Superchunk or equal spaced panel bass traps with bales?

[Metrobot]

Hi there
My mixing room is L: 4 W: 2.7 H: 2.6 Meters.
I'm building some large rockwool panel traps 2400 X 900X 200 mm and I thought of staking bales of R30 insulation behind them.
Will this significantly increase absorption? I thought about making superchunks but in Ethan Winer's Acoustic treatment and design for recording studios and listening rooms he states " For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed. For example, if you install fiberglass that is four inches thick with a four-inch gap, higher frequencies whose 1/4 wavelength falls within the four-inch material thickness are absorbed regardless of the gap. And for those frequencies whose 1/4 wavelength is between four and eight inches, the fiberglass is also at the proper distance from the wall or ceiling."

So is there really no need for superchunks
Or would it be better to build some superchunks and space them away from the wall?
On one corner I thought about making a large tri-corner trap so I have some absorption as well as some room for a drum kit.

Cheers and Kind regards
-Matt

[GIK Acoustics]

It is easy to get confused with air gaps when you aren't familiar with how they change absorption.

A full thickness of absorption is always better than an air gap. For example, an 8" absorber is better than a 4" absorber with a 4" air gap. An air gap is just an added bonus that you can do with any panel after it is constructed. So, a superchunk performs better than a panel straddling a corner, and adding fiberglass behind constructed panels will give better results than air (but air is still an added bonus)

I would NOT, however, recommend spacing corner panels from the corner as it seems that part of the reason they work so well for bass absorption is that they are directly in the corner.

To get a grasp of what Ethan is suggesting with the different depths of gap, I think it will make a bit more sense looking at a graph. See the following picture (as a disclaimer, these are calculations and not real world tests or anything)



Looking at the graph, you can determine that the more space you put behind the panel, the better it works for low end absorption. Filling the air cavity with pink fluffy gives an even better result. If you look at the red line (100mm panel with 300mm air gap) you can see that you get slightly worse absorption from 200-500 Hz (this is the "hole" Ethan is referring to when you increase the air gap to larger than the absorber) but you get better absorption in the low end. This trade-off is usually a no brainer for most situations, as the difference isn't huge from 200-500 Hz, but certainly is in the low end (but a lot of times, such a large air gap isn't possible)

Hope all that makes sense. Let me know if you have any specific questions with this explanation.

[Metrobot]

Cheers Alex
That's just the kind of answer I'm looking for.
One more question if you please.
Where is the best place to put membrane traps?
I'm already planning to fill the corners and i'm assuming that putting them behind panel traps would render them pointless.
Cheers
-Matt

[thefruitfarmer]

I'm building some large rockwool panel traps 2400 X 900X 200 mm

How heavy will they be?

Just a thought, it may be easier to build, shift and fit several smaller ones.

Superchunks are more effective than framed slabs across the corner and are easier to build. However, if you frame the individual slabs then it is easy to move them when you move house. They are slightly less effective but you can use more of them and, if necessary you could put some more RW behind them too....

[Metrobot]

they'll have some weight to them but as long as they fit through the door they should be good. I was planning on making a wood frame with some handles on them so they can be moved easily. each superchunk will be 1.2m so they can be stacked.
-Cheers

[GIK Acoustics]

Cheers Alex
That's just the kind of answer I'm looking for.
One more question if you please.
Where is the best place to put membrane traps?
I'm already planning to fill the corners and i'm assuming that putting them behind panel traps would render them pointless.
Cheers
-Matt

It depends. But to be a bit generalist, bass notes travel along walls, so you usually want them against a wall. A corner works well too, but not straddling the corner like you would normal traps. Actually against both boundaries would be best (unless you design them for use in the corners like that purposely).

[Metrobot]

Thanks. Advice greatly appreciated.
-Cheers