Glenn that Burlap is about the least expensive but effective covering you'll find. In England they call it Hessian, in case you're not familiar with the term burlap. The usual color is potato sack brown but most fabric stores have a variety of other colors to choose from.

--Ethan

When pricing burlap and other fabrics, I considered painter's drop cloth from Home Depot as well - pretty cheap per sq. ft. when buying 12'x15' sheets to cut to size. If you don't buy real thick cloth, you can still blow air thru it - is this a reliable test of the fabrics' acoustical transparency?

The unbleached, natural fabric has a nice look to it, taupe in shade.

What do you think of this option?

[juniorhifikit]

just go to the cheap section of the fabric store and start "listening" to the fabric. If you can't "hear" the fabric, it'll probably do nicely. A little "stretchyness" can go a long way toward eliminating wrinkles and sag. I've always used a staple gun on the back side of the frame to adhere the cloth.

[Joel DuBay]

Originally Posted by juniorhifikit

just go to the cheap section of the fabric store and start "listening" to the fabric. If you can't "hear" the fabric, it'll probably do nicely. A little "stretchyness" can go a long way toward eliminating wrinkles and sag. I've always used a staple gun on the back side of the frame to adhere the cloth.

I profoundly agree with looking for something that stretches, even a little bit like trico, peachskin fabric, etc....

Canvas, as most painters know, takes a LOOOOONG time to stretch correctly, and the process for doing it right, and ensuring it will not stretch OUT, is a challenge, chore and headache. Get some stretch bro.

Also, when speaking of acoustical transparency, consider that the most important consideration when choosing fabric is whether or not you like it, it is useable long term and provides "some" breath ability. The “breath ability” is not likely to be an important factor for most rooms as you do not want to deaden a room too much with fabric featuring really loose airflow. However, fabrics like thick, un-stretched canvas used to cover acoustical materials with any moisture content have a better chance to create mold. Mold=bad.

Semi transparent (slightly stiffer airflow) fabrics typically allow for lowend absorption and no menacing and harmful mold build up. They look HELLA better a year later too.

Once again, using a solid stretch fabric ensures the contents of your traps will not leech out, and that your traps will maintain a sharper, more usable appearance, longer. In some cases, (like with our fabric) the absorptive properties (or lack thereof) can enhance low frequency absorption.



Good luck, and VIVA LA DIY!

Joel DuBay Sr



Ready Acoustics LLC
NOW, FREE 3D Acoustic Analysis of your ROOM!

[orange]

I got pretty cheap fabric from Ikea that was suitable.

[gjuodenas]

Originally Posted by nukmusic

I've wanted to try out the filled 703 corner thing, but I wonder if adding fiberboard or MDF in between each layer of 703 would trap more bass?? Kinda like a non hanging "Bass Hanger"

I have been installing bass trap hanging panels just like these for years, they work great. I usually hide them above a false control room ceiling.

[Scott R. Foster]

When pricing burlap and other fabrics, I considered painter's drop cloth from Home Depot as well - pretty cheap per sq. ft. when buying 12'x15' sheets to cut to size. If you don't buy real thick cloth, you can still blow air thru it - is this a reliable test of the fabrics' acoustical transparency?

If you can breath through it, it'll work. Shop for price and aesthetic appeal - and as Joel points out, a bit of stretchy can make it a easier to get a sharp look - especially if upholsterery aint your forte.

[StrykeBack]

wow. I'm glad I stumbled onto this thread. With all the talk i've had about gear upgrades the one things I haven't worked on too much is acoustics. But i've got some heavy duty moving blankets doubled up i sowed together and then hung from a curtain rod behind me that doubles to cover reflections off of these 9 foot tall double french glass doors behind me (plus so i can have a little privacy to get dressed or have the girlfriend over )

Anyways I studied acoustics a little bit while in recording school and found it really interesting but my bedroom/ mixing/overdubbing room has a lot of odd shapes or glass that i need to bring into account when figuring out where to place some traps or obsorbers. I saw the program available on Joel's company website but before i buy...can anyone tell me thats tried it if i can take say a closet at one end of the room and the double glass doors covering another wall into account in this program? or even gear placement such as dressers or desks?

Just looking for a program that can help me lay out everything i need.

[clusterchord]

fantastic work , airmate. looks really nice.


im going into diy broadband myself, so i found this info valuable. q: did u buy hemp from manufacturer direct, or are there are dealers for this?


im also very concerned about microparticles and health issues - so i was wondering, is Owens Corning, and other similar products/mateirals not good enough in this regard ??

if such mineral does leek particles, im thinking, is a thin fabric really gonna stop it go in my room ??

[airmate]

clusterchord, i bought the hemp directly from the manufacturer.
it's a company in bavaria that has some partners all over germany. so they sent the hemp to a hardware store in my city they regularly supply with goods. and this store sent the hemp to my place.

here is some english information from the hemp manufacturer (pdf file):

http://www.thermo-hanf.de/upload/pdf...t_2004_ENG.pdf

("hanf" means "hemp" in german language)...


btw: i had a look at your website - my girlfriend is croatian as well...

[cajonezzz]

Nice clean work man!!!

I didn't have the patience to so mine that clean, but they are working. 4 inch rockwool wrapped in black speaker cloth. 2x4 panels. I've got 16 of em in a 14x16 room, and I'm adding another 6 MiniTraps this week....