Tuesday, February 14, 2006 - 09:41 pm, by: Andrew Croucher(Soaring_dragon)
Hello all, I am a newbie here, have had my soarer for a year now, have installed a dvd player in the glove box, running it through my screen. I have had my Sub and amp for a year now and have finally built up the motivation to install them.
I bought a 10" Boston acoustics Pro series sub and a Boston acoustics GT-24 Amp. 900watt mono. The reason why i bought the 10" and not a 12" or 15" is because i want to replace the factory sub with the 10" Boston w/ a Custom box.
I want to know whether anybody has built a box for the parcel tray and made clearance for the gas tank??? No one has ever written about it in the forums i've been to... I have been dying to know. I also didn't want to get a free air sub, I am a huge Boston Acoustics fan. So i need to make this project work.
If i raise the sub by 3 inches with spacers i will have clearance of about half an inch after putting some kind of box under the parcel tray. I will need to seal the box completely along with the spacers. I was told to build a box out of fibreglass too... Does any one know how much it would cost? I'm going for pure SQ. So i want the sub in the cabin.
Any help will be greatly appreciated... pictures will be posted as a install my amp and sub.
Tuesday, February 14, 2006 - 11:00 pm, by: Mark Paddick(Sparks)
Dunno 'bout music but electronics and in particular speaker design I do know heaps about The box size is going to be around 21 litres for a sealed or 35 litres for a ported enclosure. Probably the easiest way would be to use thickish MDF (19mm minimum, preferably more) with tar coating on the inside and actually include the fuel tank inside the box. This would mean that the rear panel would have to be made removable. The rear channel speakers must not be included in the box. Any sort of fibreglassed enclosure will not have the rigidity required and will not be easily made removable which is an absolute 'must' as sooner or later you will need access to the fuel tank. In this sort of setup you may want to paint the outside of the tank with a very thick coat of the tar as well or you will have problems with the tank flexing when less than full (when full it will be fine; near-perfect in fact). The proximity of the tank to the rear of the speaker also dictates that the tar coating is essential and must be thick (1/2 inch at least). In this respect the curved upper surface of the tank will be a good thing helping to reduce internal reflections, something that will be very hard to do with a box that does not include the tank; the box in this case will be even closer to the rear of the speaker making things worse all round. 1/2 inch clearance for a flat surface under the speaker is nowhere near enough unless that 1/2 inch was completely tar filled which would make getting the required 21 litre box volume difficult indeed. Fibreglass boxes are absolutely useless for deep bass unless double walled with a high density substance sandwiched in the middle (tar sheet or similar). They would also have to have the tar sheet on the inside of the box too whereas a wood box is not anywhere near so fussy to build. The density characteristics of fibreglass do not suit speaker box design at all unless for middle to high frequencies only. The density of MDF is much better suited to speaker enclosures although a coat of underbody tar sealer on the inside would be beneficial (much cheaper than tar sheeting). To get the design right AND sill have fuel tank access is not going to be easy but will be worth it in the end. A ported enclosure will be a lot more tolerant of any small leaks whereas a sealed enclosure must be exactly that - sealed. The exact volume of the box will be hard to work out too. Err on the small side and use 'Innerbond or similar wool - like substance to increase the effective volume (and reduce internal reflections) Skimping on the enclosure will mean that a good sub will be wasted. Cost will depend greatly upon how thoroughly the job is done and whether you do it yourself or pay someone else. If I were to do it you would be paying heaps as it is not my favourite sort of work. Materials would be relatively cheap ($100 to $200) but labour would be hellish as it could run into days rather than hours to do it properly. As a side note the Boston acoustic stuff looks to be very good however the power figures given on their website have no reference at all and are therefore totally meaningless and I do mean TOTALLY MEANINGLESS. I suspect this is an advetising person (I use the term person loosely ) shortcoming as the reputation of BA is far better than that!
Wednesday, February 15, 2006 - 07:30 pm, by: Andrew Croucher(Soaring_dragon)
WOW! Thank you for the prompt reply. What would be the name of the tar and where can i get that from? Bunnings warehouse? I would like to get the best tar to seal and rebound sound.
Looks like that is the best solution for me... If i attach the sub box to the gas tank, what would i do with some of the wiring? can i build a small cover for the top of the tank and then paint tar over the cover and everything else?
And if the box it attached to the gas tank, would it be stable when i turn corners? Just wondering if the parcel tray will twist with the chassis and gas tank.
Also, how would i mount the wood to the parcel tray and the gas tank? super glue the bottom pieces to the tank and screw the top parts to the parcel... is the metal aroudn the parcel tray removable?
Wednesday, February 15, 2006 - 10:35 pm, by: Mark Paddick(Sparks)
Car underbody sound deadener, Supercheap should have it. Or talk to you local council road workers for the real stuff. You'll have to do some measurements and calculations but I think the box will be a bit bigger, possibly enclosing the entire tank. Jaycar sell tar/aluminium foil sandwich which would be good for covering the fuel sender as it can be laid on top and would be easily removable.
Thursday, February 16, 2006 - 10:20 am, by: Perry Morgan(Uzz32)
Maybe mount the box against the underside of the parcel tray using the available bolt holes instead of mounting down on the tank. It wants to be sealed against the parcel tray anyway.
Thursday, February 16, 2006 - 11:15 pm, by: Andrew Croucher(Soaring_dragon)
Thanks guys, Murray, Thank you for the aperiodic membrane info. My sub is .8 "Q". Too heavy for this setup.
My idea is the raise the sub with spacers. 2.5" high. and to somehow build a box ontop of the gas tank. Have to find a way to get round the cables. Does anyone know if the cable close to the tank will vibrate and make alot of noise? any way of getting around that?
i will definately need big spacers!!! And does anyone know what i would use to cut the metal around the sub hole with? I heard tin snippers. but will they be strong enough? will i be strong enough???
Friday, February 17, 2006 - 12:00 am, by: Mark Paddick(Sparks)
Picture ten two litre milk containers. In fact collect ten of 'em and try to fit 'em in, that is the internal box volume required (plus a half one) for a sealed box. I don't think they'll fit above the tank. The box should not be too narrow in either depth, height or width and preferably not a regular shape either. No parallel sides would be best. This is to reduce internal reflections. When finished the box should sound completely dead if you rap you knuckles on it, no echoes, no hollow sound. It is the speaker that you want to produce sound not the box. This is the reason for the tar. A plain box will always sound 'boxy' which is why most cheap stereos sound crappy. Tar is messy and hard to work with so most don't use it. This isparticulrly impotant for a sealed enclosure, ideally it should absorb ALL sound. Good sound does not come easy. Good bass from a sealed box is ALL about the box. Good tin snips will cut the shelf easily. Wrap the cables in foam, underfelt (like the grey stuff in the car) or Innerbond and tape it on. Won't rattle then if you make sure the foam and not the tape is the contact point with other surfaces.
Now that I've found the correct spec sheet it appears that a box volume of 14 litres will do (7 milk containers). Qts is 0.44 to 0.53 NOT 0.8 which is Qms
I'm beginning to wonder about Boston Acoustics. This is the third different set oif specs I've found for that speaker.
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) shortcoming as the reputation of BA is far better than that!
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