Why do people prefer fiberglass over mdf and vice-versa? is it a sound quality thing or something?
Yeah it is a sound quality thing. MDF is a much stiffer, denser material and provides superior sound quality. Fiberglass is great for custom installs and pretty looks. A mixture of the two and you could have a great sounding, awesome looking enclosure. Pretty much any large flat areas of the enclosure you want to make out of MDF or HDF and curved or small surfaces use fiberglass.
it doesn't affect the SQ...wtf.
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Ok let me clarify a little here. It affects SQ because... enclosure flexing = loss of output, and that loss of output will not be equal at all frequencies. Still though an enclosure made
properly out of either mdf or fiberglass will sound good, with the mdf one sounding a little better/louder (when braced properly) because of less enclosure flexing. This all depends on how many layers of glass you would use as well. 10+ layers and I would say it would be competitively stiff, but it would cost a lot too.
Skyler Prahl wrote:Ok let me clarify a little here. It affects SQ because... enclosure flexing = loss of output, and that loss of output will not be equal at all frequencies. Still though an enclosure made properly out of either mdf or fiberglass will sound good, with the mdf one sounding a little better/louder (when braced properly) because of less enclosure flexing. This all depends on how many layers of glass you would use as well. 10+ layers and I would say it would be competitively stiff, but it would cost a lot too.
alright..i'm staying out of this one. my thoughts were posted.
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Offical dealer for the following-
SOUNDSTREAM
DB LINK
DB DRIVE
PANASONIC
GARMIN
ROSEN
SCOSCHE
XE DESIGNS
SOUNDGATE
PAC
LITEGLOW
^ .. im interested to hear wut u have to say...
if u want PM me
I agree with Skylar. Fibreglass resonates and colours the sound, hence affecting SQ.
you snooze you lose!
keep working, millions on welfare depend on you!
i know alot of people that use fiber glass in there sq and spl set up so they can round the edge's in the box and make a smouther path way for the air flow.
its up to the person if you want something to look nice use fiber glass, or a mdf base with a fiber glass face.
around 1/4" of a curve fiberglass surface is equal to roughly a 3/4" piece of mdf. that is half the reason people use fiberglass is the fact that you can use allot thinner piece to get the same strength of mdf. the other half is you can make shapes that mdf just can't get into. if you build your enclosure properly its not going to resonate, this doesnt even get into the fact that if the surface behind your subwoofer is curved, like a ball, you will pretty much get rid of any standing waves in the enclosure giving a better sound. its like saying wich is heavier a 2000 pound car or 2000 pounds of feahters.
http://www.flickr.com/photos/sndsgood/ https://www.facebook.com/#!/Square1Photography
If you dampin the enclosure, standing waves arent an issue.
you snooze you lose!
keep working, millions on welfare depend on you!
The shape of the box does more to reduce standing waves than anything else (ie cubic enclosures are worse than odd-shaped enclosures). The only enclosures that truly benefit from any kind of "dampening" (ie polyfill etc) are sealed. It's been shown many times that polyfill does little to increase efficiency, or reduce standing waves, in ported enclosures (it appears to be much more complicated with ported enclosures, and polyfill can impede air flow through ports which can reduce SPL and muddy up the sound). With ported enclosures, bracing and smoothing out airflow (curving corners, etc) does far more to increase SPL and reduce bass coloration than anything else - but it all depends on the individual install. It is very true that fibreglass truly shines in curved surfaces, but if done properly you should not have any issues with resonation or flexing. If you don't brace your enclosure, and it isn't made of concrete, you're asking for trouble.
The main benefits of using fibreglass over MDF are:
(1) fibreglass can be molded into whatever shape you desire - great for custom goodies, but time consuming.
(2) fibreglass of equal strength with MDF is much thinner and can be quite a bit lighter. This could be critical for tiny speaker pods where every cubic inch counts with regards to speaker response.
The main benefits of using MDF:
(1)Cheaper and easier to use than fibreglass
(2) Materials easy to find and work with (no airmasks, no days lost to sanding etc). If you screw up, or want to change something, it's easy to replace a panel.
(3) Flat panels made of MDF (unbraced) *typically* flex less than fibreglass. It's really easy to double up your board thickness to gain strength (provided that you have the room to do so). This argument is null if the fibreglass enclosure is properly braced and thick enough. Installation is the key thing here.
I agree with Sndsgood - you're really comparing apples to apples. If done properly there should be no discernable difference between speaker pods/enclosures made entirely from fibreglass or MDF. They both have their places in custom stereo installations.
The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.
I can help you with that one Brad... a subwoofer creates pressure, ranging from a little to a lot. In competition the pressure is so much that it can cause the enclosure to "flex". This flexing is what they are referring to above and thats something you don't really want. So inside the box you can run boards, almost like support beems to make sure the enclosure is solid.
Bracing has nothing really to do with how its "fastened" to the car, as much as it is making the box solid as a rock.
Feel free to correct my respone if I am wrong.
You're dead-on, Steve - the bracing we mentioned refers to internally bracing the sub enclosure to keep the walls from flexing at high volumes. Large, flat panels are the most prone to flexing/resonating, so braces (MDF, metal etc) are are used to make the box as solid as possible. Bracing can range from triangular pieces of MDF that you screw/glue to tie the sides of the box with the top and bottom, to pieces of wood that go the full width/height/depth of the box. The biggest consideration when bracing your enclosure is that the bracing material (along with subwoofer and port displacement) must be taken into account when determining net enclosure volumes and box tuning.
I've seen quite a few SPL-oriented guys use threaded rod for bracing (rods go full length/width/height and are bolted, with washers, both inside and out so that the enclosure walls can't flex in or out). It's fairly hardcore IMO, and I'm not sure how practical that would be for smaller enclosures but the SPL guys I spoke to swear by it. You don't have to worry about glue or screws coming loose, and the small diameter of the threaded rod takes up very little internal space and doesn't contribute to air turbulence which can affect SPL scores.
Bracing is very important, and not only for SQ. The very first box I made for my Stroker blew apart the first time I 'tested' it out with tones. The box I made was huge, had lots of flat panels with nowhere near enough bracing, and it actually flexed enough to tear my slot port right out. It made one hell of a noise and took me another 2 hours to fix and brace properly. If you build it right the first time, you won't have any problems with flexing.
Hope that helps.
The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.
