Placement of Bass/corner Traps

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Placement of Bass/corner Traps

Postby Hulk » Sun Feb 15, 2004 8:18 pm

Hallo
This is my first post so be gentle :-) (I'm from Denmark so be gentle on my spelling and grammar too hehe!!)
My friend and I are building a studio in his garage. The control room is small only 8 fett long, 11 feet wide and 7 feet high and when we talk in the control room it sounds boomy already. Because of the size of the room the monitors has to be placed right up against a brick wall (I have uploaded a home made picture of the control room - use this link http://www.ocupload.tk and clik on Controlroom.JPG)
As you can see I have made dotted lines where it is possible to place corner traps but I don't think that is enough (please remember I'm a complete novice in the field of acoustics and only two months ago I thought that acoustics was a minor thing in a studio) so I want to place 2 or more home made bass traps (design made by Ethan Winer from Real Traps) The control room has wood floor and ceiling.

a) Since I don't have much room for corner traps is it generally a good solution to place Bass Traps in the control room??
b) Is there any (simple) way to make measurements so I roughly know how much area there has to be treated with bas traps and acoustic foam (pyramid shaped)
c) I read at studiotips.com that I could sit in the mix position and move a mirror along the walls and where I could see the monitors those areas needed acoustic treatment but would acoustic foam be enough??
d) Any advice is more than welcome!!


Thanks
_
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Postby Bob » Sun Feb 15, 2004 10:38 pm

I don't know off hand how to measure it. http://www.etfacoustic.com/
I agree, measure first, add treatment second. Then compare both with software and humans.

Your room is 8'x11'x7' tall. That's 616 ft^3. That's a small room.
You have doors in two corners, and a closet in a third corner. Presumably the closet eats up another 70 ft^3. Portable corner traps have been mentioned for corners with doors (a frame with wheels, or a 2" panel of 703 mounted on a piano hinge so that it becomes a corner absorber over half the door).

Having looked at your room, I have no recommendations for it. Perhaps others will. Most people here know a lot more about acoustics than little ol me. From this site's home page, study the text in the Acoustic FAQ area. Maybe you'll see something that'll help.

The wood floor is good. If you and your friend are short, then perhaps a lot of insulation could go into a false ceiling, making a big and deep absorber up there (as much as the entire ceiling, a foot deep).

I think that the rockwool corner traps are better bass and broadband absorbers than panel bass traps. You might want simple absorber panels on the 'back wall' at the mirror points instead of where you've written 'bass traps'.

SteveFoster's ABC's of Room Design are:
So my ABC approach to room treatment for the DIY'er stands: 1)keep all absorption broad band to the very end - treat specific frequencies only if you can find no way around it; 2) start in the corners, floor to ceiling, panels as wide and as deep as you dare - catch em all big and small; 3)treat the front of the room for early reflections with absorption / front wall-ceiling shaping / adjusting mix-speaker position / voodoo dolls]; 4) defeat flutter [either absorbers, or diffusion] keeping in mind that if you have a flat ceiling, the floor to ceiling flutter is by far the largest area
of parallel flat surfaces and therefore probably needs the most attention; 5) Add broadband absorption to hit your desired RT60 [wall panels / clouds / ceiling grid]
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Re: Placement of Bass/corner Traps

Postby Paul Woodlock » Mon Feb 16, 2004 12:01 am

Hulk wrote:...
a) Since I don't have much room for corner traps is it generally a good solution to place Bass Traps in the control room??


Greetings Hulk :)

Take a look at the horizontal corners. Between the walls and the ceiling. Corner traps don't have to be vertical between two walls.

Horizintal corner traps might requrie more effort to mount them, but I bet they are just as effective.

Corner traps are broadband, rather than aiming at specific frequencies, so I wouldn't think it's much of a risk installing them without measurement.


b) Is there any (simple) way to make measurements so I roughly know how much area there has to be treated with bas traps and acoustic foam (pyramid shaped)


I use ETF ( bob gave you the link ), with a Berhinger ECM-8000 measurement mic. ( only Behringer product I would ever recommend :) ]

It works really well, once you get used to the strange window behaviour


[b]c) I read at studiotips.com that I could sit in the mix position and move a mirror along the walls and where I could see the monitors those areas needed acoustic treatment but would acoustic foam be enough??
Thanks


While corner traps are commonly used to even out the Himalyan freq response caused by room modes, the mirror trick is used to pinpoint the areas which cause early reflections for the mid and highs too. ( Early reflections are those which are too early for the brain to distinguish as a seperate sound. They mess up the freq response as well as the stereo image. And probably a few other things. )

Even without a mirror the usual place for early reflections are on the side wall and ceiling between the mix position and the speakers, and the wall behind the speakers.

So yeah, get a friedn to move a mirror around all surfaces, and whereever you can see the speaker(s) this is the place to put up absoprtion ( prefereably with an air gap behind it )

And as your room is classed as SMALL, you will probably get early reflections from the back wall too.

With the low ceiling at only 7 foot, if you put up a lot of absorption up there and an airgap, you 're gonna make the place a little uncomfortable to work in. ( unless you are all dwarfs :) )

Although you could put up a 'cloud' of absorption on the ceiling between the mix position and the speakers, angle it down towards the top of the window, without intruding too much


Paul
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Postby Bob » Mon Feb 16, 2004 12:06 am

Cool Paul. Horizintal corner traps. I didn't think of that. When in doubt, look up!
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Hulk » Mon Feb 16, 2004 9:32 am

Thanks for your answers

After starting to read about acoustics I wish I was a dwarf but no no I'm 200 pounds of pure muscle hehe sorry could not help my self :-) but seriously
a) Would it be a major advantage if we did not placed the closet in the control room? (It was an expensive and specially designed closet so it has to be a major acoustically advantage!!)
b) If the Rockwool plates has a thickness of 3cm (1,18 in.) and an airgap behind them of 1 in. would that be sufficient when treating the ceiling above the mix position?? I'm planing to use 5cm (2 in.) plates for the vertical and horizontal(great idea!!) corner traps is that a sufficient thickness??
c)I will also recommed Behringer ADA8000 :-)

Thanks again!
_
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Postby Bob » Mon Feb 16, 2004 4:15 pm

Hulk:
Your first post said your room sounds boomy, as in too much bass. So filtering out more high-frequency would be bad. Therefore your primary treatment of (b) ceiling idea of 1" rockwool 1" down would be bad.

Remembering measure first, build second, and only take my comments if you agree with them, using variations based on availability of materials:

I suspect that this combination may be your options:
a) remove the closet
b) in the un-doored corners, build filled diagonal corner traps floor to ceiling using 2'x4'x2" panels of rockwool/fiberglass cut into four (cut them into 2'x2', then cut them diagonally making triangles). Then, if optionally if it's still boomy, try 4' across the diagonal in front of the triangle panels of 2'x4'x4" panels of rockwool/fiberglass (very deep cavity)
c) around all four walls at the ceiling build horizontal traps using 2'x4'x1" panels of rockwool/fiberglass.

Then add little 2'x2'x2" set 2" out from the wall/ceiling of fiberglass/rockwool at the mirror points (sides, back, ceiling) to get rid of first reflections.


If you have no money and no time and don't care what it looks like, then there is an experiment you can try. Pop off to home hardware wall insulation store and buy four or eight big bags of fiberglass pink (fluffy wall) insulation. Bring them home. Stack them two high in each corner. Leave them in the bags. See how that works. If you don't like it, then return them.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Scott R. Foster » Mon Feb 16, 2004 5:16 pm

Hulk:

You need to muff that room out big time.

Get thicker panels - lots of em.

My $0.02
SRF
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Postby Hulk » Mon Feb 16, 2004 10:55 pm

Ok Thank you all for the advise!!
_
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Postby backountry » Thu Feb 26, 2004 12:51 am

hulk
my room is 9.2ft wide x 11.3ft. long x 7ft. high and i use it as a single track record/mix room. i have been the panel trap route and would recommend that you could make you life a lot easier if you started first and foremost with the following.

broad band absorption in all or as many of the corners as you can from the floor to the ceiling or as much of that area as you can. these are the rockwool/703 rigid glass units described at this site. mine are now three feet across the diagonal. i personally choose to fill the inner cavity with as much rigid glass as i could afford. next do your mirror test and install absorption at those areas. i choose absorption because as scott is saying this size room needs to be absorbed big time. i installed 1 1/2" thick panels at these locations and i plan to increase them to 3inches. your ceiling is a big concern. i was able to install tectum on 2" x 6" storage joists above. they should have been filled with fiberglass. with a reflective floor as yours you could benefit from a very absorbed ceiling. over my mix position i installed 1 1/2" 703 rigidglass on the 2" x 6" joists with fiberglass filling the cavity. all ceiling to wall corners have tectum bridging the diagonal space. these too will probably change out to broadband units soon. all of my ceiling area is tectum as is my front wall and 2/3 of each side wall. once you come close to this set up you may wish to think of panel traps or helmhotz resonators to fight the remaining problems.

this site has brought me this far in the last 6 months while i have spent the last 3 years trying to get my room to respond well and be transportable. i can now record acoustic and vocal and my mixes on cd are starting to sound like what i mixed in the room. i most admit that prior to replying, i did not look at your design area so hopefully this will help you in your decisions on your own space. good luck...

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