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Which fluffy wool is good behind straddled corner traps? Headphone Amps
Old 23rd February 2011
  #31
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Quote:
Originally Posted by SAC View Post
Simply apply plastic orchard bird netting or chicken wire (etc) to trim sticks inside/behind the cosmetic fabric covered face frame... If this is done along with horizontal screen placed every few feet to segment the larger chamber, you will minimize the total vertical mass that will tend to compress over time, provide additional support, and make it easy to fill and top off each segment with fiber fill. And the various sections of the netting can be opened at the top of each section to fill the absorbent material and later adjusted for any settling.

Don't suppose anyone has a picture of how this looks?
Old 23rd February 2011
  #32
SAC
Registered User
 

Using the 2 foot wall boundary and the 34" face width:

You apply the trim sticks ~1" in from where the face frame would sit - at about the 23 1/4" mark on the wall out from the corner.

A 3/4" face frame will literally attach to these trim sticks via Velcro applied to both surfaces.

Thus, you have 2 triangular trim sticks ripped and placed vertically on the wall so that the leading (forward edge) is angled at 45 degrees so that the face frame will fit flush against it as it straddles the corner. If the corner trap is made as specified, you can simply rip a square piece of 1-1.5" stock diagonally in half to generate the 2 trim sticks. Place the hypotenuse (side) against the wall.

To these trim sticks, you first attach several spaced horizontal pieces of triangular netting (with about 2" extra material on each edge allowing for a fold and stapling) sufficient to form a horizontal barrier in the space. Do this several times to create several vertically spaced compartments.

For each of these compartments cut triangles of orchard netting with sides larger than the size of the triangle space formed by the trim sticks and face frame to allow for the edges to be folded and stapled, attach more plastic orchard netting to the inner edges of the trim sticks 'across the front' such that the triangular volume of the trap is enclosed. For each cavity, leaver about 8-12" open at the top in order to allow a drop panel allowing for insulation material to be loaded.

Fill each compartment with loose insulation and then secure the remaining section of panel - not too securely - you want to be able to have access if/when settling occurs and you made need to top off the fill.

Construct a face frame with one or two cross braces to prevent deformation of 3/4 trim stock. Stretch the appropriate cloth front fabric cross the front and around the side and back and staple the cloth to the rear of the face frame.

On the forward face of the trim sticks. staple several pieces of Velcro 'ribbon', and attach the other half of the Velcro ribbon to the rear of the face frame.

Position the face frame grill and press to attach.
Old 23rd February 2011
  #33
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Hmm. Alright, I think I get it. Thanks for the help SAC
Old 28th February 2011
  #34
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I am moving into a new place and plan on trying out sticking these packed rolls into the corner... is there data on the density of these, and what do you think the difference is between packed and unpacked?

These are the products I'm looking at:
[img]http://www.homedepot.com/catalog/productImages/300/83/83ff308b-76****44e2-b3b4-f0ffcf811706_300.jpg[/img]
not sure if this is the most cost-effective - it may be the bigger bags - but these will stack up into a nice column closer to the ceiling wheras the bags might not fill the whole height as well...

you guys think this is an OK idea? I have to get insulation for the house anyways, might as well cram a bunch in the room and test it out, eh? Also, I imagine the un-opened rolls can be returned easily
Old 28th February 2011
  #35
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Quote:
Originally Posted by Youn View Post
I am moving into a new place and plan on trying out sticking these packed rolls into the corner... is there data on the density of these, and what do you think the difference is between packed and unpacked?
Why not just run Room EQ Wizard (free) to measure your room without them, then put them in the room and measure again. This way you'll know exactly what effect they have. No one here can give you that kind of information.
Old 28th February 2011
  #36
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Quote:
Originally Posted by PaulP View Post
Why not just run Room EQ Wizard (free) to measure your room without them, then put them in the room and measure again.
That's exactly what I plan on doing, and I'll share the procedure and results... just, it's hard to imagine nobody has done something similar before and might know more detailed info... I'm excited to find out either way, of course
Old 28th February 2011
  #37
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Quote:
Originally Posted by Youn View Post
That's exactly what I plan on doing, and I'll share the procedure and results... just, it's hard to imagine nobody has done something similar before and might know more detailed info... I'm excited to find out either way, of course
Make sure you don't move the microphone, even a few inches, while you change setups.

People have used insulation still in its packaging but few, if any, have measured before and after. Sure you hear a difference, but what kind of difference is it ?

It's not easy to get people to run measurement software, and when someone does it's not easy to find anyone willing to discuss the results. I have a few theories...

I look forward to seeing how things turn out for you.
Old 28th February 2011
  #38
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henryrobinett's Avatar
Quote:
Originally Posted by Youn View Post
That's exactly what I plan on doing, and I'll share the procedure and results... just, it's hard to imagine nobody has done something similar before and might know more detailed info... I'm excited to find out either way, of course
I've done this and used both the Pink and the other I got at Lowes. Seems to work great. I'm not an expert and I haven't done measuring so I have nothing significant to add other than unsubstantiated hot air.
Old 28th February 2011
  #39
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vggg
Old 1st March 2011
  #40
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Quote:
Originally Posted by PaulP View Post
It's not easy to get people to run measurement software, and when someone does it's not easy to find anyone willing to discuss the results. I have a few theories...


Let hear those theories! heh

I will definitely post tests once I've rearranged my room. I'm gonna rearrange, add the three bass traps I have (more to come!), and then add the packaged fluffy stuff. I'm planning on making the fluffy into a few corner cubes for the tri corners in my room, but knowing my procrastinating ways...
Old 10th March 2011
  #41
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A couple of things struck me reading this thread....

Several people mentioned how tightly the insulation is rolled when in its plastic wrapper..... Well, a few months ago I bought a few rolls of this for the less conventional (gasp) task of insulating my loft!!! The stuff I had is actually designed to expand when out of the wrapper. Wrapped up it is only around 20mm thick. Take it out of it's wrapper and the compression is lost making the insulation "spring" from go from 20mm to 200mm. So I don't think we are talking about any small amounts of compression here, and that amount of squeezing will surely make it FAR denser and change its gas flow resistivity (guess which other threads I've been reading) accordingly.

RE Post #20. SAC - you mention there would be no advantage to straddling something like RW3 across a corner and then filling the void with fluffy. I've also read elsewhere that it's not best to mix different products in this sense. However, I've also read in many places that filling the void with fluffy WILL help (including Andre @ Post #3. I've even heard people say that things like loose material, blankets, etc. in the void would be beneficial. So I'm wondering whose right here?


Also, for anyone in the UK B and Q have definitely been the best on price for a while now when it comes to loft insulation:

Rockwool DIY Loft Insulation Kingsize Roll 1200 X 2750mm, 5013423234599

Knauf Saver Value Triple Loft Insulation 200mm, 2436978



Cheers

Max
Old 11th March 2011
  #42
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Quote:
Originally Posted by Max Dread View Post
However, I've also read in many places that filling the void with fluffy WILL help (including Andre @ Post #3. I've even heard people say that things like loose material, blankets, etc. in the void would be beneficial. So I'm wondering whose right here?
I went back and reread my post because what you wrote above is NOT what I meant.

#3 is a short post response to a short post. The more complete anwser is "use only light fluffy for the entire absorber."

With lots of fluff,
Andre

Last edited by avare; 11th March 2011 at 03:28 PM.. Reason: Corrected typing errors.
Old 11th March 2011
  #43
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Aaahhh - cheers for clarifying.

So it seems another common, popular - almost taken for granted - "fact" is in dispute here.... I must have read a hundred times, if not a thousand, that in order of most effective first we have:

- superchunk
- corner straddled with fluffy insulation behind
- corner straddled with all manor of other crap behind
- corner straddled with air gap
Old 11th March 2011
  #44
SAC
Registered User
 

Quote:
Originally Posted by Max Dread View Post

RE Post #20. SAC - you mention there would be no advantage to straddling something like RW3 across a corner and then filling the void with fluffy. I've also read elsewhere that it's not best to mix different products in this sense. However, I've also read in many places that filling the void with fluffy WILL help (including Andre @ Post #3. I've even heard people say that things like loose material, blankets, etc. in the void would be beneficial. So I'm wondering whose right here?



I absolutely did NOT say that!!!!!!!!!!!!
And for the record, I completely disagree with the assertion falsely attributed to me.


I said:
Quote:
Originally Posted by SAC View Post
...there is no advantage to mixing acoustical impedances...
I have consistently stated that filling the space adds to the effectiveness of the porous absorber, although a case can certainly be made that the improvement is not a steadily linear one compared to gapped absorbers!

I am sorry that the concept of filling a space with a homogeneous material is so confusing as compared with using a random mixture or materials featuring various acoustical impedance.

To my knowledge I have not disagreed with anything Andre has stated! And may I suggest that you would be wise to read and listen to what he says as well.
Old 11th March 2011
  #45
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Sorry SAC - no offense was intended. I must have misunderstood and/or not explained myself correctly.

I thought what you were saying was that:

- if a corner is filled with "fluffy" (a la superchunk) there's little advantage in straddling something like RW3 in front of it.

- and implied in that is the reverse, that if a corner has RW3 straddled across it there is little point in adding "fluffy" to the air gap behind it.

So I don't know if I misunderstood you and you disagree with these statements, or if I was unclear in my post above. Either way, I didn't mean to misrepresent what you, Andre, or anyone else has said before.

I can't express enough how great I think it is that you guys are willing to spend your time helping people and sharing your knowledge and experience in forums like this. I do my best to read and listen to what you all have to say.....even if I get it a bit wrong or misunderstand occasionally!

Hope this clears things up a little....
Old 11th March 2011
  #46
SAC
Registered User
 

There is no acoustical advantage to spending more money and going to the additional trouble to source the denser more expensive material in front of the large cavity filled with the 'pink fluffy stuff'.

You are a bit ahead financially by simply building a face frame an using orchard netting to contain the less expensive readily available pink fluffy stuff and saving your money.

Save the semi-rigid material for broadband panels where the self-supporting nature lends itself to panels in a bandwidth and an application where its character augments its use in ~4" thick panels and where it is more effective as a mid-high broadband porous absorber.

I am not sure why this continues to be so confusing.
Just how many more times does Andre have to say it?????
Old 11th March 2011
  #47
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avare's Avatar
 

Quote:
Originally Posted by Max Dread View Post
Aaahhh - cheers for clarifying.
You are welcome.

Quote:
So it seems another common, popular - almost taken for granted - "fact" is in dispute here.... I must have read a hundred times, if not a thousand, that in order of most effective first we have:

- superchunk
- corner straddled with fluffy insulation behind
- corner straddled with all manor of other crap behind
- corner straddled with air gap
Where? "Superchunk" and "corner straddled with air gap" ARE ALL that have been presented for home studio construction by professionals. Beyond that random combing of materials IS NOT recommended. The combination of various density materials has little advantage acoustically, when properly designed, and is invariably more expensive.

SAC summed it up well in post previous to this one.

Andre
Andre
Old 11th March 2011
  #48
SAC
Registered User
 

In fairness guys, I think what has happened is that a few proposals have initially been proposed, and, as so often happens here, folks like to propose their imagined 'improvements' or variations on a theme, thinking that if one method is good, then a variant will be even better.*

And before you know it, the place is filled with beau coup topologies (erroneously) assumed by many to be roughly equivalent.

Now don't get me wrong. I like thinking and experimenting! But before one posits an alternative method as, well, 'equivalent' or better, one would do well to get the basics down. And then, if you want to posit another alternative, do a bit of due diligence and a bit of research, and in the process you may come up with a new founded method, or, as in many cases we routinely see presented, one may discover the reason such an idea has not have been posited before.

And if one would simply avail themselves of the D'Antonio and Cox text Acoustic Absorbers and Diffusers, most of these issues are addressed in quite some detail! So you really don't have to waste time to reinvent the wheel. And before anyone says it, I know the book is expensive - but that is a problem that the Inter-library loan program solves!

*Here's an example of such an instance that thankfully was thankfully damped - not that you really have to do far to find them!
Old 15th March 2011
  #49
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Quote:
Originally Posted by localhost127 View Post
does anyone have any photos of their ultra thick pink fluffy traps?
7' tall, 34" across the face. The front was covered with a nice black fleece but I don't have any finished pics on my phone.
Attached Thumbnails
Which fluffy wool is good behind straddled corner traps?-trap-empty.jpg   Which fluffy wool is good behind straddled corner traps?-trap-filled.jpg  
Old 15th March 2011
  #50
SAC
Registered User
 

By gosh! I think he's gone and done it!
Old 15th March 2011
  #51
Gear Nut
 

Yes, that makes sense. BTW, how much fiberglass was needed to do those traps? What R-value?
Old 15th March 2011
  #52
SAC
Registered User
 

Quote:
Originally Posted by localhost127 View Post
sorry if this was stated before, but are the rolls considered too dense in their packaged (rolled in plastic) form? do they need to be unrolled and then loosely filled into the cavities to be most effective?
In response to the earlier posted concern...

Some are highly compressed! While wandering around the local big box home improvement center, some of the rolled 'pink fluffy' insulation is indeed tightly compressed, and removing it from the packaging would indeed be beneficial.

In fact, some of the rolls here were so compressed that you could punch them and they would hardly dent. That is too compressed.

So, one would do well to examine the nature of the rolls. If they are very tightly compressed, then need to be 'released'. If they are only lightly bound, then they might be OK. But from what I have examined, I would suggest removing them from the packaging. If one wants to then re-encase them in the same rolled format but with less compression, still allowing them to be stacked, that could work as well.

In any case, you do not want them highly compressed - which I suspect is just the opposite of what the manufacturer wants in terms of shipping size efficiency.



.....

Oh, and I almost forgot - JohnsManville makes batts that are pre-encased in plastic that are intended to be installed that way - meaning the plastic allows for the material to fluff to its maximal thermal effectiveness without compression. For those convinced they will die otherwise, this would seem to be better than the tightly compressed plastic wrapped products others are advocating from both a handling point of view and for use in corner bass traps. Note, the multiple barriers would do well to be modeled in Soundflow, but I doubt they will adversely effect the LF performance too substantially. (Note - I am completely prepared to be disproved on this!)
Old 15th March 2011
  #53
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I used two and a half rolls of R-30 (15"x9.5"x25') to build four of these traps. Each trap holds 10 wedges. I used a few long nails inside the frame to help the bottom wedges from getting too compacted under the weight of the fiberglass above.

These traps, BTW, were inspired by Bountytracker's build. I just slimmed down the frame a bit to keep it as light as possible.
Old 16th March 2011
  #54
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Quote:
Oh, and I almost forgot - JohnsManville makes batts that are pre-encased in plastic that are intended to be installed that way - meaning the plastic allows for the material to fluff to its maximal thermal effectiveness without compression. This would seem to be ideal from both a handling point of view and for use in corner bass traps. Note, the multiple barriers would do well to be modeled in Soundflow, but I doubt they will adversely effect the LF performance too substantially.
SAC - Are you referring to the following????

Poly-Encapsulated - Insulation Products

Thanks.
Old 16th March 2011
  #55
SAC
Registered User
 

Yes.

But let me also issue my own disclaimer lest I later be quoted as saying I endorse batts or rolls left in plastic packaging!

I am NOT a fan of mixing barriers among absorption and creating additional radical changes in acoustical impedance, nor am I a fan of helter skelter applied barriers expecting them to uniformly reflect the full spectrum.

BUT, if one is insistent upon wrapping a batt in plastic as a result of being convinced that they will otherwise die, at least these are not overly compressed as a majority of the retail batt and roll packages are that I have examined and that others seem so quick to want to use.

So, bottomline - these would be better then the tightly compressed wrapped rolls. But for the record, I am not a big fan of wrapping.

(I rather feel like I am acting as an enabler to help provide alcohol to an alcoholic instead of directing them to remain sober!)

heh

Where this product seems like it might be a reasonable option is IF you can source it in a sufficiently high R value such that the thickness of the uncompressed fiber extends to beyond 20 inches - without introducing multiple intermediate plastic barriers IF, and this is a big IF, you can find the product such that uncompressed the plastic envelope expands to beyond a 20" thickness this may be a useful and practical product.
Old 21st March 2011
  #56
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For all german users, Isover Acustic TP1 with a nominal linear gas flow resistivity of 5 krayls/m comes in uncompressed packages that are 20" or 50 cm thick. One package with the size of 48 x 24 x 20 inch³ or 120 x 62 x 50 cm³ is 15 EUR or the like.

While cutting more expensive boards into diagonals for superchunks saves material, costs and space the priorities may change if the material itself is cheap. In order to have better absorption I mostly used full packages in the corners (if I used broadband absorption at all). The only 'problem' if this is any is that you need one trip to the building store for one or two light packages depending on your car size
Old 21st March 2011
  #57
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Quote:
Originally Posted by Hannes_F View Post
For all german users, Isover Acustic TP1 with a nominal linear gas flow resistivity of 5 krayls/m comes in uncompressed packages that are 20" or 50 cm thick. One package with the size of 48 x 24 x 20 inch³ or 120 x 62 x 50 cm³ is 15 EUR or the like.

While cutting more expensive boards into diagonals for superchunks saves material, costs and space the priorities may change if the material itself is cheap. In order to have better absorption I mostly used full packages in the corners (if I used broadband absorption at all). The only 'problem' if this is any is that you need one trip to the building store for one or two light packages depending on your car size
Something like this? Just some fabric on top of the plastic and I´m done thinking about my room´s corners?

Old 21st March 2011
  #58
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Quote:
Originally Posted by JulianFernandez View Post
Something like this? Just some fabric on top of the plastic and I´m done thinking about my room´s corners?

No, this is compressed material. In compressed form it will be quite reflective for the bass, and also the bass waves will float around the column. What you want are big, closed surfaces, flat to the walls, and no acoustical shortcuts.

The uncompressed stuff that I mean looks like in the attached pictures.

BTW I personally would always run measurements and performance tests before putting fabric on anything.
Attached Thumbnails
Which fluffy wool is good behind straddled corner traps?-isover-akustic-tp-1-60-mm-6-25-m-id2413357.jpg  
Attached Images
Which fluffy wool is good behind straddled corner traps?-64_1218365246_hoved.jpg 
Old 21st March 2011
  #59
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Quote:
Originally Posted by Torea View Post
Don't suppose anyone has a picture of how this looks?

I'll be making mine soon, have the insulation, have the plans, need the wood for the frame. So sometime in the next week or two, I should have pictures and tests to post =)
Old 21st March 2011
  #60
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Quote:
Originally Posted by SAC View Post
There is no acoustical advantage to spending more money and going to the additional trouble to source the denser more expensive material in front of the large cavity filled with the 'pink fluffy stuff'.

You are a bit ahead financially by simply building a face frame an using orchard netting to contain the less expensive readily available pink fluffy stuff and saving your money.

Save the semi-rigid material for broadband panels where the self-supporting nature lends itself to panels in a bandwidth and an application where its character augments its use in ~4" thick panels and where it is more effective as a mid-high broadband porous absorber.

I am not sure why this continues to be so confusing.
Just how many more times does Andre have to say it?????
...sorry Andre and SAC,

I just read this. In my little project I was going to stick saddled 2 foot wide 6" roxul in my back of speakers corners. I also read that these traps wouldn't attack the "lower" frequency bands (my main concerns are 50 and 80hz). So, I picked up regular 6" deep insulation and wire to fill these corners before placing the traps I built as I read the "fluff" addresses lower frequencies. Here I was planning today about how I was going to add slats of wood over the top of these absorbers to help keep some mid or high end in, then this...ouch.

Should I use the "fluffy" in other corners because it will not do anything adding to the corner I plan to straddle? Should I put the "fluffy" in those corners instead, get out my sawzall and cut the 8' traps I built in half to place elsewhere?

I'll reread again, but are you saying, adding the fluff will do nothing for the lower frequencies I'm going after if I put the Bass trap over it. But will address those frequencies if I remove the bass trap?

Sorry for being so dense.
Thank you.
Rich
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