ASC Tube Trap Question, Yes I searched first :)

[QuitteR]

Did you have any answers on this in the end? I'm also very interested in the efficiency of these traps under 100hz range and down to 50hz as this seems a problem area in my current room on basic equations.

Does the attack wall help at frequencies this low or is additional bass trapping needed in a small room?

Be interested in your thoughts.... Dave

[KennyS]

Originally Posted by QuitteR

Did you have any answers on this in the end? I'm also very interested in the efficiency of these traps under 100hz range and down to 50hz as this seems a problem area in my current room on basic equations.

Does the attack wall help at frequencies this low or is additional bass trapping needed in a small room?

Be interested in your thoughts.... Dave

Hey man I'm in the studio all day today but I will get back to you later today.

Cheers

[bwo]

Considering that ASC tube traps are pressure based, they need to be put where the pressure of the problem frequency is for them to be effective.

Personally I would rather buy pressure based traps from RPG, but that's me.
RPG Diffusor Systems, Inc.

[Ethan Winer]

^^^ Just to clarify, ASC Tube Traps are velocity absorbers, not pressure absorbers. They're made from 703 rigid fiberglass that's bent into a curved shape, so some of the material is spaced out from the corner to increase absorption at low frequencies. They do have a reflecting surface covering half of the curve, but that doesn't make them pressure-based.

--Ethan

The Acoustic Treatment Experts

[bwo]

Originally Posted by Ethan Winer

^^^ Just to clarify, ASC Tube Traps are velocity absorbers, not pressure absorbers. They're made from 703 rigid fiberglass that's bent into a curved shape, so some of the material is spaced out from the corner to increase absorption at low frequencies. They do have a reflecting surface covering half of the curve, but that doesn't make them pressure-based.

--Ethan

The Acoustic Treatment Experts

Are you 100% sure? I also believed that, but was corrected by a seller of ASC that said they are pressure based. He also states this in his advertisements (in norwegian):
Hifisentralen - ASC TubeTraps

[Ethan Winer]

Yes, I'm sure. I think the confusion might arise from the wording ASC uses in their descriptions:

ASC TubeTraps for Control Room and Mix Environments

You put bass traps in corners where "pressure" is higher, but they still act on velocity. I've seen the insides of tube traps and they are definitely not sealed, nor any sort of pressure absorbers.

--Ethan

[hsal]

from The ABCs of ASC's Tube Traps :

The Tube Trap is a fabric covered porous cylinder (comprised of 1" thick compressed fiberglass) that, when sealed, acts as a pressure zone device. Sound pressure building up around the outside of the hollow tube creates a pressure differential between the pressure inside and outside the tube. In an effort to eliminate this differential, the sound wave responsible for the pressure zone attempts to pressurize the hollow core of the tube. In order to do so, it must travel through the tube's resistive fiberglass which, in turn, dissipates the wave's energy as heat. Simple in design, relatively simple in execution and simply indispensable for improving the acoustics of your listening room

[Glenn Kuras]

Originally Posted by hsal

from The ABCs of ASC's Tube Traps :

This is right off the Tube Trap page.

Because the TubeTrap only reacts to sound pressure it is sometimes referred to as a pressure-zone bass trap. Although the TubeTrap is a broadband sound trap, it can be modified by adding additional acoustic circuitry to give it an enhanced narrow band range of sound absorption in addition to its broadband bass trap properties. However, this is not to be confused with a "tuned bass trap" which is exclusively a narrow band bass trap and has no broad band properties.

[hsal]

I think tuned in this setting reffers to it not being narrowband.

They clearly state that the difference in pressure contributes to the performance.

To me it seems like a hybrid, the resistive porous layer probably have bigger effect placed in positions with high particle velocity, and the pressure differantial
will enhance the performance, the main reason probably being that diffraction around the object without penetrating the material are reduced at lower frequensies.

[Ethan Winer]

Originally Posted by Glenn Kuras

This is right off the Tube Trap page.

Yes.

I once measured a pair of the largest 20-inch ASC tube traps in a lab, and it was very broadband and linear over the entire range of test frequencies. It behaved exactly as you'd expect from an absorber made from rigid fiberglass.

--Ethan

[bwo]

To me it also looks like a combination of pressure based and broadband.

[Glenn Kuras]

Originally Posted by bwo

To me it also looks like a combination of pressure based and broadband.

I actually have been working on a trap (I call it FRL) that use a combination of pressure and broadband. A tube trap really is basically a broad band with a limp membrane. Not that there is anything wrong with it, but it is what it is.

[KennyS]

Ok couple of things I have an entire Attack Wall that I use everyday in my studio. It is the single best purchase I have ever made for my studio even though it cost about half a API 1608. If anyone has any questions about the system feel free to let me know your specific questions.

It should be pointed out that ASC is working on their traps right now as well.

Cheers,
Kenny

[bwo]

I'm uncertain about the effect of ASC tube traps. Here's measurements from a room with and without ASC tube traps. The red is without and the blue is with four 20" tube traps and eight 16" ones. The room is quite big and has an opening to another room.
I'm having difficulties seeing the blue one properly on my screen, but if the measurments are correct the effect doesn't look very good. At least not below 200 Hz.

[Glenn Kuras]

I am not so sure those tests are correct. There is a lot of goofy stuff in them. First being that much ringing at 10hz??

[Mctwins]

I don't know how the room looks like or how the measurements been done, I don't see any difference between before and after. Still peaks and deeps.

[avare]

Originally Posted by KennyS

Ok couple of things I have an entire Attack Wall that I use everyday in my studio. It is the single best purchase I have ever made for my studio even though it cost about half a API 1608.

Yes, good acoustics can be incredibly inexpensive compared to other studio equipment. Too many people do not want to improve the sound of everything they record, as opposed to having one additional piece of hardware, that may affect as little as one channel/track/signal input.

Andre

[cporro]

i did a diy build about 6 years ago. i remember the instructions being to seal them. now, i don't how this works out in the real world. after all they are compressed fiberglass with one side of the foil cut off....doesn't sound air tight to me. but maybe they are nearly air tight. and shouldn't this be a continuum? with a little bit of a leak shouldn't you be able to build a bit of pressure inside? a hybrid of types?

i'm debating on building some more treatments for my studio. tube traps and something using mass loaded vinyl are 2 areas i'm looking at. my attraction to tubes is their potential for diffusing the sound a bit.

[Ethan Winer]

Originally Posted by cporro

i remember the instructions being to seal them. now, i don't how this works out in the real world. after all they are compressed fiberglass with one side of the foil cut off....doesn't sound air tight to me.

Exactly. Most of the DIY tube trap plans I've seen are a joke. There's nothing to seal!

--Ethan

[OpusOfTrolls]

From everything I have read, Tube Traps ARE a pressure based device. The speed of sound is slowed by the absorber, into the compliant air chamber where the pressure equalizes over the course of the half wave. That is why the larger traps absorb a lower frequency. It the the particle velocity from this pressure differential that does the absorption. There is no membrane, just an airtight porous absorber, if there was such a thing.

[cporro]

yeah, i remember the absorption data on the tubes relating to the tube diameter. and that kinda makes you feel like they are sealed. but you are also enforcing a larger air gap between the wall and the far side of the tube. and this should "tune" them a bit. like changing the airspace behind a panel. right? argggh! i give.

[MaximumAdams]

I've been somewhat interested in them myself, mainly for the "quick sound field" applications for tracking. They look like they'd make for "interesting" reflections for vocal or drum tracks perhaps, but from what I've seen there needs to be a heck of a lot of them to start being worthwhile in the control room. IMHO (and as unqualified as I may be to comment) in all of the promo photos of CR's that use the system to good effect there's usually a pretty big air gap created behind them. I'm thinking that maybe this could heavily increase their effectiveness in the lower frequencies. For all I know, you may achieve similar results by building yourself a cocoon of simpler free standing absorbers.
Maybe Ethan or Glenn might be able to share some insight on this?...

[MaximumAdams]

[MaximumAdams]

http://www.asc-studio-acoustics.com/sub-trap.htm
I have wondered if there could be some significant usage for these though...

[KennyS]

Ok I'm going to chime in here and answer some non-scientific questions. Because I haven't idea about why they work, I just know they work and I'm happy with that.

First off, I have 22 and the monitor tubes so 24. My entire control room is wrapped with them. They can be as close to the wall as you would like. I keep mine right up against the wall. Second, I have only used two to four tubes behind me while mixing on the fly and the mix translated very well. So no you don't need a full Attack Wall.

Any other questions, feel free to ask!

Cheers,
Kenny

[Ethan Winer]

Originally Posted by MaximumAdams

Maybe Ethan or Glenn might be able to share some insight on this?

I've noticed that Art Noxon (head of ASC) recently started posting here, so maybe PM him and ask him to chime in. He's definitely the expert with Tube Traps!

--Ethan

[MaximumAdams]

Thanks Ethan. Great idea.

[MaximumAdams]

Originally Posted by KennyS

Ok I'm going to chime in here and answer some non-scientific questions. Because I haven't idea about why they work, I just know they work and I'm happy with that.

First off, I have 22 and the monitor tubes so 24. My entire control room is wrapped with them. They can be as close to the wall as you would like. I keep mine right up against the wall. Second, I have only used two to four tubes behind me while mixing on the fly and the mix translated very well. So no you don't need a full Attack Wall.

Any other questions, feel free to ask!

Cheers,
Kenny

Well that answers the question about the air gap then!

[MaximumAdams]

Oh, just a thought..
Do they fit the description of a damped mass-spring somehow? Or does that fall under a pressure based design?