i'm planning on using many tube traps. at $200+ each, that can add
up. so i'd like to build my own. i found something on the web below.
i was wondering your thoughts. and before that, i'm going to put my
cheezy idea down and see if it flies with you guys:

my cheezy idea:
get a big pvc cylander (10" or 12" or 16" diameter) from a
construction store.
drill holes into it all over the place .5% or whatever the magic
number is
wrap and glue 1" owens corning 703 around it using spray adhesive
stuff the inside of the tube with regular owens corning fluffy wall
insulation
put "lids" on the ends (wood cutouts or whatever)
cover it with guillford of maine cloth
serve and enjoy

the idea of the holes is that any sound that passes through the 703
will then hit the holed-tube and act like a helmholtz resonator for
further bass trapping.

i don't even know if 703 could realistically be wrapped like that, or
if this design stinks for some reason.


here's what i found on the web:
Purchase a concrete forming tube (12 inches in diameter).

Make several slits with a utility knife to allow bass to pass through,
yet still reflect the highs.
hi guys,
Purchase a few yards of Gilford of Maine fabric FR 701.
(1-800-544-0200) This is what one of the major brands in traps uses.

Seal up the seam of an air-conditioner R-38 fiberglass insulation tube
with liquid nails.

Slide the fiberglass tube inside the concrete forming tube.

Cut some 3/4 MDF boards to form a circle to plug the two holes at the
end of the tube.

Glue some fiberglass to the the MDF plugs.

Glue the MDF plugs into the ends of the concrete forming tube with
liquid nails.

Cover the forms with the fabric and glue it on with fabric cement.

Place the full round tube traps in the corners behind the speakers to
help control bass resonances


see, i'm saving up $5000 to get a nice set of adams or equivalent, and
if i blow $3000 on traps, that's going to take me that much longer to
get my speakers. so i'd really appreciate any advice. i'm really
good with my hands, i have tools and access to a machine shop, and i
have pockets of time to do this.

I'm thinking of trying this technique when I get a chance and some spare
change.

http://ic.net/%7Ejtgale/diy2.htm

Looks like far less work. Not *exactly* sure how well these things will
work though. I figure though, for the amount of money and work
required, it's worth a shot.

Greg

X and Greg,

There's nothing magical about a tube shape. And there's no way a tube made
of rigid fiberglass will be a Helmholtz resonator. That requires a rigid
enclosure.

If you want to build your own bass traps, simply place rigid fiberglass
panels across the corners, including the wall/ceiling corners. If you use
2-inch rigid fiberglass you'll get good results. If you make them four
inches they'll work even better. Even if you decide to use round fiberglass,
there's no reason to build end caps and seal the traps air tight. I mean,
you can't seal fiberglass because it's porous!

--Ethan

Thanks for your response, Mr. Winer.

The reason I'm really into the tube idea is for the idea of an ASC
tube trap, along the lines of a "polycylindrical absorber". I'm
planning on setting up the equivalent of an "Attack wall" or "quick
sound field" to use ASC wording.

So let's say you need diffusion and absorbtion around the primary
listening position. the cylander will do two things: if it absorbs
any of the sound hitting it, then it's helping with absorption. if
it's reflecting any of the sound, the sound scatters in all directions
because it's round, so you get diffusion.

so you get two functions in one device. and i can't see how it would
really "fail". because if it stinks at absorbtion it's still
scattering the sound all over the place so you're getting diffusion.
or if it absorbs a lot that's good too. or if it's a mixture of
absorbtion and diffusion that's good too.

i think ASC makes tubes that have different absorbtion/diffusion
characteristics. like one side is reflective, the other more
absorbtive. that's really cool, because you can just spin them around
until your listening area has the right response. kind of like tuning
in a radio dial.

of course you have to like or at least tolerate the look of lots of
cyllader-shaped things all over the place. i think i could have some
fun with the aesthetics of it.

i'm sure in the end i'll kick down and buy some of those skyline
primitive root diffusors to put overhead. but i'd really like to
build the polycylindricals myself so i can put that saved money
towards a set of monitors.

Thanks for the link on this. I remember seeing this somewhere, but
couldn't find it. i'm going to bookmark it right now.

X,

if it's reflecting any of the sound, the sound scatters in all directions
because it's round, so you get diffusion.

A half-round tube is not really a diffusor. I think you should separate out
the two tasks, and build different devices that work best for each goal. A
tube made of squished fiberglass is not a very good bass trap, and half a
tube made of cardboard or plastic is not a great diffusor. This is not meant
to discourage you from experimenting! But don't expect much from a design
like that.

--Ethan

But isn't that what ASC tube traps are all about?

I'm still pretty stupid at this, but I've learned that sound can do
three things:
1)reflect
2)absorb
3)re-radiate

so if you're looking for a basic mixture of absorbtion and diffusion,
i don't see how it could fail. anything that gets absorbed by the
tube counts as working towards the absorption goals. and anything
that "fails" to get absorbed will in fact get reflected in a multitude
of angles because the sound hits the tube at different vectors. so
you get a scattering of the soundwaves. not along the lines of a qrd
or primitive root, but it's still way better than hitting a naked
drywall.

don't get me wrong, i plan to trap the corners, put up 703 panels, buy
some diffusors. but i'm planning to surround the mix area with tall
tubes, just like how they show on the ASC site. I just want to build
these myself since i will need a lot. I'll have to buy the primitive
root stuff, i'm just not that smart. but i should be able to build a
tube! it can't be *that* hard.... or can it? (cue suspense music)

like this:

http://www.asc-studio-acoustics.com/surround.htm


i wouldn't necessarily pseudio-soffit the speakers, but that's the
idea.
here's another cool one from their site (scroll down a bit and look
for the brown colored room with the pointed speakers):

http://www.asc-hifi.com/

xy,

But isn't that what ASC tube traps are all about?

First, understand that I'm biased because I sell acoustic treatment too, so
take what I say with a grain of salt. :-) That said...

I'll try again worded differently: Tube traps are not great bass traps
unless they're REALLY large, and the half round deflector on one side is not
a real diffusor.

Also, I don't see the value in surrounding a mix setup with any type of
nearby treatment - either absorption or diffusion. Maybe it's useful if you
do remotes and often have to create an impromptu mix station in a concert
hall's bathroom. But for a normal permanent installation, treatment should
be on the walls where the damaging reflections originate.

so if you're looking for a basic mixture of absorbtion and diffusion, i
don't see how it could fail.

Fail is too strong a word. "Not great" is probably more like it.

not along the lines of a qrd or primitive root, but it's still way better
than hitting a naked drywall.

Agreed. So why not just put the half-tubes on the walls where they belong?

--Ethan

XY wrote

like this:

http://www.asc-studio-acoustics.com/surround.htm

Hmmmm..I don't know about laying Genelec's on there sides.

Raymond wrote:
XY wrote

like this:

http://www.asc-studio-acoustics.com/surround.htm

Hmmmm..I don't know about laying Genelec's on there sides.


Why not? They'll sound different with the different dispersion pattern,
but in some rooms that might be a big deal.

Note also that the dispersion patterns on the 1030, 1032, and S30 are
all pretty different.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

This "trap" is supposedly more effective than the pipe insul one, but
a lot more work to build.
http://www.geocities.com/jonrisch/basstrap.htm

The pipe insul is easy to cut in half for wall mounted half rounds.
I mounted these to masonite and stuffed with more insul. I also put a
few strips of packing tape around the face for partial hf diffusion.
For diffusion though, a flatter (Polycylindrical) radius is better
that a half circle.

xy wrote:
i'm planning on using many tube traps. at $200+ each, that can add
up. so i'd like to build my own. i found something on the web below.
i was wondering your thoughts. and before that, i'm going to put my
cheezy idea down and see if it flies with you guys:

my cheezy idea:
get a big pvc cylander (10" or 12" or 16" diameter) from a
construction store.
drill holes into it all over the place .5% or whatever the magic
number is
wrap and glue 1" owens corning 703 around it using spray adhesive
stuff the inside of the tube with regular owens corning fluffy wall
insulation
put "lids" on the ends (wood cutouts or whatever)
cover it with guillford of maine cloth
serve and enjoy

the idea of the holes is that any sound that passes through the 703
will then hit the holed-tube and act like a helmholtz resonator for
further bass trapping.

i don't even know if 703 could realistically be wrapped like that, or
if this design stinks for some reason.


here's what i found on the web:
Purchase a concrete forming tube (12 inches in diameter).

Make several slits with a utility knife to allow bass to pass through,
yet still reflect the highs.
hi guys,
Purchase a few yards of Gilford of Maine fabric FR 701.
(1-800-544-0200) This is what one of the major brands in traps uses.

Seal up the seam of an air-conditioner R-38 fiberglass insulation tube
with liquid nails.

Slide the fiberglass tube inside the concrete forming tube.

Cut some 3/4 MDF boards to form a circle to plug the two holes at the
end of the tube.

Glue some fiberglass to the the MDF plugs.

Glue the MDF plugs into the ends of the concrete forming tube with
liquid nails.

Cover the forms with the fabric and glue it on with fabric cement.

Place the full round tube traps in the corners behind the speakers to
help control bass resonances


see, i'm saving up $5000 to get a nice set of adams or equivalent, and
if i blow $3000 on traps, that's going to take me that much longer to
get my speakers. so i'd really appreciate any advice. i'm really
good with my hands, i have tools and access to a machine shop, and i
have pockets of time to do this.

"Bryson" wrote
This "trap" is supposedly more effective than the pipe insul one, but
a lot more work to build.
http://www.geocities.com/jonrisch/basstrap.htm

Why would this be more effective? The only difference I can see is that in
those photo's he used what looks like domestic fibreglass. The only thing
which will make a difference is the mass of the fibreglass. The pipe
insulation that I used had a similar density to Owens Corning 703. Domestic
fibreglass is much less dense and is therefore much less effective.

--
Anthony Gosnell

to reply remove nospam.

Bryson,

This "trap" is supposedly more effective than the pipe insul one, but a
lot more work to build.

The key word is "supposedly." Again, there's no magic to a round shape, and
a plain old flat panel of rigid fiberglass placed across a corner will
surpass any of those tube designs. And with a lot less effort.

--Ethan

(xy) wrote in message . com...
...
The reason I'm really into the tube idea is for the idea of an ASC
tube trap, along the lines of a "polycylindrical absorber". ...

So let's say you need diffusion and absorbtion around the primary
listening position. ...
...
of course you have to like or at least tolerate the look of lots of
cyllader-shaped things all over the place. i think i could have some
fun with the aesthetics of it.
...

These look easy enough to make, if you prefer the flat aesthetic --
just some hardboard, fiberglass board, and a drill -- and I'd bet they
would work better as well:

http://www.rpginc.com/products/badpanel/index.htm

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Bryson,

This "trap" is supposedly more effective than the pipe insul one, but a
lot more work to build.

The key word is "supposedly." Again, there's no magic to a round shape, and
a plain old flat panel of rigid fiberglass placed across a corner will
surpass any of those tube designs. And with a lot less effort.

--Ethan

Ethan,

Have you EVER seen a comparative measurement, for both mounted/set in
a corner (comparing apples with apples) supporting that statement??

Eric

Eric,

Have you EVER seen a comparative measurement, for both mounted/set in a
corner (comparing apples with apples) supporting that statement??

As a matter of fact I have. When Doug and I brought our MiniTraps to IBM for
official testing, we also tested some 20-inch tube traps Doug had bought
years ago. I was always suspicious of ASC's claims - especially for their
absorption at very low frequencies - so we paid to test them! Maybe you
remember when I posted a scan of the actual printout from IBM on the
RealTraps site at your urging? At that time I mentioned a few columns that
were blanked out. One of those columns was the data for tube traps. I'll let
you guess what data the other blank column contained! :-)

If you've ever compared ASC tube traps to flat rigid fiberglass panels, I'd
love to hear about it.

Thanks.

Eric,

you confuse your believes with science ... If you compared apples with
apples (not your standard approach)

Why do you continue to insult me? I never insult you. If you have nothing to
contribute except the perpetual promise of future information, please keep
your insults to yourself. Thanks.

--Ethan

Eric,

No need to play the victim.

And you have no need to insult me. Truce, okay? Thanks.

So this means you know measurements of rigid fiberglass accross a corner
and tubetraps put in corners. You state as a fact that the flat panel
surpass any tube design.

Well, obviously it depends on the size and thickness of the flat panel,
versus the diameter of the tube and amount of fiberglass it contains. The
problem (for ASC) is they use only one inch thick 703 in the traps I've seen
and measured. So they're already at a disadvantage, though since the tube
wraps around there are essentially two panels with a built-in air gap. I'm
sure someone could make a tube shaped trap that's as good as a flat panel,
but I assume it would end up with about the same amount of fiberglass to
obtain similar results.

Until now, you answered that there is somewhere a blanked empty column.

Maybe I posted that somewhere else. I forget now, sorry. But I do have the
measurements IBM made right here, and I can tell you for certain they did
not test as well as a MiniTrap. Even more amazing is that size tube trap
sells for $780, versus $180 for a MiniTrap. But I concede that ASC tube
traps do look very nice. :-)

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...

Well, obviously it depends on the size and thickness of the flat panel,
versus the diameter of the tube and amount of fiberglass it contains. The
problem (for ASC) is they use only one inch thick 703 in the traps I've seen
and measured. So they're already at a disadvantage, though since the tube
wraps around there are essentially two panels with a built-in air gap. I'm
sure someone could make a tube shaped trap that's as good as a flat panel,
but I assume it would end up with about the same amount of fiberglass to
obtain similar results.

Maybe I posted that somewhere else. I forget now, sorry. But I do have the
measurements IBM made right here, and I can tell you for certain they did
not test as well as a MiniTrap. Even more amazing is that size tube trap
sells for $780, versus $180 for a MiniTrap. But I concede that ASC tube
traps do look very nice. :-)

--Ethan

Ethan,

I do agee that ASC are expensive things (not suitable for DIYers),
And while lots of people assume they are patented, only the additional
idea of the foil coverage is patented.
One can't patent the tube trap in itself because this patent is only
an extension of a patent of tubular absorber dated and expired BEFORE
the ASC patent. So my strict personal believe is that this additional
foil is mainly added in order to be able to patent the idea.
But still it indeed works as diffuser.

1) But now you compare with MiniTraps, not with plain old rigid
fiberglass.
2) And it was not about ASC (and price comparisons) but the principle
of tubular designs.
3) I'm also wondering if you are only comparing this 100 Hz MiniTraps
peak.
4) If the tube traps measurements are really put close in the corner,
then you should help a lot of people by showing this measurement.
5) If they tell what you say they tell than it can only support your
business.
6) But exact description of how they are measured are needed.
(position in room, how many, exact description or type of absorber
etc.)

So I don't see a reason to not show this measurement.

Eric

Eric,

I don't see a reason to not show this measurement.

Well I sure do! The tests we paid for at IBM had very different results than
what ASC publishes. But I don't think it's appropriate for me to publicly
question another company's products, whether justified or not.

--Ethan

"Greg" wrote
These look easy enough to make, if you prefer the flat aesthetic --
just some hardboard, fiberglass board, and a drill -- and I'd bet they
would work better as well:

http://www.rpginc.com/products/badpanel/index.htm

Just get the fibreglass with the foil on it and cut out squares of the foil
with a knife.

--
Anthony Gosnell

to reply remove nospam.

Eric,

So you don't do anything wrong by showing an official measurement that is
correct.

I realize, but I'm not comfortable doing that so I won't. Also, our tests
were for only two samples because that's all we had. But to truly know the
data is correct we'd need at least 4 or 8 of them (not sure because of the
tube shape).

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...


If you want to build your own bass traps, simply place rigid fiberglass
panels across the corners, including the wall/ceiling corners. If you use
2-inch rigid fiberglass you'll get good results. If you make them four
inches they'll work even better. Even if you decide to use round fiberglass,
there's no reason to build end caps and seal the traps air tight. I mean,
you can't seal fiberglass because it's porous!

Hi Ethan,

Do you have some pictures of how to place the panels across the wall?

Anybody else who did this? Sounds interesting ..

cheers,
bernd

Do you have some pictures of how to place the panels across the wall?

Anybody else who did this? Sounds interesting .. BRBR


OC 703 (the rigid fiberglass panels) is probably the most widely used
absorptive material in studio construction. When you see a cloth-covered wall
or panel in a studio, chances are good there's 703 beind it. A common use is
to make a wooden frame with fabric stretched across the front and 703 inside
it. Make sure to use fire retardant fabric if you're in a commercial space.
4" works well. 4" suspended a few inches from the wall is even better.


Joe Egan
EMP
Colchester, VT
www.eganmedia.com

Bernd,

Joe gave you some good suggestions, and you can read more in the Acoustics
FAQ, second in the list on my Articles page:

www.ethanwiner.com/articles.html

--Ethan