ethan winer bass trap

[Pier]

I'm going to build some bass traps for my home studio based on Ethan's design.

Build a Better Bass Trap

I have some questions I hope someone can answer:

1) Will adding some rockwool inside the sealed space improve the absorption of the low frequencies? Is this a bad idea?

2) What about having a few sealed spaces one on top of each other like a sandwich? will that improve absorption?

Instead of | space | (| is the wood panel)

This | space | space | space |

3) Will it loose effectivity if I put some kind of foam or fiberglass over the trap so that can also absorb mid/high frequencies?

| space | foam

4) Have any of you used this design? how was your experience?

Thanks!

[drummerboy1533]

NEVER messwit another mans plans.Build them to specs,place them in a LO,MID,HI,MI,LO arrangement.They are effective for larger rooms,but since I missed that tip, they sufficed in a small bedroom.Now I have the priveledge of using them in a large living room for a home theatre setting.

[Musiclab]

they work very well

[Pier]

Thanks for your input

What about my modifications?

[Ethan Winer]

Originally Posted by Pier

1) Will adding some rockwool inside the sealed space improve the absorption of the low frequencies?

Rigid fiberglass (same idea as rock wool) is already shown in the plans. So that's a necessary part of the design.

2) What about having a few sealed spaces one on top of each other like a sandwich? will that improve absorption?

No - one cavity per trap please!

3) Will it loose effectivity if I put some kind of foam or fiberglass over the trap so that can also absorb mid/high frequencies?

It's a problem only if the foam or fiberglass touches the wood. Isn't that explained in my article? I added rigid fiberglass in front of the wood panel traps in my studio, and it worked well. I mounted them with a 1/4 inch gap so the wood is free to vibrate. Photos below.

--Ethan

[Pier]

Originally Posted by Ethan Winer

No - one cavity per trap please!

Thanks for your answers Ethan.

Why is that only one cavity? would't it offer more resistance?

[Ethan Winer]

If you combine cavities, they'll interact in unknown ways. To work effectively, a panel trap needs a rigid backing. Another thin plywood panel is not rigid. Plus you're expecting bass waves to go through multiple wood layers and somehow magically be absorbed by the correct layer. I can't imagine that ever working.

--Ethan

[avare]

Originally Posted by Ethan Winer

If you combine cavities, they'll interact in unknown ways. To work effectively, a panel trap needs a rigid backing. Another thin plywood panel is not rigid. Plus you're expecting bass waves to go through multiple wood layers and somehow magically be absorbed by the correct layer. I can't imagine that ever working.

Well put in your clearing issues style. The more correct explanation is that every panel that moves and is coupled to other panels, or rigid surfaces will resonant. Calculating the resonant frequencies is well beyond the capabilities of the average slut here. Gearslut that is...

If someone is interested, the three panel equations are in Sharpe, available here. Assemblies beyond that are very rarely used because the calculations are even more complex.

Andre

[TooManyToys]

How short can the panels be and still be effective?

I noted in the article it stated 1/8" ply. Is that really plywood or hardboard? I've never seen 1/8" ply in HD.

[Pier]

Originally Posted by Ethan Winer

If you combine cavities, they'll interact in unknown ways. To work effectively, a panel trap needs a rigid backing. Another thin plywood panel is not rigid. Plus you're expecting bass waves to go through multiple wood layers and somehow magically be absorbed by the correct layer. I can't imagine that ever working.

--Ethan

Hmmm.... ok I forget about doing any cavities...

But that makes me think of another problem.

I don't know how much time I'll be in my place. So I was thinking of doing a closed frame for easier transportation, with wood on front and on the back (your design has only wood on the front), and then attach that to the wall.

I suppose the back wood panel, being in contact with the wall shouldn't be a problem... am I wrong?

[PaulP]

Originally Posted by Pier

I'm going to build some bass traps for my home studio based on Ethan's design.

I have a couple of questions :

What do you plan on achieving with your panel absorbers ? Ie, what problem
do you have now that you plan on solving with them ?

How do you know how many you'll need ?

4) Have any of you used this design? how was your experience?

I believe very few members here have attempted panel absorbers so please
share your experience as you go along. I for one am very interested.

I suggest you get yourself some testing software if you don't already have
something. Room EQ Wizard is good, and free. This way you'll be able to
see what your room is like and the effect your panels have on it.

Paul P

[Ethan Winer]

Originally Posted by TooManyToys

I've never seen 1/8" ply in HD.

You might have to go to a real lumber yard. But 1/8 inch plywood is definitely available. It's often called Luan, a type of wood.

--Ethan

[Ethan Winer]

Originally Posted by avare

If someone is interested, the three panel equations are in Sharpe, available here.

Interesting, though the math is over my head.

It seems that document deals mainly with isolation rather than tuned absorption.

--Ethan

[Pier]

Originally Posted by PaulP

I have a couple of questions :

What do you plan on achieving with your panel absorbers ? Ie, what problem
do you have now that you plan on solving with them ?

How do you know how many you'll need ?

I believe very few members here have attempted panel absorbers so please
share your experience as you go along. I for one am very interested.

I suggest you get yourself some testing software if you don't already have
something. Room EQ Wizard is good, and free. This way you'll be able to
see what your room is like and the effect your panels have on it.

Paul P

Well honestly I will build as many panels I can afford because I have some serious problems around 50Hz and 112Hz. Didn't use any FFT analyzer, just a sine generator and my ears.

I expect to have a room where I can compose without being annoyed by the bad sound, not do any final mix or recording.

I will do more serious analysis, but I ask myself wether knowing better how bad is the room will do any help.... I don't want to spend much money in acoustics, and I will only work for a few months in this improvised studio.

When I start the project I will create a new thread for posting pictures.

[Pier]

Originally Posted by Ethan Winer

You might have to go to a real lumber yard. But 1/8 inch plywood is definitely available. It's often called Luan, a type of wood.

--Ethan

Ethan, do you think having wood on the back of the panel against the wall will be problematic?

[PaulP]

Originally Posted by Pier

Ethan, do you think having wood on the back of the panel against the wall will be problematic?

See the following document for a discussion on back panels :

http://downloads.bbc.co.uk/rd/pubs/reports/1992-11.pdf

For a lot more info see : this thread.

The BBC have apparently given up on panel absorbers in favour of deep
open panels of light insulation for very low frequencies.

Paul P

[Ethan Winer]

Originally Posted by PaulP

The BBC have apparently given up on panel absorbers in favour of deep open panels of light insulation for very low frequencies.

Right, same here. The only place I recommend wood panel traps now is for large rooms with lots of bare wall area. That's the one place where an alternating system of low-bass and high-bass traps can really help, without taking a lot of space from the room.

--Ethan

[DanDan]

Pier, if your panel is mounted on the wall, you do not need a back on it. Just seal it to the wall. Please note also that the fibre filling is intended to dampen resonance in the cavity. It should not touch the front panel or membrane, which needs to be free to vibrate. If this is a temporary situation I believe you would be best advised to construct corner straddling traps with FRK or other membrane on them. Wrap them nicely so that you can use them either way round, i.e. membrane to ward the sound or toward the wall/gap behind. These will be light and easily used in your next location. Or you would easily sell or trade them with friends. Panel traps not so easy to handle, move, etc.
Corner Absorber DIY details at studiotips.com
DD

[avare]

Originally Posted by Ethan Winer

It seems that document deals mainly with isolation rather than tuned absorption.

Correct. The resonance frequencies are the same whether the panels are designed for absorption or isolation. Getting into acoustics, it is the same as gypsum walls absorbing low frequencies. The peak of absorption is at the MAM resonance frequency.

Andre

[Pier]

Originally Posted by DanDan

If this is a temporary situation I believe you would be best advised to construct corner straddling traps with FRK or other membrane on them. Wrap them nicely so that you can use them either way round, i.e. membrane to ward the sound or toward the wall/gap behind.

You mean some kind of triangular wooden prism with 703 inside?

Triangular prism - Wikipedia, the free encyclopedia

How big the corner thing should be to work on a 3.50 m width x 3.85 m long x 2.60m high room?

I liked the idea of flat panels around the room, they were cheaper and easier to do... also taking less space, and less intrusive.

The other option I was thinking of was making wooden frames with 4 or 6 inches of 703, covered with fabric like shaman did, but bigger and deeper. I don't know if those would be as efficient in bass frequencies as Ethan's design though...

shaman´s absorber build thread

The 4'' 703 has a nice absorption coefficient at 125Hz of .8 according to this table.

http://www.bobgolds.com/AbsorptionCoefficients.htm

What do you think?

Is the shaman broadband absorption panel completely useless for low frequencies like 50Hz?

Thanks for all your help

[Pier]

Originally Posted by Ethan Winer

Right, same here. The only place I recommend wood panel traps now is for large rooms with lots of bare wall area. That's the one place where an alternating system of low-bass and high-bass traps can really help, without taking a lot of space from the room.

--Ethan

But isn't your realtrap based on a sealed membrane absorption?

What would you recommend for a small room then?

[Ethan Winer]

Originally Posted by Pier

But isn't your realtrap based on a sealed membrane absorption?

No, our traps are based on high density rigid fiberglass, to which we add a thin plastic membrane. This enhances absorption at bass frequencies, but the basic principle of operation is still via "porous" absorption.

What would you recommend for a small room then?

The same thing - bass traps made from rigid fiberglass or mineral wool etc.

--Ethan