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Calculation for the slot width/slot depth for corner absorb.
Posted: Sun Oct 01, 2006 2:16 am
by stickers
The link for the calculation on john DIY wall units is dea. Does any one know the formula to figure out the slot gaps?
thanks
Re: Calculation for the slot width/slot depth for corner abs
Posted: Sun Oct 01, 2006 4:08 am
by rod gervais
stickers wrote:The link for the calculation on john DIY wall units is dea. Does any one know the formula to figure out the slot gaps?
thanks
There is no formula that I know of to calculate for a corner absorber.
The calculations I am familiar with are all for an equal depth Helmholtz absorber.
Perhaps someone else here is aware of one.
However - the formula for a standard Helmholtz absorber is:
f=2160 x sqrt (r/((d x D) x (r + w))
Where:
f = Resonant Frequency in Hertz (Hz)
r = Slot width
w = Slat width
d = The effective depth of slot (1.2 times the actual slat thickness)
D = The depth of box to the inside face of slat
2160 = c/ (2x pi) rounded
c = Speed of Sound in Inches/second
I hope this helped,
Rod
Posted: Sat Nov 04, 2006 3:00 pm
by orangenumerik
Hi Rod !
On page 181 of your book (awsome BTW) there is a graph with a broadband slot resonator said to handle frequency from 66.44hz to 155.82hz. How did you end up with these figures ? I've used the helmothz calculator (correted one) but i don't get to the same results at all. I 'd like to understand.
Thanks
Posted: Sat Nov 04, 2006 4:03 pm
by guitardad72
I 'd like to understand.
ME TOO!
Posted: Sun Nov 05, 2006 11:45 pm
by rod gervais
orangenumerik wrote:Hi Rod !
On page 181 of your book (awsome BTW) there is a graph with a broadband slot resonator said to handle frequency from 66.44hz to 155.82hz. How did you end up with these figures ? I've used the helmothz calculator (correted one) but i don't get to the same results at all. I 'd like to understand.
Orange,
First of all - as I noted above - there is no calculation (that I am aware of) for calculating Helmholtz Traps constructed at angles..........
The numbers reporeted for that were test results - not anything you could calculate.
I was just curious how it wold work - so built one and checked it out.
Thanks for the kind words BTY...........
Sincerely,
Rod
Posted: Wed Nov 08, 2006 2:16 pm
by orangenumerik
Rod
I was just curious how it wold work - so built one and checked it out.
This is far out news ! you actually built the thing and test it, with those results. No maths, just plain real world facts. You did an A/B i guess, can you post those numbers ? i'd really like to see the response curves before and after.
First of all - as I noted above - there is no calculation (that I am aware of) for calculating Helmholtz Traps constructed at angles..........
Yes i did read that, my understanding was that an angled slat resonator would just average the targeted frequencies. So can we say that when placing a slat resonator angled in a corner it will have a much lower absorption ratio versus air gap than a standard wall resonator ? And that the helmotz calculator is obviously not suitable for that particular application? Mainly due to the fact that
the resonator is place in a corner. Now the only way one could know the end results of such resonator is to built one and test it like you did. By logic if someone use your plan but puts a bigger air gap behind the resonator the trap should go lower. That is a think a semi-shot in the dark. But some sort of starting point...i guess.