Building Bass Traps, a chronology.

[arcadeko]

Ok, so I ordered my materials today and purchased my fabric. Lucky for me the fabric store had the Halloween stuff out already so I got some stuff that looks like it was made out of all my old back t-shirts from the 90's... (It's actually two layers, the top layer has the holes in it - looks straight out of a Bela Lugosi movie! Awesome) Also picked up some Fireguard spray to make it flame retardant.

I am making 7 Panels, Five 2' x 4' x 4" and Two 2' x 2' x 4"

3 panels will go in the corners, one for a ceiling cloud, one center rear wall and the two small ones left and right for early reflections.

I ordered two packs of Roxul AFB

Item: Roxul Acoustical Fire Batts, Mineral Wool, 2-inch, Case of 6
Quantity: 2

I think I am going to go with the corner bead frame if I can find an easy way to attach the fabric. Otherwise I will make wood frames out of 1x2's.

The AFB should arrive later in the week, I am guessing by Thursday? So I will chronicle my adventure with film - anyone who wants to throw in suggestions or cheer me on is welcome to do so

 

[arcadeko]

I have these two guides - The metal seems lighter and less hassle cause I don't need to get out the saw, but the glued fabric doesn't seem very clean - also seems like a pain in the ass to get the eye hooks to stay in. I think hanging the wood ones would be easier? Of course the guy might have just been sloppy - I want them to look professional - I'm spending all this time and money making them, might as well make them as perfect as I can...

Wood Framed Bass Traps
http://www.basstraps.net/DIY-BASS-TRAPS-MADE-EASY.pdf

Metal Frame Bass Traps
Steven P. Helm: DIY Bass Traps

 

[Capriccio]

I am making 7 Panels, Six ... and Two ...

7 = 6 + 2

3 panels will go in the corners

How many corners does your room have? And is your room only 4' high? Corner traps should go from floor to ceiling (or vice versa). The most effective place for traps is in the tri-corners, where wall, wall and ceiling meet, so don't leave a gap above the traps.

... anyone who wants to throw in suggestions or cheer me on is welcome to do so

"... the typical home studio needs only between 30 and 40 percent coverage to adequately treat it." Source: A Beginners’ Guide To Acoustic Treatment. What percentage of your room will you be treating?

I look forward to following your chronology.

 

[arcadeko]

7 = 6 + 2

Doh - 5 + 2 is what it should have said... it's fixed now thanks for catching that. 5 full panels and one half panel.

How many corners does your room have? And is your room only 4' high? Corner traps should go from floor to ceiling (or vice versa). The most effective place for traps is in the tri-corners, where wall, wall and ceiling meet, so don't leave a gap above the traps.

The room is a bit wacky because it has 2 doors right at two of the corners. I am going to try and make a 3-d model of it to post here. I have thought about making triangle wedges for the tri-corners at the ceiling but I am still strying to figure out if that would be any more effective than just having the 2x4' panel run all the way to the ceiling.

"... the typical home studio needs only between 30 and 40 percent coverage to adequately treat it." Source: A Beginners’ Guide To Acoustic Treatment. What percentage of your room will you be treating?

I look forward to following your chronology.

Ok lets see - it's a 12 x 14 room with 8 foot ceilings. so that makes about 640 sq feet of surface area. I purchased enough material to make 6 2x4 bass traps, so that makes 48 sq feet. So that is less than 10% - for 30% I would actually need 200 sq feet of coverage? Which would be about 25 2x4 panels - so I am far from that - but because of the room I really don't have enough room for that many panels - I could probably fit 12 if I covered most of the available walls and ceiling.

Are you supposed to calculate the floor and ceiling in that 30% number? I included it above. Not sure how much the carpet and rug on the floor affects the high frequencies.

 

[grimtraveller]

So anyone who wants to cheer me on is welcome to do so

Go, go ~ Deko !

 

[arcadeko]

Ok this is the basic idea. - the entire fore wall that you can see through is actually mirrored closet doors that stretch the entire length of the room (with the exception of a wooden fold-in door in the center that is about 24" wide and separates the 2 6' wide mirrored sliding closet doors). I can't install a corner trap on either of these fore wall corners. The ceiling is actually split level and is dropped 1 foot - it runs the 4' from the fore wall to just past the door openings, and the entire run of the room parallel to the fore-wall you are viewing the model through.

This is my initial idea for placement - this is using all double layered traps to make 4" traps - except for the two small panels and ceiling cloud which would only be 2" thick. So I guess I am actually making 8 panels... Not sure - also the one wall that has the corner trap from floor to ceiling is not accurate - I am going to cut those short so I can notch out a little table surface in there. So the model shows two 4 foot traps running floor to ceiling - I will probably make a 3' one for the floor, then leave a 2' opening and put another 3' trap above. This will give me enough material to make the 2x2 side panels.

After doing dome measurements, I think that 2' wide corner traps will take up too much space in the corner behind the drums - I am going to have to reduce those to 1.5 feet wide (18" instead of 24").

 

[1llogic]

Wow nice rendering! How did you accomplish that ha?

 

[arcadeko]

Wow nice rendering! How did you accomplish that ha?

Google Sketchup - pretty sweet free modeling program - but it is a bit addictive and I just spent the last 4 hours messing with it... I replaced the old renderings with the new one after I realized I screwed up the measurements - the ones above are now much more accurate (i even used a photo of the fabric for the bass traps).

I modeled my actual desk (less legs) - I decided to use 2" traps on the back-wall, the ceiling, and the 2 small side traps - only the 4 corner traps are 4".
I remade all the corner traps 18" wide and 3' tall (room for shelf). The two openings show the closet doors - there is another 30" in the room that is now behind closet doors - I figure I can just slide the doors open a foot or so and that should disrupt the corner so it doesn't accumulate too much bass (since I can't put a trap there and still get into the closet.

I think this will give me a pretty decent treatment and keep most of my sound waves under control.

If anyone has suggestions please let me know - AFB Rockwool should be here this week so I will be building these over the weekend (maybe before).

 

[Capriccio]

Are you supposed to calculate the floor and ceiling in that 30% number? I included it above. Not sure how much the carpet and rug on the floor affects the high frequencies.

Yes, include all boundary surfaces. 30% is a guide, so 10% is better than 5% and being a guide, your room may not need 30%. have you or are you planning on acoustically measuring your studio? It will be easier to treat what needs treating that to guess or follow general guidelines, which are a good starting point but not specific to your studio.

A carpet is not a good idea as it will soak up the higher frequencies but doing nothing for the bass - because it is not thick enough. The usual method is to hang traps from the ceiling to absorb reflections, and sparingly use rugs where necessary, leaving the hard floor (concrete, wood, laminate, all are fine) exposed.

In your post, #8, you mention 2" traps. 4" is the recommended minimum depth. Deeper is better. Use 2" at your own risk. It would be a pity to build bass traps only to find that they don't deal with the lowest frequencies.

 

[arcadeko]

Have you or are you planning on acoustically measuring your studio? It will be easier to treat what needs treating that to guess or follow general guidelines, which are a good starting point but not specific to your studio.

I downloaded the software and ran the test - I ended up with a big graph that means nothing to me. I don't think I did it correctly because it looks like a overly compressed mp3 wave with a hard limiter - the graphs people posted on the site were a simple line so IDK - i messed with it for a few hours and threw int he towel. Perhaps I will tackle it again.

A carpet is not a good idea as it will soak up the higher frequencies but doing nothing for the bass - because it is not thick enough. The usual method is to hang traps from the ceiling to absorb reflections, and sparingly use rugs where necessary, leaving the hard floor (concrete, wood, laminate, all are fine) exposed.

Well I don't plan on ripping up the carpet. So I guess I will just have to deal with it.

In your post, #8, you mention 2" traps. 4" is the recommended minimum depth. Deeper is better. Use 2" at your own risk. It would be a pity to build bass traps only to find that they don't deal with the lowest frequencies.

I was planning on making all the corner traps 4" thick. Then I have the cloud and the rear wall - I could make one of those 4" thick and the other 2" - not sure which would be better. The two 2x2' side panels would be 2" thick - Maybe I could supplement the bass traps with some acoustic foam tiles for the walls.

BTW: Thanks Capriccio, I appreciate all the help!

 

[Capriccio]

Maybe I could supplement the bass traps with some acoustic foam tiles for the walls.

Foam? Aaaarrrgghh!!!!! More high frequency absorption, like the carpet and the 2" traps. You will have everything trapping the top end and nothing that is trapping the bass. Your studio will sound awfully sucked and muddy, if you don't mind my saying so.

It's not my room ... but if it was I would make as many 4" traps as I could and then later on, when I can afford to make some more, make more 4" traps. No 2" traps and no foam. Honestly!

 

[arcadeko]

Ok I measured my room:

But I don't have the calibration data for my mic so the graphs are based on a bright mic.
The RED line below is the graph for the MXL 2010 (Omni condenser) mic I used to test the room.

So I got these graphs but they don't really mean anything to me - I don't see any major spikes. Can anyone decipher this graph and infer what I need to do?

 

[1llogic]

Im gonna have to check that software out! Now- I am not at all a acoustics pro, but this is what i think i can remember from 1 year mechanical engineering program.

The 'x' scale you have just must not be very conducive to exaggerating the problems. Everywhere there is a sharp point negative (or dipping down abruptly) relative to the surrounding would be cancelation issues from standing waves (which are dependent variables of your rooms dimensions - So you shoulda be able to measure your room and check the modes and verify those dips on the graph). Everywhere there is an abrupt peak, this is where the reflecting waves are actually joining what you hear in a positive form thus amplifying the wave more then what it really is.

The best way to visualize that graph, and how it is affecting what you hear, is to think of it as an eq getting applied. So that dip at 200hz is acting like you applied a -7db cut at the frequency. And those peaks at ~100 and 160, are as if you have a +10 boost at those frequencies. Which we both probably know is no good!

 

[1llogic]

After checking your designs i would atleast recommend that your corner trap runs to the desk and then another under the desk. Also the full length of that opposite corner not just top and bottom. Corner traps should be solid rock wool aswell. I think i saw somewhere one time a guy just cut diagonals out of small square sections of the fiberglass board and make his corner traps that way. Of coursed wrapped and framed. Doin it this way will provied wayyyyy better, and i stress way better, bass taming!

If you can do 2' across the corners that would provide ~17" of absorption in each corner! Which can fully absorb down to 100hz (Which will basically solve all you issues presented in that graph - provided there is enough coverage!!!! Fixing issues below this would b very hard (id imagine) without some kind of limp mass resonator to finish the job. Which is exactly how real, and expensive, bass traps are made.

I also would suggest a broadband absober between your closet doors!

 

[arcadeko]

Yeah when I zoomed in i found some major peeks and dips - like 20~50 db!!!

I'm gonna have to buy some more Rockwool

I will build up what I have and then do a new diagnostic to compare.

That software is Free here: REW - Room EQ Wizard Home Page

Thanks for the feedback 1llogic

 

[1llogic]

NP. I meant the google software But ya dude that un smoothed graph shows even further that with some nice 4" panels and 2 foot solid corner traps - basically all your problems will be solved besides your cancellation at 95 and boosting at 80-85! Which is alot easier to compensate for in the mix. Just remember you kick thump mite not sound how you think it does! Less felling then you think and maybe a more thickness then you hear

Anyway goodluck! My pacifico is all gone so im off to the store!

 

[arcadeko]

Google Sketchup: Google SketchUp
Thanks dude.

 

[arcadeko]

Decided to pick up another pack of Roxul from Lowes to make a superchunk in the back corner. I will move the corner traps to the ceiling corner. I can't stop playing with Google sketchup

 

[jimmys69]

The low end buildup in front of your listening position is going to affect you the most man. I would super chunk both of them as much as possible. What is the distance between the door and the right corner from your desk? Even with the door open, you are going to get some buildup there. Symmetry is very important too man. Where does that door go? Can you build a portable one to place in that corner and partially block the door?

You realize I'm just giving you an excuse to play with sketchup right? lol!

 

[arcadeko]

The low end buildup in front of your listening position is going to affect you the most man. I would super chunk both of them as much as possible. What is the distance between the door and the right corner from your desk? Even with the door open, you are going to get some buildup there. Symmetry is very important too man. Where does that door go? Can you build a portable one to place in that corner and partially block the door?

You realize I'm just giving you an excuse to play with sketchup right? lol!

I could put a 2'x'4'x4" panel on a stand and use it as a gobo. Those doors get a lot of traffic - there is a hallway on the one by the desk and another room on the other one. Think mopads pads would help? I could probably superchunk the corner under the desk too.