Bass Hangers

[mike0370]

Can any non professionals use these? or are they formula derived and only usable after extensive testing?

THey seem really interesting, especially since alot of people here use them,

I have read as many threads as 'hangers' would bring up. And there seems to be debate weather they even work?

thanks gentlemen

[mike0370]

Dug deaper... found answers... Looks like placement is either 1/2, 1/4, 1/8... room dimensions, while corners just go for 8" spacing usually....


as a side note, I coulda swore one of my acoustics books said that there was alot of testing and math invloved to get them to sway together.. but oooops cant find which one...



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[mike0370]

I dont know what the legalities are of quoting texts so moderators delete as needed ... but here it is... from

" Building a Recording Studio" by Jeff Cooper pg 47





"Another method for absorbing sound is called the broadband absorber. This method utilizes a series of hanging baffles to obstruct the travel of the sound waves. These baffles are constructed of porous materials, such as fiberglas (sometimes with a stiffer inner structure). When an approaching sound wave strikes the baffles, it is caused to diffract, thereby hitting other baffles in the immediate vicinity. The process repeats, eventually dissipating the sound energy of the wave.
In order for the broadband absorber system to work properly, the baffles must be hung in predetermined configurations. Each baffle must be spaced at a critical distance from the baffles surrounding it. The configuration and critical distance are determined mathematically and vary from one application to another. In general, the baffles must be spaced far enough apart to allow the sound waves of the appropriate frequency to enter, yet close enough to trap and absorb the energy once it enters.
Since the effectiveness of this type of system at low frequencies is a function of the size of the baffle itself, the dimensions of the baffle configuration can be adjusted or "tuned" to a desired cut-off frequency.
The baffle system is sometimes inappropriately called basstrapping. In actuality, the baffle system is a broadband absorber with a tunable, low-frequency cut-off."


I would love to hear Mr. Sayers and others advice/ comments about this ...

[Eric_Desart]

Mike,

Is there also math included in that Jeff Cooper's book?
Or is it just a nice text referring to mysterious math?

[mike0370]

No, no inclusion of the mysterious math rewuired for a hangers system

But, I have emailed Jeff Cooper this weekend to hopefully nail this down,

heres hoping I get a reply....

[Eric_Desart]

heres hoping I get a reply....

I hope you do too, because I'm as curious.

[John Sayers]

So am I Eric - I know of no Math on the subject. I do remember an article wayback in the 70s in a Recording Engineer magazine (REP) that covered it to a degree but in those days you couldn't right click save.

can you contribute any math to this?

I've observed oyster farms where there are oysters hanging in cages and a motorboat creates a wash and the oyster frames move with it and the wave from the boat is reduced significantly.

I'd appreciate your take on this.

cheers
john

[knightfly]

I've also seen harbors where a series of chains were intentionally suspended from another horizontal chains, such that the vertical chains hung down into the water; the sole purpose was to create a quiet water area behind the chain "filter" - It worked VERY well.

I've thought for some time that this is a similar phenomenon to bass hangers, but have seen no math either... Steve

[mike0370]

Well,

No sign of a reply.... Maybe one of the professionals on this thread would be intersted in contacting Mr. Cooper?


Everest cites a 1981 Michael Rettinger article in Recording E/P while discussing a bass trap I dont understand in Master Handbook. Perhaps thats the one you were thinking of?

Rettinger also wrote a couple books about acoustics that I might try to look into.