Sub boxes in side of boot?

[frogsta]

I have 2 12" Alpine Type S (I think, might be R) subs, was wondering how I can get them mounted on opposite sides of my boot. I drive a VS commodore (dual fuel, if that matters).
Any audio specialists that'll do it in Perth? Also, can the amps be put under the boot carpet stuff?

[acarmody]

If your good with fibreglass you can make something like this, HOLDEN COMMODORE 12'' SUB SUBWOOFER BOX VX VT LS1 GEN 3 | eBay , or any (decent) car audio place can make them for you, just remember to take some lube with you when you ask the price

[frogsta]

Lol what? Any audio places in Perth/ audio places in general?

[acarmody]

LOL, it was a joke, custom fibreglassing will cost heaps unless they already have moulds to go on, which would be very unlikely. Its not that fibreglassing is hard, its just time-consuming.

A proper car-audio place would be best, but just ring around and ask who can do it, or if they can suggest a place that can.

[frogsta]

Fair enough, well I'm no good with handiwork so I'll just ring around and see what I can find, cheers.

[DAKSTER]

I have the same dilemma, this is what I see as the available options.

You can buy pods for the drivers side for a single 12" but the passenger side on a VS has the spare tyre where you want the pod to be.

To have one on either side of the car, you have to lose the spare wheel from the passenger side so you can install a pod there. You could make a false floor to hold the spare and the amps, but you obviously lose boot depth, and lots of it.

You could do without a spare, and keep a can of emergency spare goo and an auto club membership just in case. Then you could mount the amps on either side of the boot next to the pods for a cool look, and keep your boot depth. Going without a spare is not an option for me, but many people do it for the sake of a decent sub installation when they install subs in the spare tyre well on other models.

You could make do with a single 12" in a pod on the drivers side and leave the rest unchanged.


I've yet to investigate the potential problems with putting subs up with the gas tank, but I intend to as I see it as the best option if it can be pulled off.

With gas, behind the seats is the most problematic option. I've considered making a false panel to conceal the gas tank, and using a bunch of dynomat (even on the tank itself I presume) maybe mount a couple of subs on spacers behind that panel.

The reason I am considering spacers is to allow the box to be sealed ( an unported system suits my musical taste ), but have the speakers a couple inches behind the actual hole in the panel. Thats because I am considering simply using crimsafe on the outer of the panel to protect the speakers, and want to allow plenty of room for speaker travel. The crimsafe could cover the entire panel, that would look pretty tidy IMO.

Heres a couple acoustic questions for our audiophiles..

I never see subs behind reasonably fine mesh grilles. Is this for cosmetic or acoustic reasons?

Would using a finer mesh such as crimsafe make any difference acoustically? I just want to protect the speakers more effectively from the contents of the boot, I have no interest in displaying the speakers as such. I just want them to sound good without taking my boot away.

Would having a sealed metal cylinder (the gas tank) inside a speaker box ( wrapped in dynomat of course ) have any serious effect acoustically? I'm imagining the tone changing as the tank empties lol..

Do we need to separate one side from the other, or are both speakers comfortable in the same effective enclosure?

I'm aware none of this is ideal acoustically but is any part of it bad enough to be a real problem? I dont intend entering any sound-offs in the forseeable future, and I can live with minor compromises in sound quality, just so long as I get that nice crunchy kick when the big drums come into play.

Heres a couple questions for our LPG fitters..

Legally, can we hide the gas tank behind a panel provided we have a quick release access hatch to the gas valves and suchlike? Are there other reasons not to?

Is the mildly pressurised (by unported subs) box we create around the gas cylinder a problem? Or do we need to have a venting system of some sort?

Is wrapping the tank in dynomat a problem?

Is vibration a potential problem?

If all of these questions can be resolved, then wewould lose a pretty small amount of our boot with the spare where its meant to be and no pod on the drivers side. This would mean we could keep most of that excellent deep VS boot in its original form pretty much, just losing a little more at the front than the gas tank already takes.

If that doesnt fly, and I suspect there will be legal issues, I will go with a single pod and sub. I love the huge deep boot of the VS, the false floor or going without a spare options dont appeal to me, and a dirty great sub box sitting in the middle of the boot isnt going to happen either.

[GRPABT1]

I don't use a spare or tyre go or have auto club membership, seriously how often do you have a flat? I've had 1 in ten years. Everyone has a mobile phone these days, keep the spare at home and call in a favor to get a lift to pick it up if you ever need to. Unless you drive rural or vast distances I wouldn't worry about the spare.

[MAG00]

I have the same dilemma, this is what I see as the available options.

You can buy pods for the drivers side for a single 12" but the passenger side on a VS has the spare tyre where you want the pod to be.

To have one on either side of the car, you have to lose the spare wheel from the passenger side so you can install a pod there. You could make a false floor to hold the spare and the amps, but you obviously lose boot depth, and lots of it.

You could do without a spare, and keep a can of emergency spare goo and an auto club membership just in case. Then you could mount the amps on either side of the boot next to the pods for a cool look, and keep your boot depth. Going without a spare is not an option for me, but many people do it for the sake of a decent sub installation when they install subs in the spare tyre well on other models.

You could make do with a single 12" in a pod on the drivers side and leave the rest unchanged.


I've yet to investigate the potential problems with putting subs up with the gas tank, but I intend to as I see it as the best option if it can be pulled off.

With gas, behind the seats is the most problematic option. I've considered making a false panel to conceal the gas tank, and using a bunch of dynomat (even on the tank itself I presume) maybe mount a couple of subs on spacers behind that panel.

The reason I am considering spacers is to allow the box to be sealed ( an unported system suits my musical taste ), but have the speakers a couple inches behind the actual hole in the panel. Thats because I am considering simply using crimsafe on the outer of the panel to protect the speakers, and want to allow plenty of room for speaker travel. The crimsafe could cover the entire panel, that would look pretty tidy IMO.

Heres a couple acoustic questions for our audiophiles..

I never see subs behind reasonably fine mesh grilles. Is this for cosmetic or acoustic reasons?

Would using a finer mesh such as crimsafe make any difference acoustically? I just want to protect the speakers more effectively from the contents of the boot, I have no interest in displaying the speakers as such. I just want them to sound good without taking my boot away.

Would having a sealed metal cylinder (the gas tank) inside a speaker box ( wrapped in dynomat of course ) have any serious effect acoustically? I'm imagining the tone changing as the tank empties lol..

Do we need to separate one side from the other, or are both speakers comfortable in the same effective enclosure?

I'm aware none of this is ideal acoustically but is any part of it bad enough to be a real problem? I dont intend entering any sound-offs in the forseeable future, and I can live with minor compromises in sound quality, just so long as I get that nice crunchy kick when the big drums come into play.

Heres a couple questions for our LPG fitters..

Legally, can we hide the gas tank behind a panel provided we have a quick release access hatch to the gas valves and suchlike? Are there other reasons not to?

Is the mildly pressurised (by unported subs) box we create around the gas cylinder a problem? Or do we need to have a venting system of some sort?

Is wrapping the tank in dynomat a problem?

Is vibration a potential problem?

If all of these questions can be resolved, then wewould lose a pretty small amount of our boot with the spare where its meant to be and no pod on the drivers side. This would mean we could keep most of that excellent deep VS boot in its original form pretty much, just losing a little more at the front than the gas tank already takes.

If that doesnt fly, and I suspect there will be legal issues, I will go with a single pod and sub. I love the huge deep boot of the VS, the false floor or going without a spare options dont appeal to me, and a dirty great sub box sitting in the middle of the boot isnt going to happen either.

Acoustically, the mesh should be no problem. People put mesh and speaker cloth over their speakers all the time. The grills that came with my mid-woofers were very crimsafe like mesh.

In regards to the gas tank, as long as the emergency cut off is reachable then you should be fine. Contact your local authorities for further details.
Also, with the gas tank, think of it this way; those gas tanks are built to withstand a car accident so that they do not burst and cause havok, a little bit of bass won't hurt. You MAY have issues with subwoofer magnets affecting the fuel level gauges, and the bass wobbling the fuel around giving slightly incorrect readings on your fuel gauge, but it's highly unlikely.

Also, I had trouble understanding what you want to do. You want to seal the gas tank into the box? Or just have a box up against it? Acoustically there is no issue with the box being infront of the tank, if you for what ever reason built the box around the tank, with the tank in the actual box, then it may affect the back wave distortion etc.
I wouldn't worry about dynamatting the tank, those things by rights should be thick and have a low resonating frequency as is, adding dynamat would be a moot point.

[DAKSTER]

I am hoping to divide the front section of the boot, ie the shelf behind the seat where the gas tank is located, from the rest of the boot with a wooden panel. This should create an enclosed space, with a gas tank inside it. This enclosed space would become my speaker box.

It means the sound waves wont move around the box the way they should I am assuming, because although the box will have sufficient air volume it will be the gaps around the tank that provide that air volume. It also means that if I install 2 subs, they are sharing the same air volume unless I also somehow install a divider around the tank. This will be a sealed, not ported, box.

I know all this isnt ideal acoustically, but will it give a reasonable bass without sounding too terrible? Not out to win any soundoffs, just want to give the bass some extra punch.

[MAG00]

Good luck sealing that. Also, far from ideal acoustically. Also, could damage your subs if it is too big of a space for them to handle (lack of air pressure in the box etc.)

Ideally, there should be no sound waves within the box. These waves from the back of the subwoofer (in the box) are 180 degrees out of phase with the sound waves coming from the front of the woofer. These cancel some of the front waves, affecting sound quality and output.

Could work, you could just go with corner enclosures or some 6x9s if this works out too hard.

[DAKSTER]

Thanks for your help

My apologies to the OP, I am not trying to hijack your thread.. we just have identical situations and hopefully any information or ideas that are offered here are just as useful to you as they are to me... the combination of the side mounted spare wheel and the gas tank, and the desire to have a usable boot, provide us with a slightly unusual situation compared to most.

I hope to get the dividing panel as close to the gas tank as possible, and basically using the void space around the tank as the box. I was actually concerned that there wouldnt be enough air volume rather than there being too much. Looking at pods with 30 litres of air volume for a 12" sub, I am again just making an assumption that I would need about 60 litres of air for 2 of them, and I would be surprised if my 'box' would have that amount of total capacity with the tank taking up most of the middle of it.

I may be using the wrong terminology when I say sound waves, I dont know, but what I mean is that I know speakers are designed to have waves/pressure/air movement or whatever move around the box in a particular way. I am just wondering just how important that particular feature is, or is the actual volume of air more important than the internal shape of the box?

I dont know about the OP's sound requirements but I dont need major subsonic vibration like the modern music, I just want solid clear crisp rock n roll. Punch rather than rumble for me (ACDC, Fleetwood Mac, Dire Straits), though of course if Chris Brown and Rihanna also came up well with it my kids would be happier..

I was also concerned that the subs may not work well if they share the same air volume.. I'd heard of the cancelling effect you are speaking of, and wondered if they could also cancel or interfere with each other in some way. Dividing the airspace with a cylinder in the middle of it would be a more difficult carpentry job though so if they arent going to make a major difference to each other that would save me that particular task.

I know I wont get the area completely airtight, but I should be able to seal it off well enough to perform the function well enough? I'm thinking the amps could go on the speaker side of the panel too, effectively meaning the amps would be actually inside the speaker box. Is that an issue?

[frogsta]

Hahaha it's all good, I've been having the gas tank in the boot with my subs, just leaves barely any room. As far as acoustics, my box is just sitting there, but it doesn't seem to be any less loud due to the gas tank. So do you know any good places to go to for the side boxes? Cheers.

[Not_An_Abba_Fan]

and the bass wobbling the fuel around giving slightly incorrect readings on your fuel gauge, but it's highly unlikely.

How would the bass affect the fuel INSIDE a tank? Bass, in fact all sound for that matter, is just air pressure waves. Air pressure waves cannot affect anything inside a sealed tank. The only affect it would have is from vibrations from the boot it is bolted to, but just general driving causes more fuel movement than bass ever could.

[MAG00]

How would the bass affect the fuel INSIDE a tank? Bass, in fact all sound for that matter, is just air pressure waves. Air pressure waves cannot affect anything inside a sealed tank. The only affect it would have is from vibrations from the boot it is bolted to, but just general driving causes more fuel movement than bass ever could.

Was just giving worse case scenarios, obviously the actual sound waves will not affect the tank, but the vibrations may have some effect. If you read it closely I was very hesitant to even suggest possible issues involving subs and gas tanks

[DAKSTER]

Hahaha it's all good, I've been having the gas tank in the boot with my subs, just leaves barely any room. As far as acoustics, my box is just sitting there, but it doesn't seem to be any less loud due to the gas tank. So do you know any good places to go to for the side boxes? Cheers.

If they are in boxes or pods then no, the gas isnt an issue acoustically. The reason I was asking about that is that in my plan, the gas tank is effectively inside the speaker box, so I thought that might have an acoustic effect.

The fibreglass pods you are talking about are available on ebay. You can get them for the driver side to suit a 12" sub in a VS, but since you have a spare wheel in the way on the passenger side, I think you are going to find it hard to find one for the passenger side. If thats the way you want to go, you may have to stick with a single sub on the drivers side. Thats my backup option if my current thoughts turn out bad..

[wrx884]

i always recommend FreeDB in freo and they r not far from u, speak 2 Micheal or his son.

[frogsta]

Alrighty cheers guys, 'sounds' good. Eheh.. oh, and with it affecting LPG readings it could be plausible. I'm assuming it checks how much gas is left by pressure in the tank, and really loud music generally alters that pressure. Wouldn't be a big difference though.

Edit: Also, just checked the address on FreeDB. Was at the hospital the other day, and walked there. Was quite nice, at least I know the place is good now.