building a sub box - few questions

[michael_antoi]

ok well I bought a 12" clarion proaudio series sub and i'm about to build a square enclosure for it.


dimensions for each square piece will be 320x320x18...

it will be a sealed box and the fact sheet i got from the sub indicates the enclosure airspace = 21.85 litres

also F3 = 65 Hz..


are my dimensions ok for this type of sub?


Also, the fact sheet says the mounting hole will be 10.98" so that means I would have to cut the hole to that diameter?


I'm just starting out in car audio so any help would be much appreciated.


Thanks

[HRV-80Y]

yesh wateva the recommended volume of the sub enclosure says by manufacturer you should follow evn a lil bigger is better...

wit the diameter of the whole if thats the measure ment they have given u den so it should b cut to that size...

also depends on which kind of sub u have...i.e. open air sub or sub made especially for enclosures...u might need a ported whole...

[SIKCVC]

that box is a little large for 21 ltrs... its been a long time since i've done subboxes, but those dimentions seem to add up to a 32 ltr box.

PS dont be boring and make a square... no one wants to look at a square. doesn't take much to put a sloped face or elongated box, or even fit it into a corner somewhere so its out of the way.

[J-MuN]

make sure u have a curve in the box or else all your specs u following will be useless..

[urtwhistle]

yeah u dont want no paralell faces in the box or the sound reflects inside the box and wrecks the sound performance i'm preety sure.

not 100% tho

[micka]

yeah u dont want no paralell faces in the box or the sound reflects inside the box and wrecks the sound performance i'm preety sure.

not 100% tho

a sub box is generally too small for a sound wave to occur, (volocity= frequency x wavelength -> 340=80wavelength -> wavelength for 80Hz soundwave = 4.25 meters) inside the enclosure is air pressure change. Lowpass filters are usually set to around 80Hz for subs, and thus lower frequencies will have longer wavelengths. Its much more important to get the internal volume good and the enclosure properly braced and sealed than to worry about parrallel sides.

[Fhrx]

Micka is spot on there. Unless your enclosure in literatlly meters long you will not have standing wave issues within a sealed enclosure.

michael_antoi, post up the T/S specs and I'll design the best enclosure for you if you wish?

[Boost]

yup like micka says, also make sure u use the correct mdf thickness. too think will be weak and flimsy..and i think that will affect the sound.

[urtwhistle]

oh ok, is that just with sealed sub box's FHRX?
cos i remember when i got my custom ported box's they specificaly said it had to have no parrallel walls ,

[Fhrx]

Ported enclosures are a whole different kettle of fish (where the hell did that saying come from anyway?). The reason why is because you DO have to be concerned about what the rear wave sounds like in ported enclosure.