Type of Rockwool for home made absorbers?

[schismatic]

Rockwool's website provides data sheets with sound absorption co-efficients which give an idea of the relative merits of different densities and thicknesses.

I've jut built some myself and on the basis of the data sheets, I chose 100mm thick slabs of RW3 which is 60kg/m3 and provides very good all-round broadband performance.

I would think that 3cm is much too thin unless you hope to hang with a substantial air gap behind them. Roughly 4 inches minimum has been given as a rule of the previously.

[Sugarman]

Originally Posted by schismatic

Rockwool's website provides data sheets with sound absorption co-efficients which give an idea of the relative merits of different densities and thicknesses.

I've jut built some myself and on the basis of the data sheets, I chose 100mm thick slabs of RW3 which is 60kg/m3 and provides very good all-round broadband performance.

I would think that 3cm is much too thin unless you hope to hang with a substantial air gap behind them. Roughly 4 inches minimum has been given as a rule of the previously.

Thanks for your reply.
The Rockwool types I was referring to are 70kg/m3 vs 135kg/m3.
I was under the impression that thickness doesn't matter that much when you just wanna dampen the reverb of the room. I know that if you wanna make a professionally treated room and you wanna tame the bass freqs as well, then you need much thicker absorbers.
But for reverb only, 3 cm is too thin? I mean, a 0,5 cm thin carpet can do wonders on reverb time, so I figured 3 cm would be plenty.

Would you go for the 135kg/m3 option then? or would the surface be too hard?

Thank you

[schismatic]

I'm not sure whether the heavier stuff may actually be more reflective - try to get some decent data from the manufacturers.

Out of interest, is there a particular reason why you wouldn't want to treat the room fully, as opposed to your 'dampen reverb' approach using thin materials?

Surely if it is your studio, then some decent, effective broadband treatment will do wonders not only for reverb etc, but also help significantly in terms of frequency response, stereo imaging, and therefore better mixing?

Thinner materials will give you less overall benefit within your studio space.

[Sugarman]

Originally Posted by schismatic

I'm not sure whether the heavier stuff may actually be more reflective - try to get some decent data from the manufacturers.

Out of interest, is there a particular reason why you wouldn't want to treat the room fully, as opposed to your 'dampen reverb' approach using thin materials?

Surely if it is your studio, then some decent, effective broadband treatment will do wonders not only for reverb etc, but also help significantly in terms of frequency response, stereo imaging, and therefore better mixing?

Thinner materials will give you less overall benefit within your studio space.

The reason why I want to keep the absorbers as thin as possible is because of space and also for aesthetic reasons, though I know that aesthetics should NOT be a concern here on GS But I must admit it matters to me. My room is only 40m2. If I hang 4 inch absorbers on all walls, my room would feel significantly smaller, more crowded/cramped... That is my concern.
The main reason for dampening my room in the first place is because I record vocals in there, and using a U67 or any other condenser mic on loud vocals in a lively room sounds really bad once you get the compression going. So I want to get rid of reverb, and I thought that 3cm thick absorbers on all walls would do the trick.
Would 10cm (4 inch) absorbers really absorb more low mid/bass freqs? Not that it's a great need to me (I haven't noticed an issue in my room with low freqs), but if there really is a massive difference I would definitely consider the thicker absorbers, as you say

[Jens Eklund]

Originally Posted by Sugarman

I am about to build my own absorbers for my studio.
I will use 3 cm (1.2 inch) thick Rockwool, put it into a wooden frame and finally cover it with fabric. I know it's on the thin side, but I mainly need to dampen the treble and high mids here, and I would like the panels to look as discrete as possible.

My question is, should I go for the heaviest Rockwool possible, or should I rather pick the softer and lighter version..? Both versions are stiff and easy to cut and arrange (not like the standard fluffy Rockwool), but one is almost twice as heavy as the other, making the surface harder because the material has been squeezed much tighter, I suppose.
Since I need internal reverb dampening and NOT wall isolation towards neighbors, I suppose I should get the lighter material, which has a softer and more absorbing surface?
Or am I wrong?

Sticky with links?

4m x 5m x 2.5m room - modal resonance problem

Bass Trap wool

[Sugarman]

Originally Posted by Jens Eklund

Sticky with links?

4m x 5m x 2.5m room - modal resonance problem

Bass Trap wool

I don't get you point Jens?

[Jens Eklund]

Originally Posted by Sugarman

I don't get you point Jens?

Do you really need to absorb only treble? Have you made any measurements confirming this? Normally we work hard to keep the HF range (but naturally in a controlled manner) in studios while absorbing massively in the lows (below about Schroeder frequency = the modal range), but exceptions might naturally exist depending on the given situation (always measure first i o w). Even if you only need to absorb HF; read up on flow resistivity in order to maximize the performance of your panels depending on thickness. If nothing else, you´ll learn something.

[Sugarman]

Originally Posted by Jens Eklund

Do you really need to absorb only treble? Have you made any measurements confirming this? Normally we work hard to keep the HF range (but naturally in a controlled manner) in studios while absorbing massively in the lows (below about Schroeder frequency = the modal range), but exceptions might naturally exist depending on the given situation (always measure first i o w). Even if you only need to absorb HF; read up on flow resistivity in order to maximize the performance of your panels depending on thickness. If nothing else, you´ll learn something.

I'm a songwriter/producer, so I don't know much about this field, as you can probably tell ; ) I just wish to simply kill the audible reverb in my studio, which I thought would be in the high mid and treble area. You know, you shout a short word and there's this annoying tail ringing - a reverb.... Useless for vocal recordings! There might ALSO be issues in the lower frequencies, but to fully sort that issue I would need to hire a professional acoustician to do analytical measuring and to help me build the right absorbers etc etc.... This is a completely different (and much more expensive) project.
For now, I just wanna get rid of that obvious reverb tail. Maybe it's more in the high mids than in the treble register.. don't know. My walls are made of really hard fiber gypsum, my floor is made of beautiful oregon pine wood which I don't wanna cover with carpets, so to me, the most logical solution is to hang absorbers on the hard walls, and I was assuming that it wouldn't make any real difference whether I use 2 or 4 inch thick rockwool in order to kill reverb tails. Right?

[Jens Eklund]

Ok, I understand. I´m going to do something I normally never do (give advice without measurements dictating what´s required):

Make you panels as deep as you can (I would never design anything shallower than 4”), and use wool with a flow resistivity of about 10-20 kPa*s/m² if 4” or less (5-10 kPa if deeper). Experiment with position and try and cover areas that are responsible for early reflections or flutter echo. If your room is big, you might want to look into diffusers.

[hsal]

+1 to the above, if you make them 12 cm or more, "rockwool flexibatt" is a good and cheap choice that is easy to get in scandinavia (around 8 kPa*s/m²).

[Jens Eklund]

Originally Posted by hsal

+1 to the above, if you make them 12 cm or more, "rockwool flexibatt" is a good and cheap choice that is easy to get in scandinavia (around 8 kPa*s/m²).

+1

If not deeper panels than about 150-180 mm, Flexibatt (8,8 kPa) is a good choice. If deeper; Isover Piano (6 kPa) is a good option.

[DanDan]

Measurements are ideal but one can get a good sense of tonal balance in other ways. Handclaps reveal flutter and slaps or show up a nice HF reverb tail.
Low frequency can be stimulated by vocal bursts of tone.
A plosive consonant followed by a broad vowel is idea.
Buh. Da, etc. etc. The pitch can be easily varied while walking about. One can make alcoves and such ring like bells.

It would be worth checking out the low vocal resonances of this room in such a simple manner or even better by measurement.

Some small rooms have plasterboard walls and ceiling, so intrinsically have some LF absorption. However the smaller ones can easily have nasty resonance at the bottom of the vocal or acoustic guitar range. 70-100Hz.
Luckily simple corner traps seem to peak in this range also.

Standing singers mouths and the mic can be very close to the ceiling.
So a cloud would be a priority.

For vocals, in small room....
A layer of 50mm 100KG fibre in a frame on the walls. 100mm sure, if have the space. But this is only flutter control. I would recommend focus on Corners, corners, corners.
And a Big cloud, with an airgap.


DD

[hsal]

+1

If not deeper panels than about 150-180 mm, Flexibatt (8,8 kPa) is a good choice. If deeper; Isover Piano (6 kPa) is a good option.

Yes over certain thickness lower resistivity is better (also for the wallet).