My Chippy Mate Is Making My Boot Build This Weekend...

[tommk3cab]

make sure you try your best to get the correct internal air dimensions, and, if you have the space mount the subs with the magnets facing out of the build, so backwards to how most people put them in a box ( or else it would tip over!)

99% of subs come with a box for a reason..... having the magnet pointed outwards only works with certain types of subs known as 'free air' a normal sub needs an enclosed space to work properly, and that why each sub has a reccomended enclosure, be it 1.2cu feet, or 1.5cu feet, it will be slightly different for every make of sub out there.

they are enclosed though or should be, just from the other side. ive just heared it can make them louder, never had any experience in practice.

i get you... so they fire into an enclosure, rather than having the enclosure around the magnet and coils... hmmm, might have to try that with my JL when i get an afternoon free 

your not wrong though, there are subs designed for free air, or at least a system called ' free air' but to be honest its always puzzled my how that would work, maybe its similar to like 6x9's in a parcel shelf or like a wall dividing the boot off from where you sit ( like in a transit van! ) and the sub mounted in that wall, ive seen that done before.

[mase]

make sure you try your best to get the correct internal air dimensions, and, if you have the space mount the subs with the magnets facing out of the build, so backwards to how most people put them in a box ( or else it would tip over!)

99% of subs come with a box for a reason..... having the magnet pointed outwards only works with certain types of subs known as 'free air' a normal sub needs an enclosed space to work properly, and that why each sub has a reccomended enclosure, be it 1.2cu feet, or 1.5cu feet, it will be slightly different for every make of sub out there.

they are enclosed though or should be, just from the other side. ive just heared it can make them louder, never had any experience in practice.

i get you... so they fire into an enclosure, rather than having the enclosure around the magnet and coils... hmmm, might have to try that with my JL when i get an afternoon free 

your not wrong though, there are subs designed for free air, or at least a system called ' free air' but to be honest its always puzzled my how that would work, maybe its similar to like 6x9's in a parcel shelf or like a wall dividing the boot off from where you sit ( like in a transit van! ) and the sub mounted in that wall, ive seen that done before.

yea i know... i think they work on a similar princable to 6x9's, my mate has 2 tens in a MDF parcel shelf... real real punchy, but not very deep, so i dunno really... im defo going to try mounting my 12" upside down this weekend tho, prob give it a bash tomorrow after work really and report back.

but as has been said, wandering slightly off topic here, so sorry ashmond, cant help u with the design, but at the end of the day, u can have pretty much whatever u want (within reason and boot space) www.autoacoustics.com do custom enclosure and im sure they have several fotos on their site of work thats been done, might spark an idea off. 

[Ashmond]

Ok thanks dude no worries, thanks for the link

[Heyho]

800 watts out of each and actually the 15 has one of the amps powering it alone, so trust me its powered well enough

Just need to get a power cap, but to be honest thats not what I made this thread for and its going right off topic, I wanna know if there are any websites that show boot builds, so i can get some ideas.

Are those the peak or rms ratings?  Peak ratings mean diddly squat.  What size fuses do the amps run?  I can give you a pretty good indication of actual power from the fuse raings.

Also, the money you'd spend on a powercap would be far better spent on wiring,  a higer capacity battery or some sound deadening - caps don't have any real benefit, they just look a bit bling.  Sorry to wander off topic, just trying to give some advice!

[DubFan]

Slightly off topic again, this whole sub-enclosure thing.
I'm not an ICE expert, but I'm a sound engineer and have studied acoustics.

The bigger the speaker, the more air it can move, so therefore it needs a bigger enclosure.
The bigger the enclosure, the lower the resonant frequency * (ie it will give you that deep d'n'b sound).
The smaller a speaker, the quicker it can move, so your 12inch sub will give a punchier bass, but because the sub and enclosure is smaller, it won't resonate at the lower frequencies, so won't give you as deep bass as the 15inch.

As for using the two subs together, there are no technical problems, so long as a) they get the same mono signal, b) they both face the same direction.
The 15inch sub will give you that lower deep bass, and the 12inch will give you the slightly higher kick/punch bass sound. Any sounds/frequencies in between that both subs can provide will just be louder because it's coming from two subs and soundwaves (ie air pressure) always add up, making it louder, provided that (as above) a) they are from the same source/mono signal and b) the speakers are firing the same direction.

Basically: If you want to use both subs, go ahead, run them both in mono, and pointing the same direction. If you get a point where the two subs act together and you get annoying frequencies, you can tune that down with your EQ to your own taste.


As for your build. Here are three options.
1) just use standard sub enclosures and fix them down
2) build the whole thing with MDF and cover with carpet
3) build the base of it with MDF, then mould something really slick, rounded and shiny with fibreglass over the top

Make sure it's on a big bit of mdf though, so you can lift it out and get access to your spare wheel.
If you don't need a spare wheel, you could mount a sub or amp in the wheel well and make a feature of it.
Remember that all the MDF, subs and amps will add weight, hence why some like the lighter fibreglass option.
You will also need to run decent power cables from your battery cos amps for subs take a lot of power.


*If you don't know what a resonant frequency is, it's the frequency as which the object/box/enclosure naturally vibrates/resonates.
To test this out, grab 2 wine glasses, one bigger than the other, place on a table. now hit the side of the smaller one with a pen, now hit the bigger glass. The bigger glass has a lower resonant frequency, and the smaller glass will give a higher "ding" sound.

[Heyho]

I see what you're saying dubfan, and it does make sense, however:

Using 2 subs of different sizes, possibly in the wrong enclosures, and possibly disproportionately powered may cause all sorts of unpredicable results.  You've already said that the 12 will move quicker than the 15, meaning that the larger sub may lag behind (this is difficult to say for sure, the 12 *could* lag behind the 15 given the fact that they are totally different drivers), causing cancellation.  One cone could still be moving forward, while the other has already peaked and on it's way back towards it's centre posoition.

Being a sound engineer, you'll know that it would take some pretty mind boggling maths to even get close to predicting the actual results.

[Len]

So Ashmond how did the build go?

[Ashmond]

Didnt get round to doing it as had a higher priority to get done:



Got my 20vt engine hanging instead 

[Len]

Yea did have a look at your project page!

[DubFan]

Nice engine swap.

heyho, I see what you're saying, it is tricky maths to work out that sort of stuff. Mostly I work by knowing the theory, but if it sounds alright/good/better then go with it unless it will cause you problems later on.

So many variables with acoustics anyway, what materials you use, how you mount everything, use of deadening material... etc.
Not to mention things like cable length/gauge, quality of components, power capacity of the battery/alternator/psu.

Anyway, it's all up to personal taste in the end. I like as pure a sound as possible with the whole frequency range balanced, but in a car that's unlikely to sound good because of all the noise, so try out different set ups and setting to see what you like.