Control Room help (first time builder)

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DeadPoet

DeadPoet

carpe diem
Hi y'all,

I've been reading this forum for quite some time now, but never (dared to) participate..
First of all, introducing myself: I'm a young bass-player, I play for a living, and always had homerecording as a hobby. Little by little however, this is getting more than a hobby, and I'm doing midi- and preproductions for other people.
Now, the time has come to treat my working space, so I started reading all about acoustics, soundproofing, etc.
Since English is not my motherlanguage, I'm having a hell of a time finding online traductions of all these technical terms (yet have to find one traduction for 'drywall', though I found an explanation of it).
On top of that, I live in an old rented house. So any changes I make cannot be permanent, and soundproofing is something I don't even want to bother to do. I mean, when a truck drives by, my wooden floor resonates :D

From what I've learned, I guess I want to make some slot resonators, hanging on my side and front wall, and bass traps in the corners.

Included should be a (bad paintbrush) drawing of my room..


It's a square room (modes calculated: front-back:41,25Hz, left-right 40,24Hz, top bottom: 52,72Hz - RT60 should be about 0,69@125Hz - 1,04@250Hz - 1,3@500Hz - 1,77@1kHz - 1,56@2kHz - 1,27@4kHz)
Front, left and right walls made of plastered brick, back wall plasterboard.
On the left two large windows, with curtains. Ceiling seems to be plasterboard (sounds hollow and I know drilling in it always means heaps of caulc falling down), the floor is painted wood laths.
The back wall is covered with three open bookcases (which already act as a diffusor ??) + solid core door.

Basically, I have the front wall, right wall, 2 front corners and a little bit of left wall available to treat. (moving the bookcases to the right would damage my stereo image, right?).

I've read the SAE-site, Auralex's site, and all these threads + various other sites.

Now, my questions are of the practical kind..

1) the insulation material... here's where my poor English shows, I can't find a translation for 'rigid fibreglass' ... I recon it ain't the same as glasswool (which resembles rockwool) ???? This stuff
isn't rigid.. I seem to be unable to find this material in our Belgian DIY-stores. :(
1b) Does anyone know the ISOFIX material ? It's the confetti-colored
stuff, ~1" thick ?
1c) this is a list of what I could find, I don't know if these are suited:
- 2" Polystyrene panels
- 2" styrodur panel
- 1" fake acoustic insulation
- 2" & 4" rockwool & glasswool panels


2) the SAEsite
shows Helmholtz resonators with the insulation attached to the back of the slats, while John's site shows them with the insulation attached to the wall.
Which one to use ??

3) What actually no-one ever writes about is the height of all panels, absorbers and resonators. should these be floor to ceiling ? (in my case 3,13m - 10,27')

4) If I attach some eyes to the walls, can I hang these resonators or should they really be attached to the wall ?

5) So I would be building two corner absorbers according to John's plans. Now I have NO idea what frequencies I should try to find with the Helmholtz.xls, I just figured, try to go as low as possible, these are bass traps, right ?

6) next up, 2 side wall aborbers (red on the after.jpg). Would the included green proposals do any good if I don't have the back wall absorbers?

7) the covering cloth: will any fabric do ? - the slats: they're mdf too ? or rather pine or any other wood ? (other wood found: hardboard, particle board, MDF, multiplex, 'concrete plywood' (?), OSB and some stuff called 'Ocoume' ?????)

Am I making any sense here ? Have I gotten the point or should I keep playing the root ? :D

TIA,
Herwig
 
should include my plan
 

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Hi Herwig - welcome to HR.

OK - the rockwool is what you want. Just putting that on the wall will absorb down to around 500hz.

The slots are in sealed boxes so if you can't attach them directly to the wall you must put a rear plate on to seal the cavity, 1/4" plywood or similar. This cavity is then has rockwool in it. Just stuff it in, it stops the resonance in the cavity.

The slat sizes are worked out using the helmholtz.xls calculator and you want to tune them to absorb from 500hz Down in a broad band.

cheers
JOhn
 
thanks for the reply and the resonator plans John, they're a great help.

From what I know is it wise to do the following ??

Two corner units on the front wall, about 2m high; two side wall absorbers on the right wall 2100x1200mm and two low-freq panel absorbers on my front wall, also 2100x1200mm and tuned to 40-41Hz.

Are the panel absorbers on the front wall a wise idea? Is having sidewall absorbers only on my right wall gonna pose left-right balance problems ????

So many questions.. Maybe I'll just construct these things and experiment a bit with positioning.


Herwig
 
Dear Herwig,

I'm live in "het Waasland" near Antwerp, Belgium, and I'm currently transforming my attic (zolder) into a small studio. I've done a search for local material availability, and I think I can help you with the following:

The ISOFLEX-stuff is for soundproofing, this format is sold by Hubo, Brico etc... but it comes VERY EXPENSIVE!!!
If you want to use this, try at ISOALL SINT-NIKLAAS (Dhr. Guy De Baer, 03/7776262). They call it "anglofoam" and I believe they can get it cheaper.

For the "fake acoustic eggcase-like stuff": you can find it in bigger formats (and perhaps cheaper, you should check) at Verbiest near Mechelen (http://www.verbiest.be/nederlands/index.htm).

Hope this helps a bit.

Greetings,
The Niz
 
thanks john, I'm going with the local no-brand variety of the rockwool. I kinda know the density required and such.

As I read more & more about absorbers and diffusors, more and more questions arise.. Well, I'm off to building some and just the ol' trial & error.

(btw: i've seen many designs for panel absorbers, some of which where the insulation is attached to the panel, some of which it is required to have some airspace between panel and insulation ????)


TIA,
Herwig
 
Here's my shot at an explanation. A panel resonator is just that. Your paneling which encloses a sealed volume of air resonates at a certain frequency depending on the volume of the cavity and mass of the panel. The insulation is intended to absorb the energy and dissipate it as heat so it doesn't just re-transmit into your room causing more problems than you started with. If the insulation is separated from the panel, the panel will resonate at its normal frequency. If you attach insulation to the panel, your modifying its mass and therefore its resonant characteristics somewhat.

Makes sense to me, but I'm a chemical engineer so what do I know.

Alex
 
thx Alex, I figured that out as well, but check out the differences:

- Ethan Winer's bass traps
- SAE College
- then again this page says in the Low frequency absorbers paragraph that "If you use 703 leave at least a 1/4" space between the panel and the fiberglass or else the panel won't be able to resonant properly."
- which is affirmed by this page.

Basically I guessed that if you use the 703 material as insulation, you'd better have a gap between panel and insulation (can't find 703 in Belgium, I guess it's a really stiff kind of panel). If you use normal sheetrock/rockwool/whatever you call it, then you could fill the entire space (the material being flexible).

Herwig
 
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