Cool Your Jets (er, amp) Boy
 

Anyone have an aftermarket amp in their trunk? Not all the time, but once a month or so, I'll go on a "long" trip, you know, more than 20 minutes, and my amp will sometimes overheat, and cut out. It's mounted in my trunk.

Anyone found a simple answer for this? I guess there's no sin in a fan, if it goes out, the normal thermal protection will work, but... I'd love a way to get "natural" air flow from driving, without running the risk of getting water in there.

I do always have the top down... Perhaps scoops by the fuel tank would work.

http://abefm.smugmug.com/photos/513010153_LQzDL-L.jpg

That amp looks ENORMOUS>.. are you driving more than just that sub with that {i hope so}.. If not , downsize. let a smaller amp do the work that a larger amp does without all the excess overkill.

I have NEVER with a single one of my cars had an amp cut out due to overheating.
Perhaps you are overpowering your sub and its causing the amp to cut out, that happened to me before. I unbridged the wires and turned down the amp power output and all was well again. I have a 750 watt pioneer amp powering a 500 watt kicker sub in the subaru and I've gone on multiple 4-5 hour drive's with absolutely no problems.

Mine is mounted to the floor and has a built in fan, which is usually covered up by a large bag, never had it overheat.

http://www.boostedmiata.com/projects...subbox_003.jpg

abe, what's the amp rated (RMS) and what's the sub rated (RMS/ohms)?

As everyone has said, that amp is far too large. If you want to keep your amp crazy cool, pick up a Bazooka amplifier that is CHILL compatible, and then buy a CHILL kit. It's a full coolant cooled amplifier system. Otherwise, I mounted my amplifier on the deck behind the seats. With the top down you get a great breeze over it.

On that note, I've never had an amp overheat.

I have two amps mounted to a panel in the well of the trunk and usually covered with my toneau. Never had either cut out. A simple test would be to place your mount ont he floor of the trunk and see if it still overheats. The way you have it mounted right now sure isn't helping the amp cool properly. Heat rises. The heat from the fins on your amp is going right back into the amp.

I had my oldschool Rockford amp and my current MTX go out due to heat when I had them in the spare tire well and a false floor over them and my golf bag on top. I'm moving them to the same place as AbeFM and will add a couple cpu heatsink fans with a bosch relay just to get better airflow over the heat sink.

The RF was pushing two subs running 2 ohms though. The MTX simply is getting no airflow over the heatsink where it is now plus it's getting heat from the other MTX running my fronts which isn't being stressed nearly as much.

Frank

bitches ain't shit but hos and tricks.

Mine is mounted in the same spot and I have the same problem. One of these days I'll probably mount a fan to it or something similar. I have considered going to d-class for stealth and/or less need for cooling.

Mine is mounted inside the rim of the spare tire, and I've had it overheat only on a road trip where the trunk was packed full and it was near 100* with direct sun.

Lick on these nuts and suck the dick.

Yeah, it doesn't overheat much, but it does occasionally - when it's hot out, a long drive - I think the diff and the exhaust aren't helping, and yes, it's at the top of the trunk. Maybe an exhaust vent? Could put a flip up license plate. :-)

The amp is 1200 watts, 5 channel - it might be overdriving the other speakers, but not the woofer, which like (I think) a 350 watt with 400 driving it, and it's never up all the way, I would die. :-) But it is when it's loud I have issues. I have a pair of 70 or 80 watt infinities in front and some 15 year old 35 watt pioneers by the gas tank to fill in the sound a bit, plus bose tweets in the doors.


I guess I should look at turning it down? It's certainly close as is, I'm not way overpowering anything except those pioneers, and they are turned down.

One more pic, just cause I like how the speaker came out:
http://abefm.smugmug.com/photos/513013659_qHUkf-L.jpg

wattage is relevant but not useful without the subs impedance ratings (and wiring if it's DVC).

360 watts @ 2 ohms; class-d sub amp ftw!

Put it on the floor. Obviously heat is not dissipating as effectively by having it on it's side. How about an amp rack w/ fans?

ok since abe will never answer me, he's probably overdriving it and it's overheating. probably is normally marginally OK, but as soon as it has no cold thermal sink, it's just getting too hot.

yeah - it doesn't really contact the rear wall much - its all convective/radiative.

Um, it's a woofer, DVC (2x4ohm in parallel), rated at 350W @ 2 ohms, and the amp is rated at 400 @ 2 ohms. I *can* double check the woofer specs, but I remember doing it before and thinking it was just right for the application, including the nice high cut-off frequency.

Maybe I need thermal straps! Actually, this is one case where I'd feel ok using fans... the amp is already marginal and has a safety, so if the fans fail I'm just back where I started.

But I really want to make a vent. Maybe through the tail lights? Something to just let the car moving provide the airflow (it's only ever overheated on the freeway)

TS-W306DVC - which is most likely 400w RMSm but might be 350 - there was a model change and I'm not 100% clear which spec is with which part. I don't think you can tell from the outside which is is, and I've yet to find any photos which show the label.

Like others have said, your amp, being upside down is trapping all the heat it makes. A TINY crossbreeze will probably fix it, just like mounting it right-side up so the heat can radiate out of the heatsinks. Heat goes UP.

You could try mounting it on the bumper side at a better angle, just let that heat go up.

the woofer rating is more of a "thermal guideline" than a power consumption value. if it's playing low enough in a small box and the volume is high enough, it'll draw more than the amp can put out. sounds like you just need more amp headroom.

Wow, I imagine not. It was a very tight squeeze - one I'm pretty happy with, all in all, since I did get 5 full channels of nice, independent, clean balancabe output for very little cash and even less space.


headroom meaning physical space, or you mean draw less power from it?

I think I'll see what a computer case fan or something similar can do for it, unless someone has some better suggestions for fannage. Much as I like the vent idea, I've kinda gotten no positive responses. The plastic feet on the thing (keeping it from making thermal contact at the mount point) did kinda bother me when I put it in. Having it mounted sideways probably wreaks havoc with the convection inside.

I cant believe so many of you ricers run subs in your trunks >:3

headroom as in draw the same power from more amp.

Well, don't think I'll be buying a bigger amp. The thing was really warm in my trunk today after 20 minutes. It just needs a fan. Will get on that, and report.

hell, even turning it so the fins run vertically will help a lot. natural convection doesn't go sideways you may recall.

But that amp is so goddamn big it's twice as tall as the trunk.

Just put some air on it and it should be fine. If you give it plenty of airflow it shouldn't overheat. If it does, then you've got bigger problems (like your amp is fucked up)

it'd probably be plenty cool if half of it was sticking out the top of the trunk :)

Ah, and we're back to venting. Not that I have any great ideas on it. I kinda like vents by the rollbar, but I would need exhaust, too. Maybe I should just pull the drain plugs. :-P

Any suggestions on fans? There are very few ways to mount that amp.

Update!
 

So, two things.

Three.

My deck sucks. The music would cut out on playing MP3's but not on the stereo. Then it stopped playing MP3's altogether, only making weird thumpy buzzy sounds.

So, I thought that was the issue, but no, the amp really was getting hot. I decided to try the scoop thing, and took the hose off my shopvac, put on a floor attachment and zip tied it to the roll bar. I looped it up, then put the other end in by the rollbar (tight fit) so it "blew" into the trunk. The radio didn't cut out once, but I never ran it very hard for very long, but it was super hot out so I think it's a sucsess. The previous night, driving to LA, when it was somewhat cold, the thing overheated all the time. It needs a pressure differential, I had both flaps open by the tank and it overheated many times till I turned the boost down.

Anyway, what I'm getting at is a fan in the unit will only move the hot air around. It'll help but not much. Airflow through the trunk will help shrink the boundary layer but also minimize the air temp.

Also, I really like the idea of ship's air intake scoops on a miata.

It does if you are cornering at over a G and hold it.

you're thinking of unnatural convection.

So why has no one designed me a scoop yet? I had to cut off the shop-vac-hose set up so I could put my roof up....