[anobium]

Will this be an effective bass trap?  A soffit made out of Owens Corning 703 or 705 and installed at the wall ceiling interface? As an example if the soffit in the picture below was made with the 703 or 705. It could be built using a wood frame and covered with cloth.

Thoughts?




http://www.slatterysonline.com/gallery/displayimage.php?album=42&pos=2

[dnd]

This is my plan [ great minds think alike ].  I intend to make it somewhat tunable by making the verticle portion of the soffit removeable, like a speaker grill, to change what is inside the soffit.  I am even toying with the idea of putting a DYI arc tube trap inside some of it.

My room is multi-purpose, so I need to make any treatments "blend' as much as possible.

[Red Dragon Audio]

I think there would be room for improvement on that design but it would be a simple matter of using thicker pieces of 705 (not 703).

maybe use 2" or 4" or even thicker panels to build the soffits and pilars.

Thanks for providing the link as it's a really great idea.  Get's me thinking about my basement that I still need to finish...one of these days...

[klh]

I seem to recall from maybe a year or so ago reading that diagonal corner traps have the advantage of having greater efficiency of absorption over a broader frequency range because the distance of the fiberglass from the wall isn't constant (as opposed ot a soffit where the fiberglass is parallel to the wall and ceiling). As such, a soffit style bass absorber would probably be more efficient at essentially two peaks (determined by the distance from the horizontal fiberglass to the ceiling and by the distance from the vertical fiberglass to the wall) but have less of a "broadband-type" effect throughout the lower frequencies.

[Red Dragon Audio]

My gut feeling is that this type of rectangular soffit trap will still provide broadband coverage but I can't say if angled or "soffit style" is better as I haven't tested them.**

Here are a few reasons why I think the "soffit style" will still offer good broad band absorption:

• Very large amount of area is covered at critical corner points in room. (half of those pesky "right tri-corners" are covered).
• Additional layers of 705 are easy to add which will provide further bass absorption.
• Angle of wave impact still varies with angled traps like "soffit style".
• Panels of 705 placed parrallel with walls offer broad band absorption so this soffit style must as well.[/list:u]
  
  The soffit style does offer a good tradiational look.  On the other hand the angled soffit would be a clever design and would certainly stand out.  NathanM are you up for it?  maybe I should do it.  I am very close to finishing up my basement listening/theater room.
  
  
  
  **perhaps Ethan of Real Traps would like to comment; he has the field testing to back things up...I just have that cellulite enriched gut area to rely on

[MaxCast]

It would be interesting to see how a trap built up into the ceiling would work.  This would be for new construction of course but the bottom of the trap would actually be flush with the ceiling.  ONe could actually do two of them.  One for the wall too.

[MaxCast]

It would be interesting to see how a trap built up into the ceiling would work.  This would be for new construction of course but the bottom of the trap would actually be flush with the ceiling.  ONe could actually do two of them.  One for the wall too.

[dnd]

Ethan/Realtraps is now offering a pre-built soffit trap.

He also has plans for a membrane (with 1/8" hardboard...I think) trap that could go in a ceiling or wall and be flush with some pre-planning.

[Ethan Winer]

Max,

> It would be interesting to see how a trap built up into the ceiling would work. <

As Dave implied, if done right it can work really well.

--Ethan

[klh]

Please post your impressions and results with what ever you choose.

A soffit style bass trap would definitely look better and take up less wall space than a 2' x 4' x what ever thickness cross corner trap

Another thing to consider is pipe insulation cut in quarters of which the rigid fiberglass has a nominial diameter of 24" and is 6" thick. That would cover 18" of wall and 18" of ceiling and it would mount flush to both... it would also look good. Another thought... if it had FRK, then it would essentially be a diffusor as well.

Any thoughts on that?

[klh]

That pipe insulation with FRK cut in quarters might also be safer since the fiberglass would be kind of enclosed. Does anyone know if that is actually true? It seems logical, but I have no data to back it up.

[Red Dragon Audio]

Please post your impressions and results with what ever you choose.

 I hope you aren't asking me.  I talk quite a bit about finishing my basement but have yet to do it.  But seriously I am feeling like it's very close as we've cleaned the whole thing up almost completely.  We have hand picked what goes to garage sale, local donation center and the dump.  So we're pretty close to doing it.

A soffit style bass trap would definitely look better and take up less wall space than a 2' x 4' x what ever thickness cross corner trap

  Good points!

Another thing to consider is pipe insulation cut in quarters of which the rigid fiberglass has a nominial diameter of 24" and is 6" thick. That would cover 18" of wall and 18" of ceiling and it would mount flush to both... it would also look good. Another thought... if it had FRK, then it would essentially be a diffusor as well.  Any thoughts on that?

Here are my some drawings of my previous thoughts on cutting round pipe insulation:




Some of the pipes could be plain with no facing; perhaps at first reflection points to start with and other areas as well.  Then have the other pipes retain their FSK facing.  I know my local OC rep said you can get the pipe insulation in plain (no facing) or with the facing; the plain is cheaper.

My drawings don't address the ceiling at all though.

The other main issue with Pipe Insulation is that in the sizes over a few inches in diameter only come in densities of 3.00PCF-4.00PCF.  Owens Corning 705 is 6.00 PCF.  So you will need more of the Pipe insulation material to absorb as much as the 705.

FIBERGLASS SAFETY ISSUES:
Rigid Fiberglass is quite safe.  It's been glued, molded and pressed into a certain shape which is pretty innert .  Unlike the loose fluffy stuff, rigid fiberglass doesn't lose its fibers very easily unless it's being cut.  It's not going to jump out at you or anything.  So long as you are not cutting it, you will not experience any loose fibers floating around the room and you will be quite fine.

I have asthma so I am particular about the air I breath.  Having cut rigid fiberglass many times I have experienced zero problems other than itchy hands.  Just don't touch your eyes!    

[klh]

Sounds good.

I was thinking more along the lines of having the the pipe insulation only at the wall ceiling corner, and have it wrap around the room (much like a curved soffit). The benefit of the pipe insulation is one can have the FRK to increase bass absorption, but not worry about a reflection of  mid/high frequencies directly at the listener (as would be the case with flat rigid fiberglass with FRK). BTW, Knauf makes pipe insulation that is 6 " thick, has a density of 6 lbs/cf, has a foil face and a nominal diameter of 24". I would think that would be perfect for the wall to ceiling corner.

As for points of first reflection, 2" 2'x4' (OC703 or equivalent) unfaced panels spaced 2" off the wall would probably do just fine (and require no cutting!).

[klh]

Ethan... thanks for posting the link on the cotton thread. The waterfall plots make it very easy to make comparisons.

What do you think of using the Knauf piping (cut in quarters) as a soffit. I'm sure it won't perform as well as your SoffitTrap, but it sould perform nicely, and it would have a clean look. I like the fact that it only takes up 18" of wall and ceiling space, doesn't create a first reflection point, but actually diffuses mid/high frequencies, and is comprised of 6" thick, 6 lbs/cf density, foil faced rigid fiberglass. There is a local distributor, so I think I may do it. Do you see any drawbacks?

[Red Dragon Audio]

I was thinking more along the lines of having the the pipe insulation only at the wall ceiling corner, and have it wrap around the room (much like a curved soffit). ;

si si ... I knew you meant along the wall/ceiling boundaries as a curved soffit.  I was just being lazy by posting those drawings I had done for a previous http://www.audiocircle.com/index.php?topic=18278&start=0">post.

The FSK also makes it easy to paint to match the room.

BTW, Knauf makes pipe insulation that is 6" thick, has a density of 6 lbs/cf, has a foil face and a nominal diameter of 24".

Where did you find that this size of Knauf Pipe insulation is 6.00 PCF?  Just a few months ago Chad Kuykendall of Knauf sent me a PDF file with data stating that their larger diameter pipes are only 3.70PCF to 4.00PCF.  Here is the knauf 1000degree pipe insulation I am talking about.  Is there another type from Knauf? I hope you're right because that would mean it's only more effective at bass absorption.  

[Ethan Winer]

Krister,

> What do you think of using the Knauf piping (cut in quarters) as a soffit. <

Sure, if it's large enough it can only help.

--Ethan

[klh]

Thanks Ethan.