Absorption Data - Four Devices

[Scott R. Foster]

The data has finally arrived!

See the post at

http://forum.studiotips.com/viewtopic.php?p=3975#3975

in the "Treatment" section of the FAQ

[avare]

Thanks (in alphabetical order) Auralex, Eric and Jeff!

[Dan Nelson]

How wide is the linear foot of corner? Interesting how close the the foam and glass wool are in absorption. Nice work guys


Edit I found it 34" for the LENRD's and the Super chunks

24" for the MiniTraps and Corner absorbers

Dan

[Scott R. Foster]

The running length of all four devices was 8' measured along the run of the corner. OTOH, the face width dimension of the devices varies.

MegaLENRD's have a 34" face width, as does the Studiotips SuperChunk [SSC] - the Studiotips Corner Panels [SCP] and the MiniTraps have a face width of 24".

See these links for more details on dimensions.

http://www.auralex.com/bass_traps_mg-le ... -lenrd.asp
http://www.realtraps.com/minitraps.htm
http://forum.studiotips.com/viewtopic.php?t=534
http://forum.studiotips.com/viewtopic.php?t=535

Important to note however is that the absorption data is not presented per SF of exposed surface, or using any other measurement discreet to one particular device, but rather the absorption data is presented per center frquency per linear foot of corner.

Thus given a known length for the corner areas one wishes to treat, and material price and labor estimates for all four choices, one can derive a rational bang per buck index for each device and compute a time / effort / money budget that fits your own particular needs and abilities.

[Savant]

First, thank you to Scott for putting this data up.

Second, I would like to apologize to y'all for the long delay. As shown in the files, the measurements were conducted on March 9, 2004. Eric, Scott and I have been deliberating for the past three months on the best presentation. Auralex - I will admit - had a hand in the timing since we needed to review the sensitivity of some of the information prior to releasing it to the public. What I hope we have here is some definitive answers. We worked very hard to minimize anything that could be construed as "questionable data manipulation." The end result is something, I believe, will go a long way to answering questions.

But this is only the visible apex of the large, floating, mostly submerged oceanic body of amorphous hydrogen dioxide in its solid state.

We (Auralex) will be undertaking studies like this periodically, so if you have thoughts on future work, please debate them in these pages. Scott can moderate and I will defer to him (or Eric or Dan) as the final say on "what to do." (Just keep in mind that resources are not unlimited! :-)

Thank you all for your patience throughout this process.

[Guest]

Jeff,
With a lot of thanks and respect for your attitude.
Clear is that Jeff as Auralex did something that certainly not serves Auralex's purposes other than being scientific honest and sharing.

Scott,
You're a real friend, many thanks for everything you did and do.

Dan,
It's in respect for of all the work that you've done for us, the forum and the distribution of acoustic science that we choose the name studiotips for the corner absorbers. They match the mother site.
You're the mother.

All,
Many thanks for being such a nice and supportive bunch of guys.

Avare thanks for your kind and stimulating words, but don't forget Scott :):)

Eric

PS: the order is random (I'm not very organized)

[Bob]

Cool stuff.
It certainly answers the question "is there any point to making it solid instead of just 4" across the front". The answer is make it solid.

Any idea why they all have a peak at 100hz? (11.3')

Some of them are full, some of them are hollow, and some of them are 24", some of them are 34". I would have expected the 34" solid ones to have a lower peak. Is the solidness doing absorbtion, where the 24" ones were being membranish?

I'd never heard of megaLENRDs (obviously I'm a little behind in reading acoustology by Jeff), but the relative absorbtion of the others, except for the 100hz peak, was pretty much what I expected.

It looks like there's a minor peak around 630hz too. Perhaps a room effect?

[Scott R. Foster]

Bob:

While I agree there is "a point" to making em solid, they are gonna cost a bit more. If you are looking on a tight budget, the Sabin numbers on a Supertips Corner Absorber aint nothing to sniff at IMO. The effectiveness of these units is downright amazing when you consider the cost. It is a matter of a little bit of the right stuff in the right place going a long way to getting the job the done. You gotta find that appealing. If you can find a few "volunteer" wall / ceiling insulation scraps for the cavity all the better.

On the topic of costs for these units, does anyone have current cost data on 703?

I would like to see someone calculate the material costs of the two Studiotips designs using current prices. Also, can anyone provide sums from their recent experience as to material costs for the cloth cover and frame work behind their recent production and installation of such a unit[s]. Additionally, your estimate for the time required to construct would he informative.

FWIW I found an internet "best price" of about $180 [shipping costs included] for enough MegaLENRD to treat 4' of corner - or about $45 per linear foot of treatment. Given the ease of installation for these units, that's pretty attractive.

* edited to correct the dimensions quoted for the MegaLENRD's

[Bob]

Approximate costs for 2" 703 seem to range from $0.50 US to $1.05 US /ft^2.
I'll split the difference to $0.75, and assume that the DIYer can go pick them up (no shipping).

Some wood framing and nails should be $10
I found 36"x8' of burlap for $20 in a tan colour (or $35 if you want black)

Studiotips Corner Panels are 4" 8' tall would be
0.75
x 2 (to get to 4")
x 8 (to get to 2'x4')
x 2 (to get to 8')
= $24 per (for insulation)
+ $30
= $54

Studiotips SuperChunk
0.75
x 2 (to get to 4")
x 8 (to get to 2'x4')
x 6 (the number of sheets the PDF said were needed for 8')
= $72 per (for insulation)
+ $30
= $102

[Guest]

Cool stuff.
It certainly answers the question "is there any point to making it solid instead of just 4" across the front". The answer is make it solid.

Any idea why they all have a peak at 100hz? (11.3')

Some of them are full, some of them are hollow, and some of them are 24", some of them are 34". I would have expected the 34" solid ones to have a lower peak. Is the solidness doing absorbtion, where the 24" ones were being membranish?

Bob in the future more.....
While this membranish looks that way, it seems more complicated.
We also have data contradicting that approach.
Other data will show that even when fully solid it just about behaves as the hollow versions.

Corner absorption really needs much more study.
So don't draw explicite conclusions. The data we have, and I have from many years back doesn't allow it.

Eric

[avare]

Relating to insulation prices...

Prices are in Canadian Dollars.

Roxul RXL-40, 4" thick: $1.28/ft^2 (42 cents per inch thickness)
Roxul "Safe'N'Sound" 3" thick, 2.5 lb density: $0.47/ft^2 (16 cents per inch thickness)

Multiply by 0.75 to get roughly American Dollars.

The second item comes to about one fifth the cost of 703!

[Savant]

Scott,

FYI on MegaLENRDs: MSRP for a box of two (2) units (= 4' of corner) is $259.00. "Street" price is usually lower. I think you may have found a good price on a box of 2 units, but remember that the units are only 2' tall - not 4' tall.

Just wanted to clarify.

[Scott R. Foster]

Approximate [material] costs for...

Studiotips Corner Panels... 4" x 8'... = $54...

Studiotips SuperChunk... = $102....

Thanks Bob... I'm going to bump your $10 figure for other parts up a tad [to cover primer, trim paint, adhesive / fabric fasteners, etcetera] and round those costs off in my head to $56 and $105 per 8' corner for the SCP and the SSC respectively. Thus, I generate SCP = $7.00 plf and the SSC = $12.50 plf .

I'd like to additionally formulate a consensus on the labor component - if not its value, I'd at least like to quantify the task in a temporal context.

From my experience I'd say that for 4 corners in a room with 8' ceilings it would realistically require at least one day's work to get from driving out to pick up materials [mineral wool, hardware, paint, lumber / trim, fabric...] to finishing off the trim - yielding 32 linear feet of cloth covered SCA or SSC. I say it'll take "a day" but it might be a "long day"... call it 10 hours?

A related question would be what does it take to install a stack of MegaLENRD's ? Is it just a matter of stacking em up with a sprits of adhesive to tack em to the wall? If so, I think I would spend more time cleaning out the corners of my control room than on the "installation" process. Also given that many suppliers carry Auralex products you might be able to do just as you suggest with the 703 and order from a local shop and pick em up yourself.

How about MiniTraps - are these hung on hardware provided with the units or are there additional costs. How much work is involved? The best price identified so far is $159.99 per 4' of treatment plus shipping from:

http://www.avsforum.com/avs-vb/showthre ... ost3250677

You must join this group [free] and must buy at least 4 units to get this price.

Using these figures and assumptions, and applying them to the example room described above, I get all in cost of :

SCP's = $224 plus labor = 32 lf x $7+ 1 long day

SSC's = $400 plus labor = 32 lf x 12.50 + 1 long day

MegaLENRD's = $1320 = $165 x 8 [plus shipping ???]

Minitraps = $1279.92 = $159.99 x 8 [plus shipping / installation ???]

If anyone can modify these assumptions from their experiences, please do.

Also, are the MegaLENRD's and/or MiniTraps fire rated? If this is desired / required, i think this can be accomplished as to the studiotips units pretty easily - looks to me this "FABRIC SEAL" stuff it'd do the trick for a bit more than $1 per lf on the example project.

http://www.flameseal.com/prices.htm

*edited to adjust prices on the MegaLENRD's & MiniTraps sans shipping

** adjustment should also be made for sales tax if bought "in State" versus shipping costs

[Savant]

Scott,

• The most reasonable method of installing MegaLENRDs is to stack them. No fasteners or glue should be necessary. We have had folks build shelves for them to stack on top of in situations where they wanted a smaller number of them with a higher ceiling - e.g., 8' of "traps" up high in a room with a 12' ceiling. In every room I have every used them in, I have simply stacked the appropriate number of units and left any gap at the top. While arguably not "ideal," it takes all of about 16 minutes to do for four corners.

• All Auralex Studiofoam stock (from which the MegaLENRDs come) is rated "Class B" for flame retardancy. More information is available on our website. (Look under the FAQs.)

Hope this helps.

[Scott R. Foster]

Scott,

FYI on MegaLENRDs: MSRP for a box of two (2) units (= 4' of corner) is $259.00. "Street" price is usually lower. I think you may have found a good price on a box of 2 units, but remember that the units are only 2' tall - not 4' tall.

Just wanted to clarify.

Ahhh... thanks, I was reading the web'vert incorrectly - I thought it was 2 x 4', I see now it's 4' of treatment per pack [2 x 2'].

And yes - it pays to shop - this was the best price I could find - and it was not published, but rather provided upon my request for a quote of the merchant's best price for 4 boxes of the product. Like most esoteric goods, I find that acoustic specialty products [especially when purchased from from smaller shops] generally have two prices - the list price, and the best and final price - well at least two - sometimes more than two if the order is large enough.

*edit

Also to be entirely rational about the purchase one would probably look hard at some of the package deals that this type of product comes in... seems you can save quite a bit using this method of purchase ... I refer to stuff like this:

http://www.sweetwater.com/store/detail/RoomDST240B/

I looked, but didn't see an Auralex room package that contained the MegaLENRD's - do they exist?

Thanks

[Bob]

Avare:

Of course we don't have absorbtion coefficients for it, so this is only peripherally relevent here.

Roxul "Safe'N'Sound" 3" thick, 2.5 lb density: $0.47/ft^2 (16 cents per inch thickness)

Studiotips SuperChunk, unknown absorbtion, made with Roxul "Safe'N'Sound"
$0.35/ft^2 US.
x 8 (to get to 2'x4')
x 96" / 3" / 4 (8' = 96", each sheet is 3" thick, and 4 triangles per 2'x4')
= $22 per (for insulation)
+ $30
= $52

So, rounding up, for four corners that's $220 US.

[Bob]

MiniTraps are $159.99 each.
(joining AVS is free)

http://www.avsforum.com/avs-vb/showthre ... ost3250677

So
Minitraps = $1279.92 = $159.99 x 8 [plus shipping / installation ???]

[Paul Woodlock]

Greetings

I'll price up the Studiotips Corners Traps UK Version as asoon as I get time. Which will probably be sometime over the weekend.

I currently have a session, and then I gotta dig a hole in the garden to dump any excess concrete from tomorrow's floating floor pour. And then I gotta goto bed extremely early!!!


Paul

[avare]

Ignore my email.

Avare:

Of course we don't have absorption coefficients for it, so this is only peripherally relevant here

At least we are mostly working off of one (internet) page. I am taking your remark as a great compliment to your data you have compiled. You know better than anyone what is there, but there is so much there that even you couldn't remember all the products

It is on your coefficients page, about a third of the way down. The numbers are similar to 703 type materials.

[Bob]

Avare:

Hotmail Email ignored.

For absorbtion coefficients that we don't have, I meant we have neither absorbtion nor sabin data for Safe N Sound mounted across a corner or filling a corner.

The numbers are similar to 703 type materials

Which implies to me that the corner mounting might give similar results, and since it's SO much easier to get Safe N Sound than 703 it would certainly be worth a try. But there's no measurement data.