Broadband CORNER ABSORBER questions.

[robbielong]

Hi,

Basically this is what I'm hoping to build;
http://www.johnlsayers.com/HR/index1.htm

Questions:

- is it better to use the same size slats? Or mix them up - if the goal is 'broadband' absorbtion?

- I have some timber (lightweight Oregon) - that is only 18mm thick, by approx. 150mm wide (6inches) - is this a little thin for slats? Will the tend to resonate, even though insulation is glued hard up against them inside?

- I've used the Helmholtz calculator arriving at this:

Slot width. 5mm
Slat width. 150mm
Depth from wall. 400mm
Slat Depth. 18mm
Effective depth of Slot 21.6mm

Absorption Frequency. 106 hz

It will be 2.3metre high (7.5 feet)

Now that's all well & good for a flat wall panel, but its surely more complex for a corner? As you can see, 'depth from wall' is 400mm (just over a foot) - but of course, its a triangle, so depth from walls is variable, from nothing up to approx 400mm. Will this lower the centre freq a little? Any way of calculating this more accurately?

- How accurate do I need this anyway? I;m not chasing a specific freq at this point - just want to get some nice reflections off the timber, whilst attenuating from around 50 to 200 hz.

- it will be big & heavy on its own - but will it need to be fixed to the walls as well?

- John's design shows two 'layers' of insulation, with air gaps between - I assume this gap is to improve airflow and 'catch' the waves as the pass through? Is this preferable to filling the whole cavity with insulation? (as if a stack of triangular pieces of insulation).



Appreciate any help!

Thanks
Rob

[BriHar]

If the goal is broadband which it should be for the corners, then I would say just go for superchunk. If you need to reflect some highs, then just put thin plastic foil over the insulation under the fabric (doesn't have to be the entire surface). Use the slats more on the wall treatments.

[robbielong]

Hmm yeh - well I took the corner slat approach following John's advice drawing. It's built already! But haven't had a chance to test it. See how it goes. Other corners remain untreated at this point. Early days....