sub question

grothie1978 · Post by **grothie1978** » Tue Oct 31, 2006 7:53 am

heya all

this might be silly to ask,but...
i have a 10' sub and i would like to have the magnet facing out instead of the speaker itself. is there any special way i should go about this? like wiring or sealing etc.
any help would be frickin sweet

Cookiemonster · Post by **Cookiemonster** » Tue Oct 31, 2006 8:34 am

I like the foot long sub myself. Chicken teriyaki. Very nice.

grothie1978 · Post by **grothie1978** » Tue Oct 31, 2006 9:44 am

yeah i bet u like the footlong

they are shit, cranberry turkey with ham n salad with chilli sauce :beer

Website · Post by **WidebodyWoody** » Tue Oct 31, 2006 9:47 am

I have mine inverted. Basically there is no real difference in it, but I have noticed that you get more of a kick from them being the right way around. Basically you can go with either a sealed box or a ported box. Bot don't go too big or too small because you loose bass either way. Google to correct box sizing for the type of sub that you have. And if you don't invert it and you want to get technical, subtract the mass of the sub from the space you are giving it.

grothie1978 · Post by **grothie1978** » Tue Oct 31, 2006 11:33 am

thanks buddy, got all the info needed
google rocks (sometimes)

rallidave · Post by **rallidave** » Tue Oct 31, 2006 1:59 pm

hey grothie, with the magnet facing out you will lose a lot of sound, it will be getting muffled by the back seat, if you turn it around the sound will fill the boot and sound heaps better :)

grothie1978 · Post by **grothie1978** » Tue Oct 31, 2006 2:36 pm

rallidave
so better to just do a normal sub setup? for sound performance that is?
i thought it might be like that. just that i dont wanna use up too much boot space due to kid on the way and need it for nappies, prams, shopping and all that SHIT. rofl

SIR GSR · Post by **SIR GSR** » Tue Oct 31, 2006 7:25 pm

Grothie...You are only planning on running a 10" sub. If you can't build a box that goes allows for full use of the boot space, you shouldn't have it in there. It is possible to fit it in with a stroller...

Geez it's only a 10".

I managed to fit a stroller in the boot of my civic with 2 15" subs in there...and it wasn't a small stroller...It's all about using the available space wisely.

grothie1978 · Post by **grothie1978** » Tue Oct 31, 2006 7:58 pm

tru tru
so best bet would be to use one of the sides of the boot area behind the wheel arch?
opposite side to where the jack etc is stored

SIR GSR · Post by **SIR GSR** » Tue Oct 31, 2006 9:15 pm

Either there or tucked up tightly behind the rear seat...there is plenty of space..and remember.....A sub box doesn't have to be a square usual box shape ;)

kit · Post by **kit** » Tue Oct 31, 2006 9:46 pm

WidebodyWoody wrote:I have mine inverted. Basically there is no real difference in it, but I have noticed that you get more of a kick from them being the right way around. Basically you can go with either a sealed box or a ported box. Bot don't go too big or too small because you loose bass either way. Google to correct box sizing for the type of sub that you have. And if you don't invert it and you want to get technical, subtract the mass of the sub from the space you are giving it.

This is a little bit incorrect in a few areas you can have a smaller box and fill it with durum wool tricking the sub into thinking the box is double the size. Also it depends on you music you listen to and the type of sub you buy the tighter the base the better it sounds no matter what music you listen to.

Post by **TOMSUN** » Thu Nov 02, 2006 8:08 am

kit,

I bought a sony 12" sub and I'm looking to put it in the boot facing foward neatly behind the seat. So if I want I can just lay the back seats down for better sound. (Got to leave a bit of room for a NOS kit :D )

My question is how to calculate the volume I need for the box? and how much wool do I have to put in it for a box that might be 25% smaller than the recomended volume?

Cheers,
Pete

kit · Post by **kit** » Thu Nov 02, 2006 10:04 am

How big is the box and which sony sub is it?

jakobsladderz · Post by **jakobsladderz** » Thu Nov 02, 2006 10:39 am

To estimate a woofers response in different sized boxes you'll need to find the T-S parameters for the woofer (compliance volume Vas,free air resonant frequency Fs, total Q, Qts). if you want to compare sound levels you'll also need electrical Q Qes, maximum cone displacement Xmax and the thermal power rating of the speaker in watts RMS.
On the diy subwoofer site http://www.diysubwoofers.org/sld/ there's a spreadsheet that lets you enter the parameters and get the sound level, cone excursion and frequency responce values.
Basically to give the best power handling in a sealed box you need to choose a box that is just big enough to allow the maximal cone movement from the resonant frequency down.. to
Like Kit said, you can make the box appear bigger to the speaker (so you can use a smaller box) by packing it with either polyester filling (up to 15% bigger) or fibreglass batts (up to 30% bigger). Normally when the speaker cone moves in an unstuffed box, the air changes both pressure and temperature as it compresses and expands (adiabatic compression). The stuffing exchanges heat with the air, minimising the temperature change (isothermal compression), so for the same reduction in volume (as the cone moves in), there is somewhat less pressure increase and the box looks bigger to the speaker. The reason fibreglass works better is that it is a denser substance so absorbs more heat.
Wear gloves if playing with fibreglass, otherwise you end up with itchy arms..

DD Phil · Post by **DD Phil** » Thu Nov 02, 2006 12:23 pm

TOMSUN wrote:kit,

I bought a sony 12" sub and I'm looking to put it in the boot facing foward neatly behind the seat. So if I want I can just lay the back seats down for better sound. (Got to leave a bit of room for a NOS kit :D )

My question is how to calculate the volume I need for the box? and how much wool do I have to put in it for a box that might be 25% smaller than the recomended volume?

Cheers,
Pete

Facing up or back will give more output, especially in the low end.

Dacron doesn't do squat, some people claim you can reduce the box volume by 20%, but the reality is that reducing a box from say 45lt to 36lt makes very little difference, the total Q going from 0.707 to maybe 0.82 for most systems.

Most car subwoofers work happily in boxes with a total Q of around 1.0 anyhow, the "ultimate" Butterworth alignment of 0.707 is a home audio thing......

To calculate enclosure volume of a rectangular prism its as easy as H x W x D (internal). If these are in cm, divide total by 1000 to get litres, or divide by 16.387 to get cubic inches and then divide by 1728 to get cubic feet.

For a prism with a sloping face, simply add the top depth to the bottom depth and divide by two and use as above.

Remember to add woofer and port displacement to the total enclosure volume.

Or email me, I'm happy to help. phil@ddaudio.com.au

Phil

Austarion

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