I'm putting together the HI-VI swans 3.1 DIY kit. They give you a bunch of regular flat 1.5'' foam to cut into pieces for the box. Would I be better with egg crate foam to help diffuse the sound waves inside the box better?? or should I just use the stuff they gave me ? 🙂
Different product. It is fibreglass or polyester or polypropylene fibre mixed with the PU foam in the sound panels Much more expensive stuff by a factor of 10.
interesting. So what do you guy stuff your speaker boxes with most of the time??? and why?
I was always under the impression that the conical protruding cones from the "egg crates" diffuse the unwanted/unneeded rear standing waves from the speaker and help in the equation of a much cleaner sounding speaker.
I was always under the impression that the conical protruding cones from the "egg crates" diffuse the unwanted/unneeded rear standing waves from the speaker and help in the equation of a much cleaner sounding speaker.
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The egg crate shape is good for obliquely incoming sound waves, in a loudspeaker box however, distance between source and damping is rather small so the impedance of the damping material is more important, that means typically a material of less density then you would use for room acoustics
For a given thickness, for low frequency damping it is better to not have the protrusions, because they decrease the already insufficient damping material thickness.
In loudspeakers it is possible to put damping material away from walls, where it is more effective. So it makes sense to concentrate on this instead of on the material on the walls.
In loudspeakers it is possible to put damping material away from walls, where it is more effective. So it makes sense to concentrate on this instead of on the material on the walls.
For very low frequency, the damping stuff is unnecessary. See a compact subwoofer with a 6-8" in 15/25 l closed box
Here are links to Auralex tiles of various profiles which should be very similar to other foam of similar density showing the absorption coefficient at various frequencies.
Auralex Acoustics | Total Sound Control
Auralex Acoustics | Total Sound Control
Auralex Acoustics | Total Sound Control
I find them very useful for ported boxes.
Auralex Acoustics | Total Sound Control
Auralex Acoustics | Total Sound Control
Auralex Acoustics | Total Sound Control
I find them very useful for ported boxes.
Better not to cut the foam into pieces, rather form a roll of it and put in the right place to suppress the depth and height resonance while at the same time providing a clear path from the woofer to the vent.
I am trying to improve my listening room and spent some time reading research papers and etc.
The crate design reduces the foam`s absorption, at least based on the tests I saw. Full thickness foam performs better compared to crate. The crate shape will not diffuse the soundwave as you expect because it doesn`t reflect much. To diffuse you need a hard non-absorbent panel of irregular shape (random patterns or similar). Out of about all present materials, with the exception of fiberglass, all will absorb very little below 500Hz. Fiberglass does absorb better but difference plotted on curves was marginal. The only thing that can help you with low bass notes, as it appears (and that to a some frequency limit) would be irregular shape of the chamber.
The crate design reduces the foam`s absorption, at least based on the tests I saw. Full thickness foam performs better compared to crate. The crate shape will not diffuse the soundwave as you expect because it doesn`t reflect much. To diffuse you need a hard non-absorbent panel of irregular shape (random patterns or similar). Out of about all present materials, with the exception of fiberglass, all will absorb very little below 500Hz. Fiberglass does absorb better but difference plotted on curves was marginal. The only thing that can help you with low bass notes, as it appears (and that to a some frequency limit) would be irregular shape of the chamber.
I've used the pink fiberglass insulation for the speakers I've built, and had very good results. You would want to avoid touching it though. Wear gloves or just wrap your hands in plastic shopping bags even. If you don't, the fiberglass fibers will make your hands itch pretty badly for awhile.
The other nice thing about it is that if you buy the paper-backed roll of it like I did, you can use it like a panel if you want on a ported build, or you can pull it off of the paper backing and use it as stuffing.
The other nice thing about it is that if you buy the paper-backed roll of it like I did, you can use it like a panel if you want on a ported build, or you can pull it off of the paper backing and use it as stuffing.
This is what happens when you listen to the experts, and not your common sense, and your measurement gear. Well, what can you do. Gotta save your energy for better cause.
You can use glass wool, which is an excellent material for stuffing enclosures (cheap, too), but with some serious precautions. Fragments of glass fibers floating in the air of your room are not good for your health. Ditto for driver's magnetic gap.
I have seen several vintage vented loudspeakers with glass wool stuffing wrapped in a cloth (thin one), like a pillow, glued to the internal walls of the enclosure.
Closed box - stuff the box with glass wool and lay a piece of cloth (large one, to cover the whole front panel) immediately behind the woofer, to protect magnetic gap.
TL enclosures - put a piece of cloth behind the woofer and another piece after stuffing, before the vent (not immediately on the vent).
I can recommend glass wool for TL and closed enclosures, but not for vented (bass-reflex) enclosures - it is much easier and faster to work with other materials.
I have seen several vintage vented loudspeakers with glass wool stuffing wrapped in a cloth (thin one), like a pillow, glued to the internal walls of the enclosure.
Closed box - stuff the box with glass wool and lay a piece of cloth (large one, to cover the whole front panel) immediately behind the woofer, to protect magnetic gap.
TL enclosures - put a piece of cloth behind the woofer and another piece after stuffing, before the vent (not immediately on the vent).
I can recommend glass wool for TL and closed enclosures, but not for vented (bass-reflex) enclosures - it is much easier and faster to work with other materials.
I've always stayed clear of using fiberglass. There have been alternatives to that nasty stuff for so long that I really cant understand why anyone would use it over Polyfill, Acousta-Stuff and wool.
I hadn't noticed any problems with the fiberglass, but that doesn't mean there aren't any. Might be time to switch to a new material...
Only that you should always wear gloves and a mask while working with it, should also have a thin layer of cloth over it so no fibres will get airborne and go places they should not.
Other than that I seem to recall some measurements where rockwool was deemed superior to fibreglass. I also seem to remember acousta-stuff came out a bit down the list.
Do not trust my memory though, I don't.
Edit:
Link to a thread discussing the topic:
https://www.diyaudio.com/forums/multi-way/215133-box-colourations-22.html#post3086482
Other than that I seem to recall some measurements where rockwool was deemed superior to fibreglass. I also seem to remember acousta-stuff came out a bit down the list.
Do not trust my memory though, I don't.
Edit:
Link to a thread discussing the topic:
https://www.diyaudio.com/forums/multi-way/215133-box-colourations-22.html#post3086482
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