Filling for T'Fusor & MiniFusor

[Rev. Robb]

What are some of the common materials used to fill these products?

Methods & advise?

[Rev. Robb]

Not that anyone cares but I decided to use Great Stuff foam insulation to fill my T'Fusors. Works great!

Spray Foam Insulation | GREAT STUFF? Insulating Foam Sealant

[brandoncross]

It's a little too late but an acoustician friend of mine recommended the t-fuser to me and said to fill it with 703.
Best

[localhost127]

shouldn't the mfg provide the recommendation?

[boggy]

Originally Posted by localhost127

shouldn't the mfg provide the recommendation?

Good question!!!

Cheers

[NLP]

Originally Posted by brandoncross

It's a little too late but an acoustician friend of mine recommended the t-fuser to me and said to fill it with 703.
Best

Yes, this foam is closed cell type, in acoustics we use open cell foam or wool/ fiber materials.

[hsal]

It is not neciecerarly wrong to use close cell, depends on the goal.

Close cell will lower the absorption of the scattering device

[NLP]

Close cells materials are also a resonators.
Another question is how is this audible in practice.

[hsal]

close cell expanding foam will lower the resonance of a structure with thin abs plastic, it will have more mass and require more energy to resonate.

[NLP]

Also the open cell will do same thing but will not resonate.
But like I said: " Another question is how is this audible in practice. "

[hsal]

Another question is how is this audible in practice.

It depends on the surface area being covered, another point with filling the cavity, is that it can make the surface more reflective for lower mids, that might otherwise go thru the thin plastic.

[hsal]

Also the open cell will do same thing but will not resonate.

It will dampen the shell, but in the process add absoprtion.

as said, the effect depends on surface area covered, cut-of frequensy for sound that are not reflected (that go thru and will be reflected by the wall behind).

the goal dictates the sollution (close/open cell foam)

[NLP]

Yes I agree.
A few diffusers filled that way are not a problem but large surfaces will be.

[hsal]

Yes I agree.
A few diffusers filled that way are not a problem but large surfaces will be.

I don`t think there is a definitive rule of thumb, it depends on the nature of the room.

[hsal]

I think I misunderstood this

Yes I agree.
A few diffusers filled that way are not a problem but large surfaces will be. Yes I agree.
A few diffusers filled that way are not a problem but large surfaces will be.

Close cell will lower absorption, if one wants lower absorption the effect will be even more noticable (benificial ) when larger areas are covered and the cavity filled with closed cell foam.

[NLP]

Yes also that... otherwise try, experiment with closed cell foam if you do not believe.

[hsal]

I have.

[NLP]

Fine.
So closed cell foam is better in acoustics than open cell and fibre materials.

[hsal]

No it depends on the nature of the
room, and the use.

There are many skyline diffusors made by solid blocks (cut out) of close cell foam with a density similar to expanding foam.

[NLP]

Yes I know about EPS diffusors.
This is a budget solution and acoustics compromise.:(

[johndykstra]

who's on first?

[hsal]

eps is not an acoustic compromise

do a search

[NLP]

Fine
Consult with skilled acoustician.

[hsal]

Edit

NLP, can you give me the reason for it being an acoustic compromise?

[NLP]

For closed cell foam and EPS and XPS is no place in acoustics thats all in briefly.

[hsal]

skyline is consructed by acousticans
and Jens Eklund on this forum (acoustican) has constructed a diffusor out of eps

I`ll call it a day

good night

[NLP]

Yes and?!
This is budget solution.
Bye and do not believe a hype.

[johndykstra]

Originally Posted by NLP

For closed cell foam and EPS and XPS is no place in acoustics thats all in briefly.

It has no absorptive properties. That doesn't mean it isn't useful or a compromise. Sometimes it's the exact right thing. Sometimes it's useless.

[NLP]

Yes...
Try an extreme experiment: isolate the room inside with EPS... for heat insulation point of view is ok but for inner acosutics is not a desired thing.

If you fill a "diffusor mask" with closed cell foam is not such a big thing ok... but a large uncovered EPS surfaces are not OK.

[Jens Eklund]

EPS is an utterly useless material in regards to acoustic isolation or treatment except diffuser construction, since it is light and reflective:

http://www.gearslutz.com/board/6732069-post5.html

especially if painted. The only real downside of EPS (if used for diffusers) is the lower durability compared to wood or steal but the price difference is gigantic.


/Jens Eklund