Best bass trap insulation material - Australia

[Blueeyedfrog]

I've just finished building my first sub and after doing some sound measurements I have decided to make some corner bass traps. This is because I have a very uneven room response (see graph). For example, I have a big -22db dip at around 28hz or 40hz, depending upon listening position and/or sub placement.

I have examined this informative list of insulation material coefficients at: http://www.bobgolds.com/AbsorptionCoefficients.htm.

However, could people suggest the most suitable material that can be purchased in Australia?

At this stage it appears to be:

Brand: CRS Bradford - Rockwool
Product: Glasswool Anticon Roofing Blanket - R2.5 Thermofoil
Specs: 95mm thick & 0.72 at 125hz

Can anyone suggest a better alternative(s)?

I have also ordered a Behringer Feedback Destroyer.

I also would like some advice on bass trap placement. As the diagram shows, the room is a T shaped garage. It is also a laundry area. The room is made of concrete block. My car is positioned left. I have partitioned part of the garage off with a very light flat cotton curtain as shown. The corners are marked with the proposed trap positions with the exception of the bottom left corner which I may also put a half leangth trap above the laundry sink. Unfilled box shapes denote shelving areas (which could be rearranged). Sub far right, listening position in pink. Yes, there is a garage door behind the car.

I'd love to hear feedback/suggestions as to a different or better layout...

In addition to my above question re suitable insulation material, my biggest questions are:

a) should I place a trap as shown in the top left corner (is it worth it)?
b) how much does the car and light weight curtain change the room from a T into an L?
c) will the traps and/or BFD fix/improve my response?
d) are traps using triangle chunks filling the entire corner better than 4inch sheets fitted diagonally across the corner?

Cheers

[bpape]

Start with the sub in the corner and tweak seating for best response that way. Then, play with sub location to better things from there. Lastly, play with mains location (specifically distance to the wall behind them) to smooth things further.

The other null you're getting is likely off the middle of the wall behind the seating position. Consider some 6" panels there.

Bryan

[Blueeyedfrog]

From memory, the green line is with the sub in the corner and the LP as per the diagram. The purple line is the sub as per the diagram and the seating about 750mm (30") further back. It's really the seating position that made the most difference. I don't know if it makes any difference that the sub has two opposing PRs so one will have to face up close to a wall - is that ok?

Are you suggesting place the sub in the corner in front of a trap, or not? I haven't tried moving my mains much - they were in line with the centre speaker and facing forward but the way they are now sounds so much better for positioning (with one listener - worse for two side by side).

Your suggestion for the 6" panels on the rear wall (it does get very boomy the further one goes back) - is that in addition to placing corner bass traps or before installing the corner traps? Also, what dimensions would you suggest for the rear wall panel? I forgot to mention the ceiling height is 2.4m.

Many thanks.

[Blueeyedfrog]

I also have a budget question. It appears that having fully filled corners is better than flat panels across the corners with airspace behind. My budget can only stretch to doing either four traps with just a single panel or two traps filled right to the corners.

Which would be the better option given that I want to dampen the lowest frequencies (around 30hz)?

If two full corners are better than four unfilled, which two corners would be the best to start on?

Cheers,
Blue