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Production studio acoustics first aid

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Production studio acoustics first aid

Postby erkperk » Thu Jul 16, 2020 8:44 pm

Finally I'm getting a go at improving the acoustics of my music production space. I am a newbie at studio acoustics, which is why I am asking for feedback/advice in this forum before I go ahead. As described below my approach is a bit improvised with the aestetics in mind. Any advice is very welcome.


What I have

The music production room is a small cubicle space measuring
l w h = 3,67m x 3,75m x 2,7m

Image

Currently the space has no acoustic treatment apart from furniture. The walls are
concrete and plasterboard, concrete ceiling and parquet floor.

The whole "back wall" consists of shelves with open wardrobe, books, records and magazines. From what I remember of Mike Seniors Mixing Secrets, shelves like this actually work ok as sound diffusors and absorbers, wich is good as I cannot really place any extra absorbers on this wall.

Position of the furniture are fixed, meaning I'd like to avoid moving those around. I know the listening spot isnt ideal, off the room center axis, and the speakers with "closed backs" (no rear facing bass ports) are placed on a desk only ca 20cm from the wall.


Goal

With these given circumstances I am looking for acoustical improvement by relatively small means, and also trying to find a solution I can live with in terms of aestetics (I prefer not having the whole space full of absorbers).

This is a DIY operation on a low budget.


Measurement

A friend helped me to measure the space at the sweet spot.

Screenshots from Room Eq Wizard:
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REW mdat
http://levander.dk/korv/SOS/Jul 13 17_06_06.mdat

Theres is a number of spikes in the waterfall at the low frequencies 100Hz, 137Hz, 182Hz, 335Hz... A large RT60 peak at around 60Hz.

Further up in the the spectrum there is a peak at about 1,15Hz.

I am not sure how to interpret and react to this, but certainly you dear reader, understand this far better.



Taming the bass

I read that for porous absorbers you can lower the "absorbed" frequency by increasing the air gap, following the quarter wavelength rule of thumb.

In order to reduce that 100Hz peak with porous absorbers I would need an 80cm gap, which is quite crazy for my little room. I thought of perhaps creating that gap behind a horizontal panel hanging from the ceiling (I don't know if that would help for bass though), but as the room height is only 2,7m high I don't want to hit my head in that absorber. I could live with a 10cm Rockwool panel with a 40cm gap behind, but that wouldnt reduce anything below 200Hz? Any suggestions? I really don't know how to deal with this bass issue.


Attempt

I decided to start from the other end and take a more aestetic approach.

This is what I came up with.
Plan drawing
Image
3d view
Image

Four symetrically wall mounted porous absorbers, using Rockwool Sonorock panels measturing 0,6 x 1,0m with a 10cm thickness and a 7cm gap behind (so I can at least reduce that 1,15kHz peak). I would like these to be flush with the wall, so I would have that air gap behind a wooden frame.

I read that corners are problematic, so in the two exposed tridheral corners I planned to put two porous absorbers. The sides of the front triangle measuring 50cm and the depth being 22cm at the deepest. Again using Rockwool Sonorock.


Input

Any feedback/advice is very welcome!
erkperk
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Re: Production studio acoustics first aid

Postby James Perrett » Thu Jul 16, 2020 11:49 pm

A couple of thoughts...

It looks like Sonorock is the German equivalent of Rockwool Sound Insulation Slab in the UK which is unlikely to be dense enough to be optimal (they don't publish any density specs so I'd assume the worst). The best density for the wall panels is going to be 60kg/m3 which is known as Rockwool RW3 or Rocksil RS60 in the UK. Your wall panel positions look sensible but, if it is possible, it might be worth making them movable to start with so that you can experiment with the best position.

Your corner traps are far too small to be effective. If I was doing this I'd probably fit 600mm wide panels across the wall/ceiling corner all along your front wall and all the way down the front/side wall corners - which is exactly what I did in my room as you can see in the picture below.

Image
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Re: Production studio acoustics first aid

Postby Sam Spoons » Fri Jul 17, 2020 10:30 am

Firstly I think you are over thinking it a little, you are unlikely to get a flat plot in a room that size (or, actually most sizes). Certainly the bass will be wayward below the low mids, it's unavoidable and you need as much bass trapping as is practical. James' studio is a good example of what can be done if you have a dedicated space.

The good news is that you have done your homework and you basic plan is fine* and the bed will act as a sort of bonus bass trap. What you are missing in your 3D view is a ceiling cloud (I know you mention it in the text) at the ceiling mirror point.

Lack of symmetry is unavoidable in your room so as James says some means of trying the panel positions out before fixing would be worthwhile.

My room is a little under 4 x 4 m but only 1.88 high, I have seven 50mm thick panels spaced 50mm off the walls/ceiling, mostly 1200 x 600 mm and three fairly large bass traps, floor to ceiling in the front corners and a 1400 x 900 mm x 200mm trap in an alcove behind the monitors. I have room to fit a few more panels which I intend to do to cure some flutter echoes away from the centre of the room but I have resisted measuring the room as it sounds pretty decent. I have done pretty much what I can and suspect measurement plots will just lead to disappointment.

* edit :- that makes out sound like I really know what I'm doing, I don't other than having built my own studio and done a hell of a lot of reading :) +1 for RW3 BTW, I don't know why they market the acoustic rockwool as such, on paper it certainly is not going to be as effective as RW3, RW5 (100 kgs/m3) or RW6 (140 kg/m3). Sonorock is only around 33 kg/m3.
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Re: Production studio acoustics first aid

Postby erkperk » Fri Jul 17, 2020 8:09 pm

Thank you so much for your valuable feedback! I will take all this into consideration!
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Re: Production studio acoustics first aid

Postby Sam Spoons » Fri Jul 17, 2020 10:34 pm

You're welcome, please let us know how you get on. :thumbup:
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