Mounting Amps under false floor
After seeing some neat boot setups i've gained a bit of interest in the whole false floor idea. I figure it'd be a good way to hide away all those things you don't really want to have showing. My question here though relates mostly to amplifier heat. Now i'm aware it's a bad idea to mount your amplifier upside down as it almost defeats the purpose of the heatsink, so here's what i've planned to do:
Cut to size a thin sheet of MDF and lay it on the floor of my boot.
To this sheet, mount my amplifiers (the correct way up, NOT upside down).
Then I plan to have the actual false floor made out of say 16mm MDF and propped up about 8cm or so from the actual floor leaving enough room for the amplifiers underneath with a few centimetres clearance. So basically the order of things goes thin sheet of MDF on the bottom, amps mounted to this, then False floor above this covering up amplifiers.
My concern is that being underneath there and in a confined space the amplifier won't have enough room to air... would this be true or would that fact that there would be quite a large surface area under the floor mean the heat could still dissipate properly?
P.S. - anyone got any pictures of making a false floor hanging around and how did you all do it? I was simply planning on screwing the top piece of MDF onto a few chunks of wood underneath and around the edges to prop the sheet up a good 8cm or so from the actual boot floor.
Cheers.
Physics Geek
It's something I've been looking at for a while, trying to hide the amps under the false floor. If you're worried about them being a little too hot, then a couple of small 12v fans (like the ones out of computer power supplies which are about 8cm) hooked up to a relay switched through the remote wire from your headunit would work quite well. That way they only come on when the amps do, and they just keep the air moving through there.
I don't know if you need the fans or not, but allowing for how much a good amp costs (compared to how much I earn!) I'm not going to take any chances with mine.
Gravity is proof that nature keeps getting us down.
VL Calais 5L
yeah you do need the fans - i run 2 of them
You start alot of new separate topics
http://www.caraudioaustralia.com/ forums have lots of info on install ideas and stuff. Maybe search there when you need info
Ah ok yeah i now remember seeing that done elsewhere the whole fan idea. So is it fine to buy the ones that actually ARE made for computers and just use them or do they have ones specific to car applications? Also about hooking it up to a relay... Could you simply tap the power wire of the fan into the remote wire for the amp and wouldn't it still turn on when the headunit was turned on and turn off when the headunit was turned off?
Question going out to Girl Torque, how did you construct yours? See the tools i have at home are shizza, i figure i'd probably trace onto cardboard where i want the false floor to sit and then cut that out, then trace that onto the MDF. I'm just not sure how flush it would end up sitting though and how tight fitting, especially at the back there where the boot angles up to that little ledge just behind the back seats where the vertical side of the MDF would probably need to be angled to sit flush. Also what about securing it? my plan was to pull the boot carpet up, have the bottom thin sheet of MDF layed down on the boot floor and screwed into the wood chunks which would be sitting on top of it, then the top sheet of MDF screwed into the wood chunks which would be below it and then simply lay the boot carpet back down over the lot. Just worried about two things, how secure the false floor will hold in without being stuck to the actual car (relying on the weight of the MDF and a tight fit) and whether it would cause any rattles with subs (although i was hoping the lying the carpet back over the top would eliminate this).
And StoneX, i start the seperate topics because then you have a better chance of getting an answer if people can know exactly what your asking about. For example if i'd wired an amp up but hadn't made a false floor and someone had a post "false floor" that was also asking about wiring an amp i probably wouldn't read it because i wouldn't be interested. Just helps keeping everything clear, not to mention making searching for information alot easier when you need it when everything's categorised under a title that suits it's content.
Physics Geek
It's best not to have things drawing power from the remote lead, for the simple fact that most of them are only rated to about 250mA. Most computer fans (and yes, computer fans will work fine for what you want to do, they're just a 12v fan) are rated at somewhere between 200mA and 400mA. I have got one here that's just more than half an amp. So a relay is a good way to do it.
If you don't mind being a bit of a scab, just wait until someone is throwing out a computer and rip the powersupply out and take the fan. If there is a school nearby, ask them if they have any dead computer power supplies kicking around. Schools are normally only too willing to give their junk away, sort of explains why I have a box of 45 computer power cables
Gravity is proof that nature keeps getting us down.
Ah yeah i was just thinking about what i said on the way home and see what you mean there. If i still have spots left over on my distribution block couldn't i relay it using that instead of running wire all the way back to the battery again? Also is it hard taking the fan out of the computer power supply? P.S. - about to hit up my old school for some old computer power supplies, wish me luck.
Physics Geek
Takes 3-6 screws to pull the case appart. Then four screws hold the fan in. There will be two wires, one red one black, snip those and you're done. Just be careful in the powersupply itself as a few of the capacitors can give you a nasty kick.
Gravity is proof that nature keeps getting us down.
a nasty kick that's going to give me a little zap or a nasty kick that's going to hospitalize me?
Physics Geek
It'll give you a bit of a zap, that's about it. However if you've got a pacemaker I wouldn't recommend it.
Ever licked a telephone line?
The good thing about getting a shock from a capacitor (one of these ones anyway) is that once it's discharged...that's it. Whereas if you get a shock from a battery or power point (or ignition coil
27,000Volts and FEELING FINE
Gravity is proof that nature keeps getting us down.
How do you go about accessing the spare tyre if you put a flase floor over the top of it?
You can hinge it or just not have a spare... Some people just have the "Tyre in a can" thing which reinflates a flat tyre temporarily.
Tyre in a can??? tell me more... sounds like a good idea
Ok, scabbed some power supplies
hot air doesn't cool. for best results you will need to push it out into the boot space.
are you talking about removing the spair tyre or just not being able to get to it? you can get booked for not having a spair.
Well in my VS the spare tyre is on the side. I'm planning on leaving it there where it is. Don't worry the false floor's going to be in a manner that still allows it to be removed if the spare tyre is required. Hey Dephile with removing the hot air into the boot space, i plan now to cut holes in the false floor top sheet of MDF and then prehaps put some holes in the carpet above the fans so the air can escape. I've butchered the power supplies and tested the fans on a little 9 volt battery to make sure they work. I notice if you put your hand on the one side of the fan the breeze is alot heavier than on the other, and that they also have little arrows showing you which way the air is going... I'm assuming that i'd face these with the arrow up going into the boot space and that it pulls the air through the other side of the fan does it? It's just alot harder to feel something pulling air through with your hand than the resulting air on your hand, just wanting to check that's actually how it's working so i don't mount the fans the wrong way
The arrows indicate the direction of the air flow. The reason the fan feels stronger on one side is because it pulls air in through the back and blows it through the front.
You are correct - You will need to blow the hot air OUT of the false floor.
When trying to remove heat you want to work with the convection current of air (heat rises so don’t force it to go down with fans).
It is probably debatable if blowing air in or out of the false floor is better or worse. Blowing air out of the false floor into the boot space would probably work better with the convection air currents I mentioned above. But I think you will find a heat sink cools better when it has a reasonable amount of air moving over it (i.e. blowing air into the false floor).
which ever way you choose, i don't think you will have overheating problems
In that case you could use two fans to circulate the air.
Have one facing up to blow air OUT of the false floor and the second one
blowing air INTO the false floor.
yeah well i've attacked 4 power supplies so far, so prehaps i'll go for 2 facing down and 2 facing up. Cheers fellas.
For puncture repair theres stuff called "Slime" it prevents and repairs flats instantly.
Physics Geek
^^^And the tyre industry hate it because it unbalances your tyres like you wouldn't believe. It works in an emergency, but I think I'd rather just have a spare.
Gravity is proof that nature keeps getting us down.
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