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Advice on building some SPL sub boxes

acarmody

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OK I've been crunching numbers and no matter how I work it, its going to be bloody close. I drew up a template and spent ages working out how to make these fit and this is the best I can come up with. Now if as above I screw the far ends of the sub into the side walls I will have 350mm square to play with in the middle of the box. Now it doesn't matter if the side of the flares overlaps the 350mm because the inside of the box has plenty of sideways space (because sub is narrower at rear), and in the front it can overlap the frame and the rubber suspension without problems right? But it can't overlap the roof and floor of the box on the inside but it can on the outside. So looking at the diagram below (the bottom and side labels are purely for reference so you can visualize what the hell I'm saying) if I sand of the bottom 1cm of the flare on each sub and put the flat against the roof/floor of the box, AND I shave a few millimetres where the two ports meet on both the inside and the outside, it should fit.

Does this make sense to you, and can you see any glaring holes? Apart from the fact the ports holes in baffle will need to be millimetre perfect (I'm getting cabinet maker to cut holes hopefully).

snc002991.jpg
 

holdenboy

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No im serious, most sealed setups with around 1000wrms in commodores do 130-133 maybe, i'd expect 140-142s out of this setup.

Yeah i always knew fitting 2 flared 6" ports into that box wasnt going to be easy....so yeah, just cut the overlapping parts of the flares off, its not a huge sacrifice and if it allows that much port area to be used then the gains far outweigh the cost. Use those MDF "ribs" behind the baffle to strengthen it and provide more "bite" for the sub mounting screws.

I think ive made sense of your plans......just keep posting up pics as you (your Dad) go ;)
 

acarmody

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You bet I will! I'm absolutely stoked about this comp.

One more thing, will painting the ports do anything bad? I was thinking black for the ports and for the inside off the back wall, so if you look into the port its just black.
 

holdenboy

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Painting them is fine.....just get some fibreglass resin for the inside of the box first.
 

acarmody

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Painting them is fine.....just get some fibreglass resin for the inside of the box first.

Well that also answered my next question. Yeah my dad and I were discussing putting fibreglass resin on the inside edges.
 

holdenboy

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Yep, paint it on with a brush (mix with catalyst first ofcourse), do 2-3 coats and use it to seal the box joins internally. I used to go a step further and make 45 degree corners using resin, it didnt help with SPL though.
 

acarmody

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Well I picked up my MDF today, and I must say that 25mm MDF officially weighs about one million tonnes. I had to unload the 2 sheets myself and drag their asses to the shed. I've also now come to realise that one sheet would have done it, *sigh*, oh well I'll just have to think of another project now. On another awesome note, when I picked the wood up, I found that to preserve the MDF sheets they had used a 3mm MDF sheet on the bottom and a 16mm MDF sheet on the top, FREE STUFF, my dad needed some 3mm for picture backing, and I'm sure I can find a use for the 16mm stuff.

Anyway after dragging their asses to the shed I declared war on the MDF, I won. I didn't have to long though because it was 7pm when i was doing this and the next door neighbor is a truckie who I know gets up early, and my dads circular saw isn't the quietest thing.
snc00301.jpg


And I thought I might as well take a photo of my dads getaway. There is other equipment you can't see like the lathe and the leveler machine and an assortment of hand tools.
snc00302b.jpg


Tomorrow I'm hoping to finish the ports, and maybe to visit a fibreglass shop and see about some matting, who knows :whistling.

Also question, will those plastic square box terminals that you can pick up from any WOW, JB, etc, be strong enough for this box, or will I need something stronger? These are the ones I used on my sealed boxes, http://www.aerpro.com.au/list.php?p...t_name=Square+Speaker+Terminal+Board&cat_sno=
Also do you recommend just screw on cable or banana plugs? I was looking at these, supports 4AWG, http://www.uglycable.com.au/connect...essional-gold-plated-banana-plugs-ug940.html#
 
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holdenboy

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Shed looks good.....wish i had something like that :(

I never used box terminals, i just drilled holes big enough for 8AWG power cable to go through and sealed it up with silicone etc. (from the inside and outside). I think once i used some adhesive in a tube as i didnt have any silicone at the time......during testing i re-sealed them with silicone and gained 0.3db, haha.

If i was to use terminals at the box, i'd just strip 20mm or so of insulation and insert into the holes, making sure the cable goes through both holes and tighten up the post.....not too much though because if its too tight it can cut the copper wires.
 

acarmody

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Just checking something, if 1/3 of the flare doesn't count, and with 35mm flare, shouldn't I make the ports ~446mm long?
 

holdenboy

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Yeah that'll be fine.....hows it coming along?
 
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