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703/705 Alternatives for acoustic traps? Dynamic Microphones
Old 28th June 2006
  #1
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703/705 Alternatives for acoustic traps?

Ok ......

If you've seen my recent posts, I've been doing a bunch of research on tuning my room correctly. Fabric, materials, placement etc, etc .....

As of now my plan is to double up 705 to a thickness of 4" in the corners of my room .... the outside layer will have frk the inside layer will not. Also, I'll be building some absorbers for the direct reflection points and behind the nearfields (no frk). Behind the mix position will be a large 4 ft rack (nothing I can do about that) and a thick curtain on the window in the back of the small room.

Also, I plan to put a 1-2" thick cloud above the mix position say 4' x 6'.

I'm looking at $605 usd for fiberglass alone ....... then fabric, paint and any gizmos/hardware to hang em up ( with an airspace ).

Are there any alternatives to 705 ?? Something besides owens corning ??
And how much more effective will 705 be than 703 ??? Is it worth it ?
Old 29th June 2006
  #2
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Old 29th June 2006
  #3
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SK1's Avatar
 

Thread Starter
Ethan ?? Please weigh in.

Old 29th June 2006
  #4
Gear addict
 

There's a bunch of competative brands. I used all Knauff and it worked out great. I'm forgetting all the brands (Certainteed, Roxul, others) but in one of Ethan's pieces of Lit he lists a bunch of different brands that work well. I googled, compared specs and prices and went with Knauff 4" 3lb because the local dealer gave me a sweet deal and the specs measured up well. Definitely worth it to shop brands.
Old 29th June 2006
  #5
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norton's Avatar
Dig out your hard copy of the yellow pages... and look for insulation. You should find quite a few industrial suppliers of insulation products... In LA i'd bet there are dozens. I've used both Johns Mannville and Owens Corning.

As far as i can tell the only difference was the price. JM stuff was a few cents a sqare foot cheaper. But not by much.

But the yellow pages or Thomasnet.com the industrial search engine should do the trick.
Old 29th June 2006
  #6
WKG
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Old 29th June 2006
  #7
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I just picked up 20 sheets of CavityRock from Roxul for 96 bucks (Cdn). It doesn't have the absorbtion numbers in the product liturature because it's not being marketed for that, but it is comparable to their RXL-40 board - same size (2' X 4', 2" thick is the stock item) but just slightly denser at 4.5 lbs/ft³. I haven't put the traps together yet so I don't have any before and after numbers, but I'm expecting slightly deeper bass trapping with this stuff.
Old 29th June 2006
  #8
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Thread Starter
Quote:
Originally Posted by WKG
I used Johns Manville 814 2" and it works great. Doubled it up for 4". Specs were comparable, maybe just a hair better than 703.

Here's a great site for comparison on materials.

http://www.bobgolds.com/AbsorptionCoefficients.htm
Great site !

Thanks people !

Old 29th June 2006
  #9
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Glenn Kuras's Avatar
Quote:
Originally Posted by 2leod
I just picked up 20 sheets of CavityRock from Roxul for 96 bucks (Cdn). It doesn't have the absorbtion numbers in the product liturature because it's not being marketed for that, but it is comparable to their RXL-40 board - same size (2' X 4', 2" thick is the stock item) but just slightly denser at 4.5 lbs/ft³. I haven't put the traps together yet so I don't have any before and after numbers, but I'm expecting slightly deeper bass trapping with this stuff.
I am not going to say this stuff will not work but if it does not have test numbers then you really don't know what you are buying.
You may want to stick with either mineral wool or oc products.

Glenn
Old 29th June 2006
  #10
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u b k's Avatar
 

Quote:
Originally Posted by SK1
If you've seen my recent posts, I've been doing a bunch of research on tuning my room correctly. Fabric, materials, placement etc, etc .....

in a heavily misguided and severely pre-coffee attempt to be helpful, i'll clarify that what you're doing is treating your room, not tuning it. tuning a room is a whole different ballgame, a practice rendered relatively pointless for guys in small rooms doing broadband absorption... guys like me and you.

there you have it, my good deed for the day. onwards, and upwards.


gregoire
del
ubk
Old 29th June 2006
  #11
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redrue's Avatar
 

Check out this Auralex mineral fiber... the NRC numbers they
list are better than anything else I've seen. I built bass traps
using the 4" stuff and am VERY pleased with the result.

http://truesoundcontrol.com/products/4MFINS3.html


good luck

Rue
Old 29th June 2006
  #12
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Quote:
Originally Posted by myfipie
I am not going to say this stuff will not work but if it does not have test numbers then you really don't know what you are buying.
You may want to stick with either mineral wool or oc products.

Glenn
That's what it is - mineral wool. It's the same as the RXL-40 board (which has the co-efficients on the tech info page) only it's 4.5 lbs/ft³ rather than the 4 lbs for the RXL-40.
Old 29th June 2006
  #13
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Ethan Winer's Avatar
 

Lightbulb

> Are there any alternatives to 705 ?? Something besides owens corning ??
And how much more effective will 705 be than 703 ??? <

There are lots of materials, but rigid fiberglass and mineral wool are known to work very well. There's also acoustic cotton, but it costs more than rigid fiberglass and is not Class A fire rated as far as I know. As for 705 versus 703, 705 is a little better but it costs twice as much. I did a comparison of exactly what you're asking a while ago, and here's that report:

www.ethanwiner.com/density/density.html

--Ethan
Old 29th June 2006
  #14
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can anyone tell me what alternative for these materials in Germany?
Old 29th June 2006
  #15
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Bob Olhsson's Avatar
 

Check into the densest rigid fiberglass industrial furnace insulation you can find. It used to be much cheaper than anything labeled "acoustical.".
Old 30th June 2006
  #16
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Nutmeg II.'s Avatar
 

Quote:
Originally Posted by lowswing
can anyone tell me what alternative for these materials in Germany?
Carouso ISO Bond (PE fiber with 40kg/qm)
Hanffaser-Dämmwolle (Hemp with 50 to 150kg/qm)
Rockwool.de
...
Old 30th June 2006
  #17
Gear interested
 

Quote:
Originally Posted by Ethan Winer
...There's also acoustic cotton ... is not Class A fire rated as far as I know...

I looked into it. With a flame spread index of 5 and a developed smoke index of 35 (both per ASTM E 84), it really does have excellent fire performance. Too bad they don't have a semi-rigid variety yet.

http://www.bondedlogic.com/technicallibrary.htm
Old 30th June 2006
  #18
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SK1's Avatar
 

Thread Starter
Quote:
Originally Posted by Ethan Winer

I did a comparison of exactly what you're asking a while ago, and here's that report:

www.ethanwiner.com/density/density.html

--Ethan
It's nice to know we have a hard working scientist in our corner ........

Thank you Ethan.

Now if you would come up with some new "designer" fabrics for your traps ......
not just colors, but different types of cool fabric with vibed out patterns.
That would be sweet.

It's all about a cool vibe in the womb.

Respectfully,
SK

Old 30th June 2006
  #19
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Thread Starter
Great insight people !!

Old 30th June 2006
  #20
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lowswing's Avatar
 

Quote:
Originally Posted by Nutmeg II.
Carouso ISO Bond (PE fiber with 40kg/qm)
Hanffaser-Dämmwolle (Hemp with 50 to 150kg/qm)
Rockwool.de
...
thanks!
Old 30th June 2006
  #21
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natpub's Avatar
I do not know your situation, but if you are determined to completely self-build, which we did half of, then we did find the FKR/FSK foil-fronted stiff 705/814 type panels to be more effective on fewer corners than any thinner or less dense material, as Ethan clearly shows. Of course, face only a single panel of the foil out, and rip off the other, since the trapping occurs much behind the panels. It seems to come down, in many ways, to how much space you are willing to sacrifice to segregate off for sonic energy control. At some point, you incur too far into your room, without more superior designs, like the RealTraps.

At many places in the room, you may be better off considering the pre-designed soultions. They may seem expensive at first, but they actually function beyond what several pieces of plain covered stiff rockwool could do. The net savings ends up being better, and the time saved in grief and labour is way more than you might think.

For now, we did finally tame our room with personal effort. But the net cost ended up being more than it would have been to go to the existing professionals such as RealTraps, GIK, and ReadyAcoustics. We did, in fact, package many of our corners in the Ready Acoustics pre-made fabrics, which are excellent. Our home-made Gobos use a felt-type fabric that was cheaper, but is not as effective per measurement.

We are slowly moving into extended rooms of our space, and plan already to seek the aid of those providers, rather then spend our time (figure your own hourly rate, ours is rather high) on self-manufacture. Likewise, if your efforts do not seem to be working, you have someone to turn to, if you spend the extra money to obtain professional products. If you solely rely on your own work, you can only look in the mirror and feel hmm....bummed out.


Cheers.

KT
Old 30th June 2006
  #22
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Lightbulb

SK,

> Now if you would come up with some new "designer" fabrics for your traps ......
not just colors, but different types of cool fabric with vibed out patterns. That would be sweet. <

The fabric we use is custom made for us, having a specific weight and stiffness. We buy huge amounts at a time, and having to stock even four colors is a big deal for a small company like ours. You could certainly wrap our traps with almost any fabric you choose, and the Customers page on our site shows how someone did that. We have also considered offering that as an "up charge" as Glenn does with his GIK stuff but, believe it or not, we haven't really had many requests for that. The bigger obstacle to "trap acceptance" is their large size coupled with the number needed to get excellent results. Now, audio engineers may not care so much, but it's a problem with audiophiles ... at least those who are married. heh

--Ethan
Old 30th June 2006
  #23
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

KT,

> rather then spend our time (figure your own hourly rate, ours is rather high) on self-manufacture. <

No kidding. In my last home studio I hired a carpenter friend to build the low-bass and high-bass type traps shown in my EM article for a smallish room. Even though he was a friend it still cost about $1,500. When I moved to my current home 12 years ago I hired a different pro carpenter friend and that time it cost $4,500! My current room is much larger (34 by 18 feet), but even though I helped him it was still a lot of work and expense.

It amazes me that people will drop $4,000 on some one-trick pony piece of toob gear without blinking an eye, but balk at spending half that to treat their room which makes a profound improvement on every single thing they record and mix.

--Ethan
Old 30th June 2006
  #24
SYL
Gear Head
 

Sorry to intrude, but does anyone know of companys that make stuff similar to 703/705 in Australia?
Old 30th June 2006
  #25
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by Ethan Winer
SK,

> Now if you would come up with some new "designer" fabrics for your traps ......
not just colors, but different types of cool fabric with vibed out patterns. That would be sweet. <

The fabric we use is custom made for us, having a specific weight and stiffness. We buy huge amounts at a time, and having to stock even four colors is a big deal for a small company like ours. You could certainly wrap our traps with almost any fabric you choose, and the Customers page on our site shows how someone did that. We have also considered offering that as an "up charge" as Glenn does with his GIK stuff but, believe it or not, we haven't really had many requests for that. The bigger obstacle to "trap acceptance" is their large size coupled with the number needed to get excellent results. Now, audio engineers may not care so much, but it's a problem with audiophiles ... at least those who are married. heh

--Ethan
You are so right, yes it is cool to have all these colors, but really not to many people want them. Did I not read on the Real Trap site you can paint the fronts of them? I have had a few people do this on our stuff and it does look pretty cool also.

Glenn
Old 30th June 2006
  #26
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

Glenn,

> Did I not read on the Real Trap site you can paint the fronts of them? <

Sure. Our standard traps can be painted with almost anything. But for the HF type you'd want something more like a dye or watercolor, otherwise that might plug up the pores in the fabric.

--Ethan
Old 30th June 2006
  #27
Lives for gear
 

Just for some clarification...

The acoustical cotton is in fact fire rated - and class A at that.

Also, there are 3lb and 6lb densities available in 2'x4' sheets - 1" and 2".

The 3lb cotton is in fact more expensive than the 703 - about double. Now, for that cost, you gain not HAVING to cover it, no itch or hassle installing it, and it comes in your choice of 8 colors. Not for everyone but something to consider when looking at costs.

Lastly, to the original question, if you want to save some $$$, you can do 6" of 703 for 75% of the cost of 4" of 705. It will work just as well if not better due to the additional thickness. Mineral wool will be cheaper than either of those solutions - but harder to work with.

All depends on what you're looking for.

Bryan
Old 7th July 2006
  #28
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Scott R. Foster's Avatar
 

Quote:
Originally Posted by bpape
Just for some clarification...

The acoustical cotton is in fact fire rated - and class A at that.

snip

Lastly, to the original question, if you want to save some $$$, you can do 6" of 703 for 75% of the cost of 4" of 705. It will work just as well if not better due to the additional thickness. Mineral wool will be cheaper than either of those solutions - but harder to work with.

All depends on what you're looking for.

Bryan
Bryan:

I have corrsponded with many who have used the Cotton Batts successfully and who like the material enormously... though I must admit that a good deal of the attrtaction seems to me to be an irrational fear that mineral fiber being an "industrial" material, it must be bad, whereas cotton is "organic".

My $0.02 is that standard MF panels are cheap, effective, and safe - so cotton is just an expensive alternative to me. But, this may be because I don't find MF to be too much of a PITA to work with if you use some common sense [wear the right stuff - invest a couple $ in a a paper coverall and a filter mask - same as if you were going to paint a house using latex paint and a spray gun - get the right gear on for the job and and its all EZBZ]. Others find working with MF to be irksome - so for them I guess the expense has some justification.

Along similar lines of justifying higher cost materials - you mention perhaps needing to use thicker panels of 3 lbs. fiberglass to match the absorption of 6 lbs. fiberglass [703 vs. 705]. I am aware of no published scientific measurements which support this notion. It is a common claim - but unsupported by science AFAIK. Can you provide a link to any such evidence?

In any event, as you point out, one can buy 703 for half the price, so even granting some small superiority to 705 it makes no sense to use it instead simply treating a few more sf of wall or linear feet of corner with 703 - a product costing half as much.

Given that the price and availability of 703 and other 3lbs. fiberglass products and similar rockwool materials varies enormously from city to city and country to country, the best answer is to use Bob Golds excellent compendium of absorption measurements

http://www.bobgolds.com/AbsorptionCoefficients.htm

to shop locally for best value [ignore brand names - simply shop within a chosen class of materials as Doug describes having done above]. This is the smart way to approach the question - pick a material category that fits your needs and comfort level [or categories] and let your wallet guide you to the sorrect solution.

You may find it useful to have a better understanding of how 4" 703 performs in a corner mount. Below is a graph of showing absorption data for 4" - 703 panels in a corner mount we recently measured at Riverbank Acoustical Laborotory. This measurement is plotted along side data on our RT424 - which is the same material inside one of our RT424B Bass Trap Bags.

Note the jump at 100 Hz - this comes from the fabric increasing the entrance impeadance of the panel and elevating the Mass-Spring-Mass resonance [a property which is expressed in all corner absorbers - both panels and wedges - MF and acoustic foam].

I'll be putting the full report up at our website

http://readyacoustics.com

as soon as I get the certified copies back from RAL in PDF form [probably next week]. In the mean time this chart will help you understand what you can expect to achive from 703 in a corner mounting - and the differences that will arise if you upholster the panels with fabirc which has some modest acoustic mass as opposed to leaving them "naked, or using a ultra light / coarse weave fabric].

Note also how the Mid-Band and HF measurements are uneffected by the impeadance jump... interesting stuff.. more later.

Old 7th July 2006
  #29
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by bpape
Just for some clarification...

The acoustical cotton is in fact fire rated - and class A at that.

Also, there are 3lb and 6lb densities available in 2'x4' sheets - 1" and 2".

The 3lb cotton is in fact more expensive than the 703 - about double. Now, for that cost, you gain not HAVING to cover it, no itch or hassle installing it, and it comes in your choice of 8 colors. Not for everyone but something to consider when looking at costs.

Lastly, to the original question, if you want to save some $$$, you can do 6" of 703 for 75% of the cost of 4" of 705. It will work just as well if not better due to the additional thickness. Mineral wool will be cheaper than either of those solutions - but harder to work with.

All depends on what you're looking for.

Bryan
I think just the non itchness would make it worth double the cost. Anyone that has worked with 703 knows what I am talking about.

Glenn
Old 7th July 2006
  #30
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Cojo's Avatar
 

Quote:
Originally Posted by Ethan Winer
I did a comparison of exactly what you're asking a while ago, and here's that report:

www.ethanwiner.com/density/density.html

--Ethan
Hi Ethan!

I was checking out your article (great by the way ) but I can't find any information of what the room was build of. Concrete, dry wall or wood?

Thank you for beeing such a humble and helpful man!

/Cojo
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