How I built my bass traps...

[R_O]

It's just a matter of Mass, if you will. Mass will isolate sound. The denser the mass (heavier) the more it'll isolate in the low frequency range. So basically, by adding a sheet of plastic (not too much mass) you'll isolate higher frequencies a bit from the absorbing material. Adding more mass will isolate it better and even lower in frequency. The energy gets reflected back into the room. Low frequency, as you should know by know, is harder to "isolate", so plastic will do squad in that case; resulting in a bass-only-absorber (well, sorta)

[666666]

Originally Posted by JouCalle

The plastic (reflector) moves along with lower frequences but cannot move as fast as high f so they bounce of, maybe?

I need to understand this! :P

I'm no scientist, but...

Just imagine a large sheet of super thin plastic only (like plastic food wrap), hanging in front of a door opening. Regardless of how it may vibrate, I don't see how it could effectively absorb low-end. If it does, it would be such a minimal amount that it would not be audibly detectable.

But since the plastic does have a bit of mass technically (very small amount), it does reflect something... the very highest of highs... whatever super short frequency wave-length it's small mass / thickness is able to interrupt. This is something that CAN be detected by ear... I know because I've tried it. If you cover an open room frame with plastic only and step inside, you WILL hear very high frequency reflections.

As far as using plastic in a bass trap where the plastic is covered with at least 3/4" of fluffy batting material, I don't see how the plastic will reflect anything because, let's say the plastic would have reflected 10kHz and up, the 3/4" batting would absorb the 10kHz and up before it even hit the plastic, and everything below 10kHz will just go right through the batting and plastic like it wasn't even there... the ultra thin low mass plastic cannot interrupt longer waves.

Then just make sure to have some good dense absorption material behind the batting and plastic to eat up the longer waves / lower frequencies.

Anyway, this is all just per my understanding, I am not a scientist and am not proclaiming that any of this is 100% correct. I am however building some custom traps based on these ideas that I will soon be putting to the test and will report back. I may not do any scientific measuring, but will test musically... and if it SOUNDS good, it IS good.

[Classic]

On building SuperChunk style bass traps in the corners with the triangles floor to ceiling, are these triangles flush against the wall?

[R_O]

Originally Posted by Classic

On building SuperChunk style bass traps in the corners with the triangles floor to ceiling, are these triangles flush against the wall?

Sure.
You can leave a gap if you want, no problem. Remember: deeper traps means deeper absorption.

Check out one of my basstrap designs, it shows a gap behind the wool too: (sorry for the dutch language ;) )

[Keith Moore]

A few questions to the DIY'ers:

Do your bass traps have to be filled to the corner?

If using panels for corner bass traps:
A) How thick should they be? B) Do you have to cover from floor to ceiling?

When using corner panels to cover areas where wall meets ceiling how thick should these panels be?

When using wall panels:
A) How thick should they be? B) should they be a certain distance from the wall or can they be flush?

Does anyone know what is inside Realtraps?

Also just to get a reaction. How much of a difference does using OC703 made panels make over using Auralex products?

Thanks and I'm looking forward to all of your answers,

Keith Moore

[vegafreak]

Originally Posted by R_O

Sure.
You can leave a gap if you want, no problem. Remember: deeper traps means deeper absorption.

Check out one of my basstrap designs, it shows a gap behind the wool too: (sorry for the dutch language ;) )

very helpful, thank you

[droogs]

what u guys think of using this for a absorber inlay
rather than hemp or other bio stuff?

http://www.harrer.at/PortalData/52/R...ndbuch/2-3.pdf

density ca.45kg/m³
sorry for the big pic

[Oni]

Hello lads,

this is my first post. I'd like to congratulate all of the "builders" for uploading pictures, not everyone does that, and most of the times it's really helpful.
I'm beginning construction of my absorbers first thing in the morning. I have two quick questions: I'm planning to use 2 layers of 50mm (40kg density each) rockwool for each panel, is this a problem (I read that 60-70kg density is ideal)?

The second question is: should I post my progress and pics here on this thread, considering it seems to be the most comprehensive about bass traps/absorbers, or should I start my own thread?

[dykstraster@gmai]

Originally Posted by Keith Moore

A few questions to the DIY'ers:

Do your bass traps have to be filled to the corner?

If using panels for corner bass traps:
A) How thick should they be? B) Do you have to cover from floor to ceiling?

When using corner panels to cover areas where wall meets ceiling how thick should these panels be?

When using wall panels:
A) How thick should they be? B) should they be a certain distance from the wall or can they be flush?

Does anyone know what is inside Realtraps?

Also just to get a reaction. How much of a difference does using OC703 made panels make over using Auralex products?

Thanks and I'm looking forward to all of your answers,

Keith Moore

Must the bass traps fill the corner? no

the type that does fill the corner is typically called a "super chunk". Take a 2' x 4' sheet of rockwool or OC703 or OC705 and cut it in half (2' x2'). Now cut that sheet diagonally forming a 90 degree equalaterial triangle. repeat. Stack the sheets into a corner and cover with fabric. Keep in mind, with 2" thick product (typical), you will need 12 full sheets to make a single bass trap 8' tall.

re: panel "straddle type" bass traps

How thick should they be? 4" - 6" is typical, however, the thicker you can afford, fit, and manage, the better.

Do they need to run from floor to ceiling? Short answer, no. But as with thickness the same answer applies, the more coverage the better.

re: wall panels

How thick should they be? 2" is typical, but as with bass traps... thicker = better

Should they be a certain distance from the wall or can they be flush? They can be flush, however an air gap, (generally not exceeding more than half the thickness of the panel), helps to lower the effected frequencies...but... thicker material will always trump air. Example:

2" thick flush to wall .... good
2" thick material with 1" of air gap .... better
3" thick flush to wall .... best
3" thick with 1" air gap ... better than best
4" thick material flush .... bester than best....etc....

Does anyone know what's inside Realtraps? yes

Difference between 703 and Auralex? significant, and this is speaking from experience with both products, in the same room. Clearly, night and day. A more interesting debate is that of Rockwool v 703 v 705... For me, it was a matter of cost. OC is so more expensive here, that while 703 would have out performed it on a sq. inch to sq. inch test, I could have only afforded half the material. Given that formula, Rockwool's 2" to 703's 1"... Rockwool wins. But generally speaking, Rockwool works good in traps that have an enclosed frame, because it is a bit more crumbly. 703 LOOKS better with exposed edges, because it holds it's shape a bit better. Speaking of frames...

Odds and Ends

Frames are purely for looks and mounting...they aren't even really necessary, and in fact, the less of your absorption you have touching a wooden or metal frame, the better it preforms.

Fabric is only for looks and keeping the absorption fibers encased. Breathability is the key here.

Sq. footage of coverage trumps cubic footage of thickness. Example:

you are better off with 16 linear feet of 4" thick traps, than you'd be with 8 linear feet of 8" thick traps

Anytime you take chunks of fiberglass or mineral wool insulation and stuff it into the corners and line the walls of your studio, it is going to make the room sound better than it did when it was bare or covered with foam. Period. The more material you can afford to buy, the better your results will be. Obviously, placing it willy nilly is not a good idea, hit the corners first (all 12 of them), hit the early refectioins at listening position, and sprinkle in some more on bare parellel surfaces, including the floor and ceiling if applicable (uncarpeted floor)

[karma22]

hi guys,

first of all:this thread is awesome!!Thank you all for your contributions!!

[ZuteMan]

Long time reader, 1st time poster here. Great thread. Lot's of creative/innovative DIY-ers and incredibly helpful pro contributors. I'm learning and improving as a result. Thanks to all.

I made 4' X 2 ' X 4" broadband absorbers to straddle all four corners of my small mix room. Ceiling is 9 ft. high. I know optimal coverage would be floor to ceiling but I can't do that right now.

QUESTION #1: Is there a "best" height to mount the absorbers?

Also, I made 4' X 2' X 2" broadband absorbers for the "cloud" to be ceiling mounted above my mix position. Everything I've read on here says hang it 2" from the ceiling. My problem is a ceiling fan.

QUESTION #2: Other than removing the ceiling fan, what is the 2nd best alternative and will it be effective?

I'm clear on the placement of the absorbers for the 1st reflection points.

Advice would be greatly appreciated.

Thanks,

Zute

[dykstraster@gmai]

Originally Posted by ZuteMan

Long time reader, 1st time poster here. Great thread. Lot's of creative/innovative DIY-ers and incredibly helpful pro contributors. I'm learning and improving as a result. Thanks to all.

I made 4' X 2 ' X 4" broadband absorbers to straddle all four corners of my small mix room. Ceiling is 9 ft. high. I know optimal coverage would be floor to ceiling but I can't do that right now.

QUESTION #1: Is there a "best" height to mount the absorbers?

Also, I made 4' X 2' X 2" broadband absorbers for the "cloud" to be ceiling mounted above my mix position. Everything I've read on here says hang it 2" from the ceiling. My problem is a ceiling fan.

QUESTION #2: Other than removing the ceiling fan, what is the 2nd best alternative and will it be effective?

I'm clear on the placement of the absorbers for the 1st reflection points.

Advice would be greatly appreciated.

Thanks,

Zute

In terms of bass absorption, you are best off with the traps all the way to the ceiling, or to the floor, as this will cover not only the wall/wall corner, but also the tri-corner including either the floor or ceiling. Given your ceiling height, however, if you place it either all the way up, or down, you will likely be leaving a bare surface at ear level. If the corners of the room are a good distance from your listening position, (or recording area), place them in the tri-corner. If it is near one of the above mentioned areas, place them so they cover you ear's (or microphone's) reflections.

In regards to the cloud, the air gap would maximize the trap's effectiveness at lower frequencies. Given your situation, I would mount the traps directly to the ceiling... or purchase a down tube extension (most ceiling fans can utilize them) to allow the clearance for the trap. Assuming of course this doesn't create a head bumping problem.

[mobilemozart]

Originally Posted by Lemonsqueezer

I do love this part of the forum. There's a real good vibe about it.

Things can get a bit heated over converters and pres elsewhere on the forum but you can always come back here where there is much love

[ZuteMan]

Originally Posted by dykstraster@gmai

In terms of bass absorption, you are best off with the traps all the way to the ceiling, or to the floor, as this will cover not only the wall/wall corner, but also the tri-corner including either the floor or ceiling. Given your ceiling height, however, if you place it either all the way up, or down, you will likely be leaving a bare surface at ear level. If the corners of the room are a good distance from your listening position, (or recording area), place them in the tri-corner. If it is near one of the above mentioned areas, place them so they cover you ear's (or microphone's) reflections.

In regards to the cloud, the air gap would maximize the trap's effectiveness at lower frequencies. Given your situation, I would mount the traps directly to the ceiling... or purchase a down tube extension (most ceiling fans can utilize them) to allow the clearance for the trap. Assuming of course this doesn't create a head bumping problem.

Thanks much. You've answered my questions and I now know what to do.

-Z-

[xyrium]

Hi, new to the forum, though not entirely to sound correction. From the products I've seen, nothing really does much below 80Hz, would that be correct (including OC 705)?

[avare]

Originally Posted by xyrium

Hi, new to the forum, though not entirely to sound correction. From the products I've seen, nothing really does much below 80Hz, would that be correct (including OC 705)?

No. It depends on the thickness. Rw3 (brtitish mineral wool equivalent of 703) is flat down 50 Hz when 12" thick. BBC published tests.

Andre

[xyrium]

Thanks for the reply! I was under the impression that it's not the thickness, but the density that allows the lower frequency absorption. Therefore, 12" wouldn't matter if the density is only 1 lb./ft.

[avare]

Originally Posted by xyrium

Therefore, 12" wouldn't matter if the density is only 1 lb./ft.

That density would be about ideal at that thickness.

Andre

[xyrium]

Thanks Andre!

[takman]

Great thread...i just skimmed through every page...

i have a question...

I want to install super chunks in the corners of my room. From the floor to the ceiling ( ceiling height is 9' 9"). but i have thick crown moulding on the ceiling. So the super chunk would end about 6 inches before it reaches the top of the ceiling, leaving a 6 inch gap between the top of the SC and the ceiling.

would that be detrimental to its performance?

I really dont like the crown moulding in my house, but i cant remove it. I was thinking of using auralex versatile ( although its way overpriced) to cover the moulding in the corner above the superchunk gap. because the verstile is like crown moulding, and its large enough to fit over my existing moulding.

Also, i can only make the super chunks 1" x 1" x 17" instead of the recommended 2", because of a window and other obstacles. is that going to be thick enough?

[Pretension]

Hey guys, I must say I am well impressed with this forum and this thread. I have taken to many tips over the last few weeks and I have finally gotten around to building my own acoustic panels. Here is a quick pic of my modest studio.



I've also started doing a writeup on the process if any of you guys are interested.

Pretension // News & Production Blog

I am forever grateful of this resource. Keep at it guys!

[sevansounds]

I have a question regarding using the side of the owens corning with the foil wrapper on one side or using the 703 with the bare board facing out.

If I am going to be using 3 panels equalling 6" in each of the corners going up to the ceiling to act as bass traps (front floor to ceiling is 8ft equaling 6 total panels per corner and back 12ft equaling 9 panels per corner).

On top of that....

2" panels in my first reflection points (1 on each side wall, 2 on ceiling above mix position, 1 each on wall behind monitors and a 4-6 panels to cover the bare back wall......

My question is this..

With all of this absorption in the room, to not make the room too dead sounding should I flip some of the panels so the foil is facing out to reflect some highs?? I read this in earlier replies but I'm not sure WHICH of the panels I should flip so foil faces out?

My current guess would be to only flip the first panel of each of the bass traps so that the side facing out in the room is the foil side and leave the first reflection point traps with bare panel facing out or flipping all of the bass trap panels foil side out?? I'd like to get some advice before I put the panels in their frames.

Thanks everyone and keep up the awesome community of greatness.

[sevansounds]

Any suggestions??

[Ethan Winer]

Originally Posted by sevansounds

leave the first reflection point traps with bare panel facing out or flipping all of the bass trap panels foil side out?

Yes, corner bass traps should all have the foil facing toward the room. Reflection absorbers should all have either no foil, or have the foil next to the wall so they absorb fully at mid and high frequencies.

--Ethan

[takman]

Originally Posted by sevansounds

Any suggestions??

i havent received answers to my question yet as well..but dont worry, they will get around to it...sometimes it just takes a bit.

If you are going to have the foil side facing out, i would do it on the bass traps, not on any first relfection points. ( ceiling cloud, 1 reflection side panels, rear wall reflection panel etc)

I think it depends also on whether if you have carpet or not, what the walls/ceiling are made of. etc..

For myself, i have cement tile floor and plastered brick walls, so my room is going to be really live. So, using rigid fiberglass with the foil facing out would probably not deaden the room enough for me.

Also, you could build the trap/panel frames in such a way that you could remove the insulation easily, so that you could flip it around. i had thought about constructing mine in that manner, because i will be using RF that not too many people are using, so in case i didnt like it, i could remove it later on.

Anyways, im no expert, but i think other might tell you the same. And really, it might just come to down to, having to experiment until you get the liveness or deadness where you want it.

good luck.

EDIT:

ok, ethan just posted right before i finished writing this and confirmed my thoughts lol

[Gharper23]

I also have a quick question about the paper on the front of the 703. I am doing 10 traps for the room. all 4 inches thick. 2x4 frames. Im not really sure if i should use the paper on the insulation or just use the insulation bare.. the room is 14x13, carpeted. 9 foot ceilings. drywall. Which would be my best bet? This is the only thing keeping me from starting these, already have the frames done.

[sevansounds]

Thank you guys!! and pretty gals : )

[Gharper23]

Never mind I found my answer after reading some more. The corner bass traps will have the frk on the one outside piece of insulation and the first reflection points will have no frk. Sounds good to me

[mr-b]

Hi

I'm wondering which fabric is best to use to cover the panels, especially for decent HF absorption.

I saw earlier in the thread that Ikea Ditte has been used by some, but it does seem to have quite a close stitch compared to hessian (burlap) e.g. you can easily see through hessian but only bright lights through Ditte.

I have heard conflicting advice about how to test the fabric for suitability i.e. some says that you should be able to breathe through the fabric, and elsewhere that you should be able to blow through it. Hessian is a lot easier to blow through compared to Ditte.

The Ditte fabric does look a whole lot better than hessian and is available in a good selection of colours so it's preferable in those aspects (hessian can look rather agricultural!). I can't find Guilford of Maine anywhere in the UK.

[Gharper23]

My traps are coming along great! I have 4 down 6 more to go. This isn't the room I am putting them in but just have them in here for pics. They turned out better than I expected. They ended up costing me $25 each to make. Got the oc703 and fabric pretty cheap.

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