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A4 Boot Custom Sub Enclosure

Discussion in 'In-Car Entertainment' started by Caesium, Mar 8, 2007.

  1. Caesium
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    Caesium My BM is fixed!

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    [Mar 8, 2007]
    I started building a custom sub enclosure today in the boot of my A4
    [​IMG]
    Site of Enclosure with trim removed
    [​IMG]
    Front cover before fitting
    [​IMG]
    Front cover fitted
    [​IMG]
    Sub and trim fitted

    Only 1 problem, is that I didn't build an enclosed structure, there was very little bass, I now need to build a rear section for the box to enclose the sub, which should be interesting due to the odd shape of the space.
    #1
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  3. rasA4
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    rasA4 Four Rings Mafia Specialist

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    [Mar 8, 2007]
    very neat how was it easy to remove the trim in the car?
    is that the sub amp above the rear arch?

    good luck with the enclosed structure.

    :rockwoot:
    #2
  4. Caesium
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    Caesium My BM is fixed!

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    [Mar 8, 2007]
    Its dead easy to remove the trim, the amp on the wheelarch is the BOSE one for all the speakers.
    #3
  5. 2003 a4 sport tdi 130
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    2003 a4 sport tdi 130 Member

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    [Mar 8, 2007]
    wow... great work... my project b6 sline is in the process of an ice install.... want to do it myself. i have just done head unit with a stunning silver sony but the rear speakers dont work... any ideas???? also is there any adaptor for cd auto changer that is in my glove box or the computer display???

    have you stuck with audi head unit????
    #4
  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Mar 8, 2007]
    you need an adapter to hook the rear amp up to the Sony HU
    Sell the changer as it won't work with an aftermarket HU
    No you won't get DIS, only Blaupunkt and a few others offer DIS compatibility and the lead is about £60, so totally not worth it.
    #5
  7. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Mar 8, 2007]
    Chris, you'd be better off using the other side as there's far more room and you can fit a square enclosure behind the trim, though you do need to cut the back off the cubbyhole. You can then fit the amp on the drivers side. This is my attempt which works really well in my B6 Avant, but I really must get round to finishing it off and make it look a bit tidy-er.
    [​IMG]
    [​IMG]
    [​IMG]
    #6
  8. rasA4
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    rasA4 Four Rings Mafia Specialist

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    [Mar 8, 2007]
    Jeez wow Andy what amp is that model make
    does this feed all the speakers inc the sub?
    #7
  9. Caesium
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    Caesium My BM is fixed!

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    [Mar 8, 2007]
    That amp looks like its powering 1 set of speakers and one circuit bridged for the sub
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  10. Caesium
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    Caesium My BM is fixed!

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    [Mar 8, 2007]
    Only problem there is I have already cut the rear off of the cubby hole!
    Any idea how much a new piece of trim would be?
    I assume the N/S is bigger because of the lack of fuel filler.
    #9
  11. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Mar 8, 2007]
    Blimey you did a really neat job, I assumed you'd just left the door off, as you get a door on both sides in the Avant.
    It's much bigger, at least on the Avant, about twice the volume with no tricky curves to negotiate.
    The amp is an old school Alpine V12 F400 (£80 off ebay), powering the sub and the front Alpine components.
    #10
  12. Caesium
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    Caesium My BM is fixed!

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    [Mar 9, 2007]
    No door on the saloon i'm afraid just a cubby. Damn that saloon!
    #11
  13. dualmono21
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    dualmono21 Well-Known Member

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    [Mar 10, 2007]
    how are you going to build the back piece ???
    #12
  14. Caesium
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    Caesium My BM is fixed!

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    [Mar 10, 2007]
    with difficulty
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  15. dualmono21
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    dualmono21 Well-Known Member

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    [Mar 10, 2007]
    with ease if you know how :whistle2:

    fibreglass resin
    fibreglass matt
    fibrglass hardener
    pieces of corematt
    plenty of rolls of masking tape
    roll of tinfoil
    a dozen 2" general paint brushes
    a small plastic container
    and possibly a heat gun
    #14
  16. Caesium
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    Caesium My BM is fixed!

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    [Mar 11, 2007]
    there is a fibreglass moulders just next to my dad's house, I could get them to do it but i'd need a template first, thats a bit tricky.
    #15
  17. dualmono21
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    dualmono21 Well-Known Member

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    [Mar 11, 2007]
    make the template yourself

    remove the interior trim off the side of the car with which you wish to replicate

    now fabricate the outside edges of your box so as it leaves you with a flat edge to mount your baffle and subwoofer to (you will mount fibrglass this into the backpiece to make one piece with sides and back

    cover the area you wish to fibreglass with 2 layers of masking tape overlapping them so as no part of the fibreglass will stick to the car
    (when you create the shape try to make sure it will pull out of the cabin easilly including the fabricated sides take care with square corners and angles as they are harder to shape and harder to fit back correctly )
    once you have taped off the area you wish to use as a back piece then
    use other materials such as bin bags to protect other areas of the car from spillage

    cut the fibreglass matting into various lengths and widths and work from the outside inwards on your structure
    put the matting in place and mix the resin at a 2% ratio of resin to hardener and simply paint the matting until it is fully covered and goes allmost see through ( if you use anything other than marine resin you will have to lightly sand the surface of each coat to get the next to bond properly)

    you will need about three coats and then you should be able to remove the structure without it being damaged now add a nice piece of corematt
    to the inside of the structure and again simply paint the resin in until it is soaked through (the corematt will take a lot more resin than normal matting but is significantly stronger than matting on its own )
    now add one last layer of matting and there you have it a finshed backpiece

    your backpiece should fit in and out of the cabin with ease and the front baffle should be able to stick on easilly also

    now measure the internal volume of your sub enclosure using something like polystyrene beads (like in a beanbag) and a measuring jug
    for a subwoofer needing 1 cu ft of enclosure space there should be approximately 28 litres

    make sure your enclosure size matches your intended woofer if it is too large then fill the internals with something which will not reduce under pressure
    if your enclosure is slightly too small use a material like dakron (polyester fibre filler) which has the effect of tricking the woofer into thinking its in a larger enclosure by slowing down the airspeed inside the enclosure
    #16
  18. Caesium
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    Caesium My BM is fixed!

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    [Mar 11, 2007]
    where should I get this material from, any good online suppliers?
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  19. dualmono21
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    dualmono21 Well-Known Member

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    [Mar 12, 2007]
    if you have a fibreglass builders or boatbuiders near you
    id just pop in and ask to buy about 10 litres of resin with enough hardener to mix at a 2% ratio (its usually 1% ) but goes off quicker with 2%
    they should also be able to supply both the matting and the corematt
    should cost you about 30-40 quid in supplies then its just your own time to make it
    #18
  20. Caesium
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    Caesium My BM is fixed!

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    [Mar 12, 2007]
    Thanks very much, i'm going to take the plywood front and get them to mount a rear panel made from fibreglass to it (to the GRP specialists next door to my dad's)
    #19
  21. billybravo
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    billybravo MODERATOR

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    [Mar 12, 2007]
    see my post in the a4 forum i will stick it in here as well for you
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