Need Feedback: Bass Trap Ceiling Module Concept

[ArcadeKO]

So with my space, full 2'x4'x4" panels along the ceiling corner are not exactly ideal. I have designed a modified Superchunk trap that uses 75% of the material of a full size panel with varying depth from 2" to 6" - These would be much easier to install but I am not positive of the effectiveness. Let me know what you think.

This concept shows the unwrapped trap. While the actual surface area of the trap is less than a full panel, I would be able to add more of these so effectively I would be covering more surface area by using additional modules.

[ArcadeKO]

Another possible method for filling using the basic superchunk stack method. However, this design uses 50% less material (eg 1 panel makes one trap, as opposed to 1.5 panels for the 3 layer fill, also creates less 6" and 4" depth area). Uses less panels which I would imagine directly affects the effectiveness of the trap - it also would take a lot more cutting of rockwool which I do not imagine will be that easy.

[ArcadeKO]

One more showing the panel mounted and notched for the trim.

[technocolour v2]

I'm far from an expert but I would assume that by saving 50% on a superchunk design you might as well make a straddling corner trap so you can maximise surface area and depth.

[ArcadeKO]

Originally Posted by technocolour v2

I'm far from an expert but I would assume that by saving 50% on a superchunk design you might as well make a straddling corner trap so you can maximise surface area and depth.

A straddling corner trap uses 2 sheets.
The first design (3 layers) uses 1.5 sheets (75%)
The second design (superchunk style) uses 1 sheet. (50%)

I am leaning towards the 3 layer design as it seems like it would be more effective.

I don't have room for 2'x4'x4" straddling traps - that is why I designed this alternative.

It seems to have enough material and surface area to be effective but I was hoping that someone with some acoustic expertise could let me know if there is any issue or flaw in my design.

[technocolour v2]

Originally Posted by ArcadeKO

I don't have room for 2'x4'x4" straddling traps - that is why I designed this alternative.

Ok, gotcha. I was wondering why the width was twice the height. On a completely different tangent, what software did you use to model the traps?

[ArcadeKO]

Originally Posted by technocolour v2

Ok, gotcha. I was wondering why the width was twice the height. On a completely different tangent, what software did you use to model the traps?

Google Sketchup

[DanDan]

It seems to have enough material and surface area to be effective but I was hoping that someone with some acoustic expertise could let me know if there is any issue or flaw in my design.

All good, no flaw. 6 inches is good. More would be better. Perhaps a light frame, lined with fabric, stuffed with light attic insulation, would be an easier build?
DD

[ArcadeKO]

Originally Posted by DanDan

All good, no flaw. 6 inches is good. More would be better. Perhaps a light frame, lined with fabric, stuffed with light attic insulation, would be an easier build?
DD

The Roxul is rated to absorb the bass frequencies. Wouldn't the light attic insulation be less effective?

[DanDan]

Strangely dense rockwool becomes reflective at LF when it gets thicker and or denser. Try playing around with an Absorption Calculator, e.g. Whealy, or Porous Absorber Calculator Note what happens with different thicknesses and Gas Flow Resistivity numbers. Common Gas Flow Resistivity numbers.
For your designs I would stick to 30-50KG stuff. Fibreglass will be easier to work with, lighter, more rigid.
If you were to go for the larger 34 inch wide SuperChunks or any other very deep design, I would push towards 15-30KG.
DD

[ArcadeKO]

Originally Posted by DanDan

Strangely dense rockwool becomes reflective at LF when it gets thicker and or denser. Try playing around with an Absorption Calculator, e.g. Whealy, or Porous Absorber Calculator Note what happens with different thicknesses and Gas Flow Resistivity numbers. Common Gas Flow Resistivity numbers.
For your designs I would stick to 30-50KG stuff. Fibreglass will be easier to work with, lighter, more rigid.
If you were to go for the larger 34 inch wide SuperChunks or any other very deep design, I would push towards 15-30KG.
DD

Thanks DD - I will try and play with that some - If you have a chance maybe you could check out my thread on mid-high freq and make a recommendation as to what treatment I could add?

Need help taming Mid ~ High Frequencies

[aackthpt]

If I get this correct, your first design is 16x8, and your second design is 18x6. These type devices depend mostly on size (depth) to reach very low so personally I'd pick the first for greater effectiveness. It also has greater total volume. Basically make it as large as you can in all dimensions. And if you can't make the 8" side any larger, remember the face could be curved or the thing could even be a sort of cube. Check out the GIK soffit trap for an example of taking it as far as possible given a fixed dimension in each direction.

DD already gave you the 'modify density based on depth' suggestion essentially, so you should be good there. If you can go to 12 inches or more each direction you are probably best off with fluffy fiberglass which is readily available and VERY inexpensive. Also you can readily put some with facing out while filling it with unfaced in order to limit its operation to LF a bit - highly convenient.

Cutting "rigid fiberglass" panels isn't said to be very difficult. I imagine an electric carving knife goes right through it, I've read that some make a pre-slice with a utility knife to guide the cut. Some cut it with shop tools, but I'd think that would throw a lot of fiberglass into the air unless you had a really good dust control system. There are some youtube vids of guys cutting it for superchunks if you want to see the methods of others.