sliding sub

[Dan2]

just a quick question:

the sub in the trunk of my car always slides around when i drive- and i have the amp screwed onto the back of the box so its starting to do some damage to the wires.

so whats the best way to secure the box - bearing in mind that i need to take the carpet out to get to the spare wheel.

 

[speaker]

Ideally, the sub is secured to the body of the vehicle or the seatback in a hatchback car with brackets & bolts. A few things are accomplished. The first is safety. Now, no bracket will hold a subwoofer entirely secure in a high speed crash but in a moderate one it should stay put. You certainly don't want it flying through the car. The second is also safety related. As you have the amplifier mounted to the enclosure, you don't want the high current +12VDC to come loose and spark around the back should it contact a ground point. The potential exists for a fire if it does. The last is bass output. If the subwoofer cabinet can move around, some of the bass output potential is lost. It will be more apparent with larger drivers and heavier cones however. Before you bolt anything down however, experiment with placement. You will find that some positions give you better bass and others lesser.

 

[Dan2]

Firstly - IF i have an accident, will the sub still be able to get into the cab if i have a sedan ('cos i do)??

second - i was thinking of bolting the enclosure down but then i wouldn't be able to get the carpet out to get to the spare. plus i would rather not put too many holes in the car.

i was also thinking of using something like velcro just to keep it in one place.

I am also concerned with the +12V wire - i have got a fuse on it at the battery but it does do a bit of sparking before the fuse blows

 

[speaker]

Firstly - IF i have an accident, will the sub still be able to get into the cab if i have a sedan ('cos i do)??

second - i was thinking of bolting the enclosure down but then i wouldn't be able to get the carpet out to get to the spare. plus i would rather not put too many holes in the car.

i was also thinking of using something like velcro just to keep it in one place.

I am also concerned with the +12V wire - i have got a fuse on it at the battery but it does do a bit of sparking before the fuse blows

I don't know if it will be able to get into the cab or not on your car. I have however seen personally a subwoofer enclosure that did tear through the rear seat and the front passenger seat when the car rear ended someone at ~30MPH. No one was in the passenger seat and no injuries occured.

I can't answer your second. Spare access may or may not be critical. I asked that question on vwvortex.com and was told that the way around it is to use Fix-A-Flat, spare tire in a can. Many of the VW's on that forum have false floors and the spare cannot be gotten to at all so they carry the canned air/sealant mix in place of a spare. The also will use the spare tire well as the enclosure itself.

I wouldn't use hook & loop myself. It will delay enclosure flight momentarily and that is about it. It will only be as strong as the carpet. If you can lift the carpet, the sub will fly.

I should point out that in the US, overwhelmingly people put a carpeted subwoofer enclosure in the trunk and call it a day. I am a bit paranoid in that regard and would have never given it a second thought were it not for seeing the spectacular damage a sub box caused when it flew forward. It was a dual 10", sealed enclosure with a total weight of ~50 lbs. maximum.

So.......your mileage may vary.

Good Luck!

 

[Clipped]

velcro works good

 

[jol50]

I have a 8" powered tube (but it is light) that I used in a few vehicles with velcro on the bottom feet. It worked great, but all it will do is keep your box from sliding and may not keep it from rolling over. What I would do is figure out how to put a strap on it maybe attached up on the wheel well or something. Kind of like a battery box in a trailer or in a boat. You could even screw a plate over a strap on back of box and then hook ends to car and tighten, etc. I have a small 10" box in one car right now just sitting there, but it is small/light and don't think it will fit through the smallish fold down seat opening either. It stays put, but is on a plug so I can take it out. The 4 12s in my other car have about a pound of screws holding them in and no box to move.

Another idea I have used is to put handles on the box, something like barn door/large door or cabinet handles/garage door pulls/etc. You can then strap through those to the car as well as carry box with them but they must be sturdy units.

 

[shagone]

i have used large strips of heavy duty velcro on a box with 2 10's and it stayed in place well but the carpet was secured to the floor. in some cars the carpet can move around and defeat the purpose. if that is the case you could secure the carpet first with spray adhesive or screws and be ok. in the long run it is always better to use some type of brackets to screw the box down firmly to the trunk.

also, i never reccomend having the amp mounted to the sub enclosure. not only can the wires come loose if the box slides but the bass will vibrate the parts in the amp and cause premature failure(i have seen it many, many times). i usualy mount my amps on a carpeted baffle board that is secured to the back of the seats or in the spare tire well in some cases with fans for ventilation.

 

[jol50]

Yeah, once you get into some power it will be hard on the amps. I have 3 class d amps here that are broken from vibration, nothing blew up. Some amps have more problems that others but with new amps it is much more common.

 

[shagone]

yup. especially the newer big class D amps. the parts on the boards are so heavy and they are not supported properly so they break the solder joint or the connection point from vibration. also, on some amps the heat sink mounted transistors are all that are holding the board to the sink and the legs often break because the boards are not supported properly underneath. i often add support under boards and on large board mounted parts to reinforce my repair jobs to be better than original. people are rough on amps so you can never be to safe.

 

[Dan2]

thanks for the advice i didn't even think of the amp breaking from the vibrations.

 

[jol50]

That is what I did with these, I supported the board and large parts better. In fact one is newer and they fixed some problems but not all. I could strap a pair for 2kw rms at 2 ohms....lol. I might try one at half speed, that would be enough for me except the large real estate they hog up is a big negative and I have smaller sized amps to use. I looked at a kenwood class d on the other hand and they appear screwed together pretty tight far as vibration issues. I have not had one, but others say the newer narrow amps like kicker and maxxsonics that stand the transistors upright on the sinks have issues breaking things as well. You can find a weak spot in near any amp, but nobody has told me yet what new amps they never see for repair. But those new amps are 1/4 the price of what the old ones used to be, or less. Back in the day I could buy 3 winter beater cars for the price of a new LP 300w amp.