Acoustics for Small Band-Studio Project (incl. measurements)

How to use REW, What is a Bass Trap, a diffuser, the speed of sound, etc.

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FreakyAlleyCat
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Acoustics for Small Band-Studio Project (incl. measurements)

Post by FreakyAlleyCat »

Hi everyone,

I just registered here after i got the recommendation to consult you guys with some of the questions i currently have in a couple of local german recording forums.
After reading all of the instructions, i decided it might be necessary to open up a new topic, so here goes:


1. What's this about?

Me and my band had the opportunity to move our rehearsal space to an old US-Army facility in Mainz/Germany that is right now being converted to completely serve as practice space for bands and musicians. Neighbours and soundproofing is absolutely not an issue, which is great because we're a four piece hardrock/stoner rock combo with a drummer that likes hitting hard, a deep love for tube amps and a despise for everything in-ear. :mrgreen:

All of the walls and ceilings are solid concrete. Additionally the concrete ceiling has a suspended ceiling made of plasterboard like you'd find in an office space.

Whats exceptionally great about the space is that we can now call an entire four-room officers-appartement within the facility our own, which led to the idea of building a small studio with a live/practice room, a controll room and a storage room (a fourth room is rented out to a drummer buddy of ours to make the overall costs work out).

I've spent the last couple of months not only renovating but also reading on acoustics, building huge cornertraps and absorbtion panels and measuring our progress using REW. But now i've come to a point where i really can't figure out the next steps on my own, hence this topic.

This is not meant to become a professional recording studio. The rooms are way too small for that and being mostly young and just off from university, we're all somewhat of on a budget (but since this is an ongoing project and we split it by the four of us, we can definitely manage to put in a couple of hundret Bucks). What this is meant to become is our own little rock'n'roll recording paradise within the limits we can reach. We're well aware, that the rooms aren't optimal - but since we've had great sucess recording our music DIY in a far worse environment, we'd like to step up our game and just make it the best we can for now.


2. Overwiew

This is the overall layout:
bild_von_ios.png
Room No. 2 is our live/practice room
Room No. 3 is our storage room (which we couldn't really use as anything else since theres a huge AC unit controll panel for the entire building fixed to the wall)
Room No. 4 is our controll room
Room No. 5 is rented out to our drummer buddy to make the overall rent we're paying work out


Here's a nice little render our drummer generated to give you a little bit of a feel for the layout:
2020-03-29_headquarter_v01.png

The floor used to be some ugly sort of vinyl floor that we changed out for a more sturdy and nice looking thick laminate:
signal-2020-05-09-231512_copy.jpg

Since we're mainly focusing on the live room right now (controll room might come later), here's the measurements of lenght and width of the live room.
The room is 240 cm high floor to suspended ceiling and roughly 260 cm high floor to concrete ceiling. I hope it's okay to use Meters and Centimeters since we europeans have little to no clue about imperial or US customary units.
bild_von_ios.jpg
("Fenster" is german for "window")


3. What we've done so far

The first thing we've done is simply build the biggest corner traps we could fit, using rockwool sonorock. Unfortunately there's only two corners usable for huge triangle traps. The third corner is blocked by the entrance door and the fourth corner is a little hallway.

Here's the corner traps built into the first two corners:
20200521_000234.jpg
IMG-20200522-WA0009_copy.jpg
signal-2020-05-25-220256_copy.jpg

In the third corner just behind the main entrance door i've basically just tried to fit as much rockwool as i could:


20200603_212644.jpg
20200603_212713_HDR.jpg
Here you can see the little hallway in the fourth corner of the room (just behind the drumset):
IMG-20200520-WA0020_copy.jpg


Next we've build some absorption panels out of rockwool, just trying to treat some of the first reflection points and placing them just by ear (that was basically done so we could start rehearsing again but the results were already huge so the've just stayed where they are until today). We've also hung up a thick acoustic curtain to treat the window.
20200724_212717.jpg
20200724_212808.jpg
20200724_212816.jpg
Since we couldn't fit a corner trap in the hallway - these are basically just extra thick rockwool panels.
20200724_212754.jpg
And also one just behind the guitar cab that i had left over and worked wonders in rehearsal.
(old bass cab beneath the marshall cab is just abused as a riser)
20200724_213632.jpg
The long black wall is still completely untreated because I wasn't really sure wether to just "plaster" the place with absorption panels or introduce some sort of diffusion instead. This will be part of my questions at the end of this post.


So this is the current situation. I wasn't really sure how to best go on from here so what i did was measure the room just as it is right now for you to see what's going on.

Since i've just run out of attachement space, the measurements will be up next in a separate post.
Last edited by FreakyAlleyCat on Thu Sep 17, 2020 7:53 am, edited 6 times in total.
FreakyAlleyCat
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

4. Measurements

Since there's more than one sound source in a live room and i couldn't really find any useful information on the internet on how to place speakers and measurung microphone in a situation like this, i've done a couple of measurements using different spots.

Here's the first one, right at the drum position:
Drum Position (1).jpg
Drum Position.jpg
Drum Position Bassbereich.jpg

Here's the amp position:
Amp Position.jpg
Amp Position (1).jpg
Amp Position Bassbereich.jpg

Here's one across the room:
Amps in Flur.jpg
Quer durch den Raum - Amps in Flur.jpg
Quer durch den Raum - Amps in Flur - Bassbereich.jpg

Here's the other way across the room:
Drums zu Tür.jpg
Quer durch den Raum - Drums zu Tür.jpg
Quer durch den Raum - Drums zu Tür - Bassbereich.jpg

5. Questions

So here's my question:
Where would you go from here?

I realize that bass is still a bit of a problem but since we're running out of corners i guess there's not a whole lot we can do about that. One of my ideas was to put an entire ring of rockwool within the suspended ceiling and just around the entire ceiling but i wanted to check with you guys before buying those crazy amounts of rockwool.

The large black wall and the space on top behind the guitar amp are still untreated. Should I go on building rockwool panels to simply plaster up all of the walls or would you recommend something else? I'm a little afraid of overdampening my high frequencies.

What about diffusion? Should we maybe just build large 1D Diffusors and put them up across the long black wall? Or anywhere else?

Any hints or tips on what's the next right step would be really appreciated.
The room already sounds much better than what we could have hoped for within our opportunities as a small rock band in small rehearsal spaces. So we'd love to kinda max out what the room can do.

Thank you very much and greetings from germany!
Lukas
Last edited by FreakyAlleyCat on Thu Sep 17, 2020 7:55 am, edited 1 time in total.
DanDan
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by DanDan »

Hi Lukas. The floor and the ceiling are the two biggest areas, and they are parallel. Oh Oh. Can you identify what type of tiles are in your suspended ceiling. If they are not fully absorbent, I would replace them with Polyester e.g. Caruso Isobond or Autex. Be careful though. Many 'office' tiles have a blocking layer.
It would also IMO be worth adding a layer of light cheap attic insulation, Knauf Ecose etc. above the new tiles.
FreakyAlleyCat
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

DanDan wrote:Hi Lukas. The floor and the ceiling are the two biggest areas, and they are parallel. Oh Oh. Can you identify what type of tiles are in your suspended ceiling. If they are not fully absorbent, I would replace them with Polyester e.g. Caruso Isobond or Autex. Be careful though. Many 'office' tiles have a blocking layer.
It would also IMO be worth adding a layer of light cheap attic insulation, Knauf Ecose etc. above the new tiles.
Hi Dan,

thank you very much for the quick reply and for your input.
Now that you put it that way... yes, the floor and ceiling are huge parallel surfaces. Funny how I read for hours and hours on the topic and noone ever pointed it out as straight forward as you just did. Definitely gave me a "dang... right" moment here. :oops:

The tiles are simple plasterboard, roughly 1,5 cm thick, very very light and just loosely layed down on an alumium frame construction. I feel like they help reducing the overall echo of the room by a great deal but will most definitely not be fully absorbant. There's no blocking layer or anything like that, just 20 cm of air up to the concrete ceiling.

Since replacing every single tile with Isobond or Autex is going to cost us quite a bit, I guess it would be worth trying to fill up the entire space above the tiles with sonorock (which is rockwool just as the Knauf Ecose) first? From what i've read the plasterboard should pretty much just let through the bass and low mid frequencies so it might be worth the shot before going full berserk on our bank accounts? Also from what i've read the overall ceiling construction should already help with the bass a little because it starts swinging, somewhat similar to a helmholtz resonator.

So next step: Ceiling. :thu:


EDIT: I just did the math. To replace every ceiling tile with Isobond WLG 040, 10cm thick would cost us roughly 800 €.
Filling the entire air gap under the plasterboard with rockwool sonorock would cost us about 240 €. So yeah, I guess we're going to try that first. If we come to the conclusion that the plasterboard itself reflects too much and won't let the critical frequencies pass through we can still remove the plasterboard and just put some kind of fabric under the rockwool to make it look ok.

I hope i'm not completely off the track here.
DanDan
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by DanDan »

Many of those 'crunchy' ceiling tiles are quite reflective. The elephant in the room would be flutter echo between ceiling and floor.
A 20 cm fibre trap up there would be brilliant. BUT suspending it on fabric is not easy. Fireproof fabric is not cheap and you would probably also need some sort of mesh frame. A classic suspended ceiling would have say 30mm tiles and a 40cm drop. They are very absorbent down to 50Hz.
I doubt if your CIB040 is rigid enough at 30mm to support itself and the weight of fibre above. 035 probably. The guys at Don Audio are super helpful.
Autex do a 30mm which is rigid enough and has a tougher cosmetic layer.
If you go for 100mm CIB check the weight! But at that depth I don't see a need for the light fibre over it.
You could economise by starting with say half the tiles. Do the areas over drum kits, singers, etc.
FreakyAlleyCat
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

DanDan wrote:Many of those 'crunchy' ceiling tiles are quite reflective. The elephant in the room would be flutter echo between ceiling and floor.
A 20 cm fibre trap up there would be brilliant. BUT suspending it on fabric is not easy. Fireproof fabric is not cheap and you would probably also need some sort of mesh frame. A classic suspended ceiling would have say 30mm tiles and a 40cm drop. They are very absorbent down to 50Hz.
I doubt if your CIB040 is rigid enough at 30mm to support itself and the weight of fibre above. 035 probably. The guys at Don Audio are super helpful.
Autex do a 30mm which is rigid enough and has a tougher cosmetic layer.
If you go for 100mm CIB check the weight! But at that depth I don't see a need for the light fibre over it.
You could economise by starting with say half the tiles. Do the areas over drum kits, singers, etc.
Hi Dan, thanks again for your help.

I think what we're going to do is start replacing the tiles above the drums and amps (singer position is not as important since he won't be performing his final takes with the rest of the band when recording, so vocals are done either later on in the process in the best sounding spot or parallel in a different room).

So your recommendation would be Iso bond WLG 035?? I'm actually not too worried about the isobond supporting the weight of itself and an additional layer of 20cm rockwool because due to the aluminium frame construction the weight of the rockwool will be spread to multiple tiles and will also rest mainly on the aluminium frames as long as the isobond stays within the 20mm range. From my understanding the isobond is mainly necessary because it's more permeable and less reflective for the frequencies to really be able to enter the rockwool layer, so it shouldn't make a huge difference whether we chose 20mm or 30mm isobond, right?
DanDan
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by DanDan »

I have a sample tile here from Autex. 30mm, stiff enough not to worry about a layer of fibre over it. It does have a cosmetic sort of fabric or felt layer. I have never seen Isobond! Or felt it. I suspect that 040 which is 10KG per cubic metre is probably a bit floppy. I did ask a supplier about 035, my interest was finished 100mm traps, no fabric, no extra work.
Hi Dan,

yes, ISO-Bond WLG 035 is very stiff and can be hanged down with just four chords or by gluing it onto the ceiling with a SilkaBond T2 or any elastic glue past. You can also put it into dry construction frames and leave it open. It does not dust and it keeps the white color. It does not smell and it´s 100% economic and human being friendly polyester material. It´s very good to cut with an electric knife, so you can cut, glue or hang it down to cover the complete ceiling.

Shipping is 48€ for each package of 6 pieces.
Bulk Shippment in 1,2m x 0,6m x 0,6m packages.

To hang them from the ceiling, which would improve the deep frequency absorption, I would recommend to use thin Nylon strips and
Put then trough the isobond panels with a needle. We have hooks here in a local superstore if you should have problems to source them I can include them for some €. They are not so expensive here. Between 20-40 cents I think
I can also look for a nylon strip if you wish.

Best

Aaron
FreakyAlleyCat
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

Thank you Dan, that is really really helpful!

I'm going to look into IsoBond and will report back here when there's anything new to report (might take a little while since we're busy working on new songs instead of working on the room for a change).

Cheers,
Lukas
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

As I mentioned in the original post, one of our aspects is to keep the costs down that we can keep down without screwing things up too much. So here's a thought that just came into my mind:

The reason we're looking into acoustic foam ceiling tiles like Isobond is mainly because the cardboard tiles might be too reflective and prevent frequencies from entering the layer of absorbtion we're planning on installing above the suspended ceiling anyway, right?

So why not just make ceiling tiles out of rockwool and nicely wrap those in fabric?
I just did a test piece and the 100mm rockwool is well able to support it's own weight and an additional layer of rockwool on top of it, so we'd end up with 20 to 30cm of rockwool on the entire ceiling surface. This could actually save us a LOT of dough.

Is there anything i'm missing?

Simply replacing all the tiles with 100mm Isobond is not an option because unfortunately it looks like that's well above what we can afford right now.
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by DanDan »

You can certainly use dense semi rigid rock or glass fibre as ceiling tiles. Realtraps sell 100KG glass fibre with a sort of felt facing built in. No wrapping needed.
Since you plan to put a light density fill above the tiles, why not use much thinner cheaper ones? I have an Autex Ceiling tile here, 30mm, certainly rigid enough to hold a layer of fluffy fibre above it. It has a reinforced sort of felt face built in.
FreakyAlleyCat
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Re: Acoustics for Small Band-Studio Project (incl. measureme

Post by FreakyAlleyCat »

Well, that's basically because every single solution i've found so far is a lot more expensive compared to the rockwool.
Plus most of the suggested brands are kind of hard to find here in germany (or cost an additional fortune in shipping).

In a german acoustics forum i've seen a professional studio builder measure all sorts of different fibres and he basically came to the conclusion that a thick layer of lower flow resistance materials (like rockwool sonorock) doesn't really differ much from a thinner layer of higher density material with a higher flow resistance in the overall absorbtion effectiveness. So since we've easily got the space above our suspended ceiling, doing the entire thing in sonorock seems like the best bang-for-the-buck solution to me right now.
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