Just Finished a Custom Sub Box for my Lanos Hatch ... Pics

naznomad · Post by **naznomad** » Tue Jul 31, 2007 4:56 pm

Just thought I would share this with you. I had a big sub box with 2 tens in it,but it took up most of my hatch space. After reading posts and looking at how to's online,I decided to make a fibreglass enclosure to fit in the side of the hatch,and use the 2 subs that were in the box.. Comments welcome,but bear in mind t's my first attemt,so it's not brilliant,but I kind of wanted to use it as practice for when I get another car so hopefully I can make a better one next time. Having said that, I got it all hooked up yesterday and it actually sounds good,which I suppose is the main aim.

OK here's some piccys

First one.This is where the box is going to sit.This shows the plastic trim piece taken out.

This shows the whole area taped up with masking tape.I also used some sheets of aluminium foil to make it easier to release the back of the box after the first soaking with resin.

I decided to put a layer of cloth down first ,soak it with resin,let it dry,remove it,and then do the glassing outside the car. Trying to stick bits of fibreglass in there initially is too awkward. For this i just used an old bedsheet.

This is it dry after a good soaking with resin

Then I pulled it out,which was made easier by the fact I used aluminium foil as well as masking tape.

Here it is after 3 layers of glass and resin,sitting next to the plastic trim piece

Next I used a piece of cardboard to make the template for the front of the box,where the speakers would be fitted into. No pic of that step,I forgot ! But here are pics after I had transferred the template pattern to 3/4" MDF board,and cut the holes for the speakers.Also shown is a hole I cut so I could mount the amp to it. I covered the hole from behine with a piece of MDF so that the amp would be slightly recessed in the board.

Next I attached the front piece to the back with 1" dowel and hot glue.

Then I fibreglassed a few layers over the exposed bits to enclose it all

After it dried for a day,I wrapped it in carpet (cheap stuff!) and test fitted it

This is with the subs attached. The box is sealed pretty good i think,press on one cone and the other one bulges out. I havent got round to putting the amp in yet,its still in the front of the car,and I have to re-route all the wires for the door speakers,so who knows when I will get around to that !
As for the wires to the sub,I drilled 2 holes in the back to let the wires through,and hot glued around them to seal the hole. I also made quick-release connections so the box can be just pulled out and the wires detached by the male/female spade connectors.

Now I have lots more room in my hatch area !!

whiteraven · Post by **whiteraven** » Tue Jul 31, 2007 8:14 pm

I want one for my Aveo!!

WoOtYwOo · Post by **WoOtYwOo** » Wed Aug 01, 2007 12:42 am

very cool

naznomad · Post by **naznomad** » Wed Aug 01, 2007 2:37 am

WoOtYwOo wrote:very cool

Thanks !

WooJD · Post by **WooJD** » Wed Aug 01, 2007 2:57 pm

lol this isnt a bad first go, it's a fucking good one!

mezomaster · Post by **mezomaster** » Wed Aug 01, 2007 4:37 pm

its a great job really i love it, just got one question, will this become good in bass and woofers?? i mean it will be strong enough to hold the vibration which happens from the woofer and make the bass good?

WooJD · Post by **WooJD** » Wed Aug 01, 2007 5:43 pm

just thought the stock speakers right above it kinda will work together...

JOKE INTENDED!

naznomad · Post by **naznomad** » Wed Aug 01, 2007 6:29 pm

WooJD wrote:just thought the stock speakers right above it kinda will work together...

JOKE INTENDED!

The only thing those rear spks are good for is target practice !

And to mezomaster,it should work ok as long as the box is made thick enough with the fibreglass. You need at least 3 layers because less than that it'll be too thin.

mezomaster · Post by **mezomaster** » Wed Aug 01, 2007 6:34 pm

cool, that would be a solution for most of my friends then, not for me yet cuz i dont have an aftermarket sound system yet LOL

Post by **PrecisionBoost** » Thu Aug 02, 2007 5:09 am

I noticed that you didn't do anything with the inside of the enclosure after fibreglassing.... this may end up causing unwanted resonance.

I hate to mention it.... but I'm an electronics eng. tech and I use to build competition (IASCA quality) stereos (for myself and others) so I've made about fourty boxes.... many of them fibreglass.

The only reason I didn't want to mention this is because I allready get a ton of PM's asking me about car stuff and my time is really limited these days.

So...... I don't usually respond to these questions.... in fact.... I quite often skim the eletronics/interior/audio section because I know I won't have time to answer everything.

Ok... back to the subject.

Ideally to remove resonance you should have fibreglassed an MDF cross brace inside the back of the enclosure.

I would normally take a piece of cardboard and simply cut it out until it fits perfectly in the back.... then I transcribe the cardboard to a piece of MDF and cut it out with a jigsaw.

You don't need much for the cross brace.... it could be roughly 1" to 1.5" thick.

So.... next you fit the cross brace and fiberglass it into the rear..... and the MDF will absorb most of the movement.

If it were me... I would also add some dynamat to the rear and sides to absorb any extra vibrations.

I've even used a thin coating of Mineral wool (basicly thick insulation made from steel slag) around the inside of the chamber to get rid of resonance.

Additionally the mineral wool will absorb some of the energy from the speaker and make the box seem bigger than it is volume wise.

Some people like to use cotton fiber fill (same stuff used in pillows).... which works good for increasing the effective volume of the box but I don't think it helps with resonance... it's too soft to absorb the primary shock wave from the subwoofer.... but that's just my opinion.

mineral wool is cheaper than dynamat material...... I have also used spray on bed liner to reduce resonance to practically zero...... it's very effective at absorbing energy.

Anyways.......... my daughter is out of bed and I have to go tuck her back in..... just thought I'd mention the resonance issues.

Chris

naznomad · Post by **naznomad** » Thu Aug 02, 2007 6:59 am

Good points PB. About a cross brace.I didnt even think about it! But would that not cut down the interior volume of the box because it would have seperated some of it off,like the back section if a brace piece was glassed in right? . Could it be done with several thick pieces of dowel to strengthen it instead of a flat piece of MDF ? I could probably still do that now,just work through the speaker holes in the front of the box !
But oh well,its just an experiment more than anything.I was bored one day and just started doing it. No way was it ever going to be up to the level of some of things i've seen. I'll know better for next time !!
I mean,it sounds ok,but I guess I wont know any different til I do something with it.
I have some of the fibrefill stuff,I might pull one of the subs out and put some of that in. I also have some foam rubber,like an inch thick,would that be better than the fibre fill stuff in there? I remember I had an isobaric sub box a few years ago,and that had some of that foam rubber inside.That box was ported though,don't know if that made a diff as far as the foam rubber goes.
Anyway hopfully next time I'll do a better job,I'll probably spend more time on it,especially if I get a decent car worthy of it

Post by **PrecisionBoost** » Fri Aug 03, 2007 12:17 am

Honestly.... you may not notice anything with the system you have.... I usually push at least 600 Wrms into my subs.... so they produce a massive amount of force on the box.

The dowel might work... never tried it.... you'd probably be better off just throwing some foam rubber and or fibrefill in there to help dampen any internal movement of the box.

I personally like the spray on box liner because you can apply it with a brush if you need to..... but it's not exactly the cheapest stuff out there.

As far as the brace is concerned..... if it's 3/4" and only 1" in diameter and say 30" in length that's only 22.5 cubic inches of space used up... which is only 0.013 cubic feet of volume

0.013 cubic feet is practically zero... the fibre fill may add up to roughly 0.2 cubic feet (rough guess)... so 0.2 cubic minus 0.013 cubic gives you an additional 0.187 cubic feet of volume with the fibrefill.

Every filler material is differnent.... like I said... it's just a guess based upon a rough estimate of your current volume.

I wasn't trying to say that you should take your sub box apart.... you did a very nice job.... I especially like the use of a bed sheet.

I just wanted to give you some pointers for the next time...... so good job..... keep it up.