[omholt]

I'm planning to build some basstraps. Probably triangle ones stacked with rockwool. Let's say I want them to be reflective of migh mids and the highest frequencies. What reflective material do I then use?

I would also like to know what different types of reflectives can do as to which frequencies they will effect.

 

[omholt]

FSK scrim will be similar as aluminium foil, right?

Is it possible to do something else to increase the absorption of low frequencies?

 

[omholt]

Thanks Bryan. This is great info.

A few more questions:

1. You're mentioning to strecth tight if I use plastic. Is that important? I just filled a couple of "pillows" with rockwool. I used some plastic bags from the grocery store around the rockwool, but didn't care about strecthing it tight.

2. For the tritrap; Will I loose any effectiveness when using some thin timber on the sides? I need to get some sturdiouness so I can move it around.

3. I see some are saying that for a tritrap and for best bassabsorption, it's an advantage that the material one is using is not too dense. That lower gas flow resistance will actually give a better result. Is that true? We don't have 703's here in Norway (to my knowledge), but there are different kinds of both fiberglass and rockwool.

 

[omholt]

For a typical sized triangular chunk absorber (17x17x24"), something around a 3lb density for fiberglass or 4lb density for mineral wool is usually optimal.

Bryan

Are we talking lb/ft3? Before I convert to metric, I need to know correct measures....

 

[omholt]

Thing takes time. But I'm getting there.
If I want to increase the absorption at low frequencies, is FSK the recommended material for a membrane? And how do I wrap it to get best result? Are using more layers in between better?

Is it also important then that the top and bottom are totally sealed?

 

[omholt]

Yes. I'm not planning on making a tuned Hemholtz resonator. I'm aiming for a broadband basstrap. Since I'm using absorbents that go all the way up in first reflections, I think it's ok that the these basstraps will reflect mid and high frequencies.

So, I guess what I'm asking is what material will give the highest hump and how to place it for maximum effectiveness. And how can I address different frequencies (by thickness)?

Someone indicated that sealing the top and bottom would increase bass absorption, but I don't know if that's correct.