[drhoon]

Hello,
I am trying to treat my small room (16 x 12 x 9) and noticed that l have problem 200 Hz below especially the 70 Hz peak.

I got an advice from GIK that having 6A alpha panels (3 of them) in the back will help with the room modes.

My question is "Am I sacrificing sub 100 Hz absorption performance for diffusion?"
From what I can gather 244 Monster Bass trap seems to do this better but kind of unsure if the added diffusion of Alpha offsets the Monster Trap's absorption ability overall.

Thanks and I linked my room REW data..(kind of new at this) http://imgur.com/v0oCPXb
Thanks

[Big Red Machine]

70 hz is probably the 8 foot room height. Is your room 8 foot high?

Are the 6A's = to 6 inches thick of absorbing material with the diffuser on the front surface? Then that sounds like the best of both worlds. Low frequencies will blow right through the diffusion plate and the low frequency benefit is from the 6 inches.

Overall, that is not a bad readout imo.

[drhoon]

70 hz is probably the 8 foot room height. Is your room 8 foot high?

Are the 6A's = to 6 inches thick of absorbing material with the diffuser on the front surface? Then that sounds like the best of both worlds. Low frequencies will blow right through the diffusion plate and the low frequency benefit is from the 6 inches.

Overall, that is not a bad readout imo.

I gotcha. I thought the diffusion plate would restrict the surface area to absorb low frequencies making it less effective but if it passes right through I guess it's not too much of a concern.

My room is 9 foot high because when I stack two 4' bass trap panels there is still about 5-8 inch space.

[Big Red Machine]

So this is an oversimplification, but for just an axial mode at 9 foot height:

freq = (1130 ft/sec)/9 ft x 2 runs (one up, one down) = 63 hz for a 9 ft ceiling

So look for multiples of 63 such as 126, 189, and even 31.5 for dips or peaks.  And then look at all the other room modes and see where they may overlap.

Axial Modes

The simplest path is the round trip between two opposing surfaces in the room. We can calculate the fundamental frequency for this effect using the formula:



 

Where F = frequency, W = wavelength, and c = the speed of sound.

 

If we want to calculate the effect of an 8 foot ceiling, the wavelength is 2H or 16 ft. (Remember, it's a round trip.)

The speed of sound is 1130 ft/second, so the fundamental of enhanced frequencies is 70hz.

Try Bob Gold's calculator, and then open a beer:
http://www.bobgolds.com/Mode/RoomModes.htm

[drhoon]

Thank you ill take a look at that.

My question has been answered through email with excellent GiK customer service by the way in the interim.

 

[poseidonsvoice]

Here is another one that's fun: http://amroc.andymel.eu/

Not for mobile devices. Use it on a desktop for the best experience.

Best,
Anand.

[Big Red Machine]

Here is another one that's fun: http://amroc.andymel.eu/

Not for mobile devices. Use it on a desktop for the best experience.

Best,
Anand.

Thanks! Very cool.

[youngho]

Does GIK offer the FlexRange membrane as an option for the 6A alpha panel?

[Glenn Kuras]

It seems as the other question was answered so..................................... ..............

Does GIK offer the FlexRange membrane as an option for the 6A alpha panel?

We could, but the plate has kind of the same effect as the limiter. It will reflect the upper frequencies. Actually not only reflect but also diffuse/scatter them. 

[youngho]

Hi Glenn, isn't the Flexrange membrane different from the scatter plate? The impression I got from this page (http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/) was that the membrane increased lower frequency absorption. Since the original poster had significant issues at 50-70 Hz, it seemed to me as though the addition of a membrane might increase absorption below 100 Hz (the 6A Alpha page does not show absorption data in this frequency range: http://www.gikacoustics.com/product/6a-alpha-panel-diffusor-absorber/).

Young-Ho

[Glenn Kuras]

Hi Glenn, isn't the Flexrange membrane different from the scatter plate? The impression I got from this page (http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/) was that the membrane increased lower frequency absorption. Since the original poster had significant issues at 50-70 Hz, it seemed to me as though the addition of a membrane might increase absorption below 100 Hz (the 6A Alpha page does not show absorption data in this frequency range: http://www.gikacoustics.com/product/6a-alpha-panel-diffusor-absorber/).

Young-Ho

There are 2 links on the test page that take you to the PDF of the Alpha that shows testing below 100hz. In a way you are right as the membrane does increase the low end a bit more then the plate, but the plate still is acting like a membrane which does help.