Acoustic Hangers construction

[saemola]

Hello all!

With the near completion of my studio construction I'm starting to plan on acoustic treatment.
I've read everything I could find regarding superchunks and acoustic hangers and there are many respectable people (including Mr Sayers himself) who seem to swear by the latter.

I have a 15' 3/4' long, 9' 7/8' wide, 11' 1/8' high control room (hopefully imperial measurements make sense, I use metrics) where I'm planning of stuffing the front tri-corners floor to ceiling with superchunks (2x2').
Loads of 30kg/m3 85mm glass wool which I'm going to use for the work.
I seem to understand that for the back wall (behind the engineer, that is) acoustic hangers can have a deeper, stronger absorption in less space (hence less material). Is this correct?
I can easily fill the whole 9' 7/8' width, go a little deeper than 2' in length and all the way ceiling to bottom with acoustic treatment.

Starting by placing one hanger halfway between walls, measuring the distance between the hanger and the wall and placing another hanger half way and so on... I came up with two scenarios: the first considers 1/4" thick, 2' wide, 8' 7/8' high MDF boards rotated 45° and covered on both sides by 85mm glass wool, whereas the second sketch uses the same setup, but covering the boards only on one side with glass wool, allowing for 13 hangers to fit into the back wall vs the 7 hangers of the first sketch. In the first scenario the space center to center between hangers is 14" 3/4", in the second scenario it is 5" 3/8". In the first case the air gap between hangers is 3" 1/2", in the second it is 1" 5/8".

acoustic hangers 1.jpg

I left two walls out of the sketches to make it easier on the eyes, but it's a perfectly rectangular room.

acoustic hangers 2.jpg

I can make the hangers even taller if necessary, covering filling the whole height between floor and ceiling (leaving the necessary space to make them hang freely).
What are your thoughts on this plan?
It wasn't very easy finding information about the construction of acoustic hangers. Does it sound like I'm doing it right and if so which of the two setups would give the most benefits in your opinion?
Also, do you think this would give more benefits over simply filling the back wall tri-corners with 2' 3/4' x 2' 3/4' superchunks of glass wool and treating first point reflections on the same wall?
Or maybe it would be more beneficial to use superchunks and only place hangers in the remaining space in between the superchunks (which would mean fitting 4 hangers in the first scenario and 9 in the second)?

My initial plan was to completely hide the hangers (hence the back wall) behind acoustically transparent fabric, but then I remembered that a room is supposed to be "infinitely long" by making the back wall "infinitely absorptive." Does it mean I should go the other way around and that a thick, high frequency absorptive curtain would be better fit for covering the back wall compared to acoustically transparent fabric?

One extra, slightly off-topic question: in building my cloud ceiling absorber, would it be more effective to make it larger or deeper? Meaning, assuming I'm covering all the first reflection points coming off the speakers, is it more effective to use a 6' x 4', 170mm thick cloud or would you rather go with a 12' x 8' 85mm thick one? Consider that: 1) I have enough height in my room that I can lower the cloud even as much as 4 feet and 2) I have enough glass wool to make it as thick as I want it to be.

Eager to read your thoughts on this seemingly obscure matter!

P.S. Does it make any difference that my glass wool is covered in kraft paper? I can rip it out if necessary, but I'll happily avoid it if it is irrelevant.
P.P.S. Note that I'm planning this before construction is 100% finished so I don't have REW measurements yet. Once I do I'll make more precise assessments, but I assume this would be a good starting point anyway since a room this small will likely need tons of broadband absorption.

[saemola]

Updated plan.
Wondering if that is the correct way to angle the hangers or if they should rotate 180° on the horizontal axis.

backtraps.jpg

Do you guys think it is ok to stack the superchunks floor to ceiling without breaking them up horizontally with the occasional piece of wood to hold them or does that apply too much pressure and compresses the bottom pieces?

[Eric Best]

Your second plan looks a lot like what I did in my room, and my results were very good What is the wall behind the hangers made of?

[saemola]

Hey Eric,

you mean the "updated plan" in the post right before yours, or the second picture of the first post?
My walls and ceiling are made of 3cm drywall.
Do you think it's necessary to drill into the studs to hang the hangers, or are they light enough that any point into the ceiling would be fine?
I'm also wondering how to drill that hole without trashing my isolation.

Did you find you could just stack layers of wool in the corner with no wood to break them up? If not, how did you go about that?
Thanks for your reply!

[Eric Best]

The updated plan.

The direction of the hangers is not important. Mine are rotated 180 degrees from how you have them, but I don't think that is important. The sound just needs to be routed through them.

For the corner chunks, I just cut triangles and stacked and glued them. Putting a wood layer every once in a while is more for stability if you feel like you need it. It shouldn't affect the sound.

[saemola]

I'll go with the updated plan then.

I read on the forum that there are different opinions regarding them being angled. I have read anywhere from 15°, 45° and now 180°. Some of John's drawings were angled as well. In my case having them angled seems to be ideal for saving space.

I have a few questions if you feel like answering:
1) would you suggest placing glass wool panels in the narrow space between hangers and back wall? I've seen that done in several designs
2) most hangers I've seen seem to be on the small side compared to mine. Mine would be 2,7m tall x 60cm wide, with 1 layer of 8,5cm wool glued to 6mm thick OSB, MDF, plywood or whatever lighter wood I can find. Are they too big? Are they light enough to be hung into the drywall ceiling (they would weigh ~10kg per hanger), or do I need to anchor them to the ceiling studs? I was thinking of simply hand screwing some ring shaped screws into the drywall ceiling and hang some ropes from there to attach to the hangers. Unless you have a better suggestion to avoid trashing my isolation.
3) should I use a thick curtain to cover the hangers or would an acoustically transparent curtain be better for that job?

Edit:
As for the superchunks, I went with using wood shelves in between the glass wool layers as the material was getting overly compressed

Thanks so much for your help Eric.

[Eric Best]

Sorry I didn't see this earlier.

I'll go with the updated plan then.

I read on the forum that there are different opinions regarding them being angled. I have read anywhere from 15°, 45° and now 180°. Some of John's drawings were angled as well. In my case having them angled seems to be ideal for saving space.

I don't think it makes any difference because the waves of the frequencies that we are dealing with are so large that the sound is not directional.

I have a few questions if you feel like answering:
1) would you suggest placing glass wool panels in the narrow space between hangers and back wall? I've seen that done in several designs

I have 4" of rockwool between the back wall and the hangers, and panel absorbers made just from the drywall construction of the back wall.

2) most hangers I've seen seem to be on the small side compared to mine. Mine would be 2,7m tall x 60cm wide, with 1 layer of 8,5cm wool glued to 6mm thick OSB, MDF, plywood or whatever lighter wood I can find. Are they too big? Are they light enough to be hung into the drywall ceiling (they would weigh ~10kg per hanger), or do I need to anchor them to the ceiling studs? I was thinking of simply hand screwing some ring shaped screws into the drywall ceiling and hang some ropes from there to attach to the hangers. Unless you have a better suggestion to avoid trashing my isolation.

I don't know on this one. The more massive they are, the lower frequencies they should absorb, but if you get too massive they will be too low for your goal. I used a low density fiberboard with rockwool attached. My ceiling is two layers of 16mm drywall, so there was plenty of strength to use these. https://www.gamut.com/p/toggle-bolt-anc ... wAodemELig and a couple of lengths of chain to hang them. They arent pretty, but where they are, no one sees them.

3) should I use a thick curtain to cover the hangers or would an acoustically transparent curtain be better for that job?

I just build a frame made of 2 x 4s in front of the hangers and built smaller frames covered with fabric that I used velcro to attach with.

[saemola]

Sorry I didn't see this earlier.

I'll go with the updated plan then.

I read on the forum that there are different opinions regarding them being angled. I have read anywhere from 15°, 45° and now 180°. Some of John's drawings were angled as well. In my case having them angled seems to be ideal for saving space.

I don't think it makes any difference because the waves of the frequencies that we are dealing with are so large that the sound is not directional.

I have a few questions if you feel like answering:
1) would you suggest placing glass wool panels in the narrow space between hangers and back wall? I've seen that done in several designs

I have 4" of rockwool between the back wall and the hangers, and panel absorbers made just from the drywall construction of the back wall.

2) most hangers I've seen seem to be on the small side compared to mine. Mine would be 2,7m tall x 60cm wide, with 1 layer of 8,5cm wool glued to 6mm thick OSB, MDF, plywood or whatever lighter wood I can find. Are they too big? Are they light enough to be hung into the drywall ceiling (they would weigh ~10kg per hanger), or do I need to anchor them to the ceiling studs? I was thinking of simply hand screwing some ring shaped screws into the drywall ceiling and hang some ropes from there to attach to the hangers. Unless you have a better suggestion to avoid trashing my isolation.

I don't know on this one. The more massive they are, the lower frequencies they should absorb, but if you get too massive they will be too low for your goal. I used a low density fiberboard with rockwool attached. My ceiling is two layers of 16mm drywall, so there was plenty of strength to use these. https://www.gamut.com/p/toggle-bolt-anc ... wAodemELig and a couple of lengths of chain to hang them. They arent pretty, but where they are, no one sees them.

3) should I use a thick curtain to cover the hangers or would an acoustically transparent curtain be better for that job?

I just build a frame made of 2 x 4s in front of the hangers and built smaller frames covered with fabric that I used velcro to attach with.

Thanks so much for the reply Eric.
That is the kind of screws I was thinking of using, but they need pre-drilling the ceiling before placing them in and I wonder whether simply filling those wholes with caulk would do the job.
I'll keep researching.

Thanks again!