Will this rockwool work for me?

[Jens Eklund]

Originally Posted by DanDan

I have done Jens. Tried Wes Lachot and Jeff Hedback's websites. Newell's, Northward. I see slats, more often diffusive than LF tuning. I see lots of Invisible Alpha.

The only decent example of a single successful perf design came from you Jens.
To my knowledge there has not been a second example presented.

You have said before, 'look at any studio on the cover of Mix magazine'.
Actually I did. Nada.

The promotion of a singular technique or aspect of the overall picture seems to me unbalanced. There is little point in encouraging DIY of tuned pressure traps when the readers are often in temporary/rented/small/amateur or prosumer spaces. At least four GS who tried, failed.

While I study and admire the effort, the science, the intelligence, in pro designs, I have worked in quite a few. Far too many don't work well in terms of translation, because the designer didn't have the big picture.
e.g. Flat is not the goal. Nor is a perfect RFZ gap. All of the compromises have to be in harmony for these places to actually deliver. What I have experienced suggests a dearth of actual listening, tuning by ear and experience, focussed on results, i.e. translation,.

DD

So you are seriously doubting the usefulness of perforated panels? Are you serious?

Slotted panels are just one type of perforation, the principle is the same. You really need to pick up a copy of Acoustic Absorbers and Diffusers (or any other reference on the topic).

[Jens Eklund]

Originally Posted by DanDan

Jens has suggested that the OP consider lighter materials, saggy and difficult to create clouds with. Also tuned pressure traps.
Not an answer, and not helpful.

80KG is just fine.

DD

Let the OP decide if my answers are helpful or not!

[midoban]

come on guys.. i think everyone here helped me a lot as i didn't know very much about any of these stuff when i started the thread. i still know just a little but enough to get a plan going.

one important thing i understood is that low density materials are good but only if you have the privilege to build very thick traps, which i don't have because my room is just 3x3.5 meters and i wanna start simple.

also, from the tests Glenn posted i realized that on corner traps, the high density materials work better (again, under 6").

i still dont know much about airgap/no airgap on side walls traps, but everywhere i look, i see people leaving a gap, so i think i'll do it too.

so for now, my simple plan is: 80kg/m3 4" thick rockwool straddled on all corners and 45-60kg/m3 (whatever i find) 2"-3" thick on the side walls with a 2"-3" inch gap from the wall.

[Jens Eklund]

btw:

http://www.gearslutz.com/board/6507362-post2.html

!


Last entry for me since my posts aren’t "helpful" apparently ...

[petertjed]

Glenn,

Can you tell more about your test with square traps in this thread?

why are superchunks triangal shaped? and not quadrangle..

thanks,

peter

[Glenn Kuras]

Originally Posted by midoban

come on guys.. i think everyone here helped me a lot as i didn't know very much about any of these stuff when i started the thread. i still know just a little but enough to get a plan going.

one important thing i understood is that low density materials are good but only if you have the privilege to build very thick traps, which i don't have because my room is just 3x3.5 meters and i wanna start simple.

also, from the tests Glenn posted i realized that on corner traps, the high density materials work better (again, under 6").

i still dont know much about airgap/no airgap on side walls traps, but everywhere i look, i see people leaving a gap, so i think i'll do it too.

so for now, my simple plan is: 80kg/m3 3" thick rockwool straddled on all corners and 45-60kg/m3 (whatever i find) 2"-3" thick on the side walls with a 2"-3" inch gap from the wall.

Make the panels straddling no less then 4".

[midoban]

Originally Posted by Glenn Kuras

Make the panels straddling no less then 4".

ok thanks i'll make it 4".

[DanDan]

midoban, unfortunately as an identified professional, I cannot let suggestions that I am merely guessing, go unchallenged.
As I said a search will show pattern here.

See http://www.bobgolds.com/AbsorptionCoefficients.htm
Same materials are tested with airgap and without. The advantage, almost a free lunch, is clear.
If you want to get deep into this see the thread Q4Avare.

I notice no mention of a Cloud in this last post. The cloud is just as important as the side reflection control. You will have difficulty using lighter saggy material for this job.

Ethan's test shows the denser material to be more effective all over the room, in terms of the LF.

So I again recommend 80KG.
I, and many others recommend 100mm plus 100mm gap (4 inch) for the Cloud and side reflection controllers.
Straddling panels at least the same thicker is better.
FRK can enhance the LF performance of all of them, but I wouldn't bother unless you can buy the panels with FRK already on them.
This is often an option.

The mesh used to cover the gaps between plasterboards is excellent for holding saggy fibre, or even more rigid fibre which might eventually sag, in place.

You should be able to see it in this picture here.
http://www.gearslutz.com/board/6227236-post24.html

I have found it best to include a layer of polyester batting under the final fabric, particularly in overhead traps. This evens out bumps, helps hide the dark insulation, prevents fibres from raining down during a heavy bass session.....

Good luck with your build. You will be delighted with the sonic rewards.

DD

[midoban]

Originally Posted by DanDan

midoban, unfortunately as an identified professional, I cannot let suggestions that I am merely guessing, go unchallenged.
As I said a search will show pattern here.

See http://www.bobgolds.com/AbsorptionCoefficients.htm
Same materials are tested with airgap and without. The advantage, almost a free lunch, is clear.
If you want to get deep into this see the thread Q4Avare.

I notice no mention of a Cloud in this last post. The cloud is just as important as the side reflection control. You will have difficulty using lighter saggy material for this job.

Ethan's test shows the denser material to be more effective all over the room, in terms of the LF.

So I again recommend 80KG.
I, and many others recommend 100mm plus 100mm gap (4 inch) for the Cloud and side reflection controllers.
Straddling panels at least the same thicker is better.
FRK can enhance the LF performance of all of them, but I wouldn't bother unless you can buy the panels with FRK already on them.
This is often an option.

The mesh used to cover the gaps between plasterboards is excellent for holding saggy fibre, or even more rigid fibre which might eventually sag, in place.

You should be able to see it in this picture here.
http://www.gearslutz.com/board/6227236-post24.html

I have found it best to include a layer of polyester batting under the final fabric, particularly in overhead traps. This evens out bumps, helps hide the dark insulation, prevents fibres from raining down during a heavy bass session.....

Good luck with your build. You will be delighted with the sonic rewards.

DD

Thanks for this info.. so you suggest everything to be 4" - both corners and side walls traps, and also 4" air gap on side walls. i can see that the 4" performed better on these tests, so yeh, i'll do it.

[DanDan]

Given the work involved in sourcing the fibre, the fabric, constructing frames, hanging them, I think anything less than 4 inch is a wasted opportunity.
So yes minimum 4+4 airgap for the cloud and sides. At least 4 in the corners. 6 is of course better or even 8 if Glenn's testing says 80KG and 8 inches is still all good.
Try to do the four vertical corners first, all the way, floor to ceiling.
DD

[SCDBM]

What I did was making a sandwich of both the fluffy panels and the dense panels.

Chunks are 60cm * 60cm * 1m, both ourside panels are the dense ones with the fluffy 201's inbetween. Works like a charm, also made thinner 20cm traps the same way (so 5cm dense, 10cm fluf, 5cm dense again)

in this way i was able to address a very nasty cancellation between 100<200hz, just experience, you'll hear it soon enough once it comes together.

[PaulRain]

if you compare the same material, at certain thicknesses a higher density could be more efficient at very low frequencies but not so much.....then the theory of filling up the room with (as many as possible) bass traps like that will be effective very low.
see the two images, compared materials are Rockwool 45 and 85 kg/m3
more or less because the variables are so many and from brand to brand the specs could be different.
100mm with no air gap the denser panel is a little bit more effective under 150Hz
but way less between 150 and 1000.
200mm less dense is better....
with air gap less dense is better at both these thicknesses...
these datas comes from the free Porous absorber Calculator.....but......using a different and more refined calculator I get slighly different result....the variables are really many and the confusion grows every day...

[midoban]

Originally Posted by PaulRain

if you compare the same material, at certain thicknesses a higher density could be more efficient at very low frequencies but not so much.....then the theory of filling up the room with (as many as possible) bass traps like that will be effective very low.
see the two images, compared materials are Rockwool 45 and 85 kg/m3
more or less because the variables are so many and from brand to brand the specs could be different.
100mm with no air gap the denser panel is a little bit more effective under 150Hz
but way less between 150 and 1000.
200mm less dense is better....
with air gap less dense is better at both these thicknesses...
these datas comes from the free Porous absorber Calculator.....but......using a different and more refined calculator I get slighly different result....the variables are really many and the confusion grows every day...

Actually, i think i noticed that even on DanDan's tests link. on 4", the fiberglass 701 was overall better then the 705 on all frequencies, both with gap and with no gap, here:

[DanDan]

Calculators give differing results. They don't include the drum head effect. The tests in reverb chambers hardly apply to small rooms with lots of normal incidence. Choosing the optimum material seems to be a minefield.

However, when you get on the phone you typically find only two materials nearby.
Rolls of light fluffy stuff for the Attic or in between studs.
Light floppy batts for, well the same thing.....

There is no market for the rigid stuff which would make DIY so much easier.

Everest has a graph showing the following in the MHOA book.
The overall performance of fibre is generally very very similar from 1.5 pcf to 6 pcf. A range of 1:4.

So why sweat it? Go with light fluffy for deep traps. Go with the saggy batts, frame and mesh them. The tests show similar performance. Predictions show better. They are much cheaper.
It will all work well.

DD

[psykostx]

Rockwool is incredible stuff... Roxul AFB is all I use. It's very versatile, but it's OH SO ITCHY so wear gloves and a mask.