Clarification of rockwool properties for Bass Traps and Broadband Absorbers

[Glenn Kuras]

Originally Posted by Hannes_F

Hi Ethan,

the reasons why I keep my results to myself are these:

1. I don't have any business in acoustics.
2. I respect the business in acoustics that people like you, Glenn etc. have.

And let me add that I generally respect very highly what you say about the role of acoustics, double blind testing and all that.

3. My real business is that I am doing string overdubs as a professional service. It may sound bold but it seems I can get results in my studio that currently no one else can, and that has a lot to do with the acoustical design. That is why I am not interested in leaking out too much details about my studio and my recording process.

With other words I am a happy user of acoustical treatment but it is not my mission, that is why I rarely show up here.

Other than that I have had a career in in experimental physics, so I would never do such a statement in public if it were only based on calculations and if I had not tested it in practise.

I have a feeling that it is your room, but also your skill level of recording. Basically it all matters and even if you "leaked" one aspect I am sure it would not lead to someone else duplicating what you are do. With that said I totally respect what you are doing. thumbsup

[DanDan]

captain, that Auralex guy sounds like a Fundamentalist Foamist.
I can imagine that he personally observes a lot of diffusion surrounding him....
No sign of moral fibre.....

If a 4 foot trap is worth it, then a 7 foot trap is 3/7 better and some
The extra size will incorporate a second tricorner at the ceiling. If you have to use four feet only, I suggest 2 x 2 footers in the tricorners would be much more effective than a single panel.

DD

[captain54]

Originally Posted by DanDan

captain, that Auralex guy sounds like a Fundamentalist Foamist.
I can imagine that he personally observes a lot of diffusion surrounding him....
No sign of moral fibre.....

If a 4 foot trap is worth it, then a 7 foot trap is 3/7 better and some
The extra size will incorporate a second tricorner at the ceiling. If you have to use four feet only, I suggest 2 x 2 footers in the tricorners would be much more effective than a single panel.

DD

Dan..

I noticed your "White Room" from your site, and it looks like you have one four footer in one corner from the floor up, and one four footer at the top corner at a right angle...that looks like it could work for me

the Auralex guy did a "room analysis' of my room ("10 x 15", voiceover studio)
and loaded me up with 30 sq ft of foam tiles behind the listening position...interesting though, how his "no treatment below 36" " didn't apply here, whereas his treatment solution there has foam from practically floor to ceiling..

Your White Room has no treatment directly behind the listening position...care to elaborate on your theory behind this setup?

[DanDan]

Cap'n. I review the White Room treatment and perform tests in there periodically. You are referring to an early incarnation, the only one photographed properly. Yes I had a four foot straddling MiniTraps plus that top corner hanging idea. My ceiling height, including a carpet are under 8 feet so I couldn't do floor to ceiling. The current setup has three of the large SuperChunks, 34 inch wide faces. Floor to ceiling.
The area behind me is an exterior wall. It is dry lined ( sheetrock about 2 inches from the bricks. There are two large windows. There is one corner back there with the large SSC. The other 'corner' is an alcove, with four GIK TriTraps, floor to ceiling in both 'corners' of the alcove.
The windows and sheetrock act as bass absorbers back there, to some extent. I didn't treat further because I want the light. There was flutter from the central area between the two windows, but a thin panel on the front wall cured that.
Despite all that treatment back there, there is a bit of bounce knocking around. It is of course way earlier than the desireable 20mS or more. However, even at 10mS or whatever, it is quite welcome in this very dead room. I intend to try some Space Arrays and Space Couplers back there shortly.

DD

[Hannes_F]

Originally Posted by Ethan Winer

Has anyone beside me ever actually tested this?
...

As far as I can tell, the advice to use lower density with thicker panels is based only on anecdotal evidence and Chris Whealy's Porous Absorber Calculator.

--Ethan

________________
The Acoustic Treatment Experts

I have decided to share my data and you can find it here.

[Brainchild]

Booyaka. Thanks, Hannes, you are a true player.

[Ethan Winer]

Originally Posted by Hannes_F

I have decided to share my data and you can find it here.

Excellent, thanks very much Hannes. The only thing missing is a side-by-side comparison of the same treatment done using 705 or some other more-dense material, versus the lower density fiberglass. Again, the question was never whether fluffy fiberglass works well when it's very thick. For me the question was whether lower density is actually better than higher density when the material is very thick. But this is good info too as it is.

--Ethan

________________
The Acoustic Treatment Experts

[mhch]

Originally Posted by Ethan Winer

The only thing missing is a side-by-side comparison of the same treatment done using 705 or some other more-dense material, versus the lower density fiberglass.

How would you perform and measure that comparison ? specially since the difference between fluffy and denser material rather lies in the lower frequencies. What would be the measuring criteria

(FYI, I read your density report)

[Ethan Winer]

If you read my Density Report then you know how to do such a comparison. You have to measure using appropriate software. Start with a bunch of traps made with one material, then measure again with the other material in place, being careful not to move the speaker or microphone. Another method is to bring at least 60 square feet of traps of each type to an acoustics lab. But that's expensive and is not as accurate below 100 Hz. So in this case a home made test is actually better.

--Ethan

________________
The Acoustic Treatment Experts

[Jens Eklund]

Originally Posted by mhch

How would you perform and measure that comparison ? specially since the difference between fluffy and denser material rather lies in the lower frequencies.

http://www.gearslutz.com/board/attac...s-rockwool.gif

[Hannes_F]

Originally Posted by Ethan Winer

Excellent, thanks very much Hannes. The only thing missing is a side-by-side comparison of the same treatment done using 705 or some other more-dense material, versus the lower density fiberglass.

Yep, but I leave that part to others. It is not so difficult actually, just cover a small room with 30 cm (12 inch) of either material and make sure you have full coverage. I am happy with the fact that the lighter material works according to what I thought it should do and go on from there.

Fully covering your walls with 30 to 50 cm light fibreglass is certainly not spouse friendly for a living room or suited for a studio that is also used for storing books, much equipment etc.. While setting this up I was constantly in problems to find new places for things :-). Also you can achieve about the same result with more effort like membrane traps etc. that use up less volume (be aware of the bare wall parts here too, though). However if decided for and done consequently, it works.