Rear Seats, Trunk Design & Setup | Fundamentals ?

[T Dot 10+ year member]

Rear Seats, Trunk Design & Setup | Fundamentals ?

im looking design my car system from the ground up, but have it professionally installed.

VEHICLE:

- 2k Volkswagen Jetta

- 4 door sedan

- 8 speaker stock system

- rear split fold seats

- doors are equipped with power windows

DESIGN:

- show & shine car

- amateur sound competitions [optional]

- ported enclosure

since the car will be a show & shine car, they system design must be astectically appealing. though i would like to have the option of entering amateur sound competitions, as shows often have booths for that now.

i would like the trunk to be designed in such as way, where it will be functional with the trunk open and also have optimum output. with this being said, the car needs to draw a crowd from the spl levels produced with the trunk open, and the doors as well. therefore a ported enclosure is prefered, with the subs and vent firing rearwards.

TRUNK SPECS:

- 13 ft³ [specs from vw.com]

- largest box design - 20 x 40 x 40 - HxWxD

[20 x 40 x 40] was used as the largest boxed design to give everyone a rough idea of the size of the trunk. there is alot more usable spaces along the sides, and rear of the trunk.

i was looking to shoe horn as many subs in the trunk as i can. as in the show scene you must have a 'wow' effect to your car. so the more subs in the trunk the better. i was looking to atleast go 12 - 18 inch subs. my enclosure of choice would be ported, for the simple fact of drawing crowds at show & shines. sealed enclosures can be a second option.

my trunk is equipped with lifts, so the whole trunk can be used without worrying about anything closing down on enclosures. the only downfall is that i must have access to my rear lights.

SUBWOOFER:

- JL Audio 12W7 or JL Audio 13W7

- Earthquake

JL Audio W7 series are my first choice, since they give me the best of both worlds [sq / spl]. i have an option of using earthquake for the simple fact that i can get them well below cost.

i am looking to atleast go 12 inches or bigger. the more subs in the rear, the better.

FUNDAMENTAL QUESTIONS:

TRUNK SEALING:

from reading the forums available online, i have read that you must seal off the trunk from the passenger cabin.

- how can i properly seal off the trunk from the passenger cabin?

ive seen people use plexiglass to seal off the access from the rear fold down seats. that would probably be my first option, as it will look the best.

- how can i properly seal off the rear parcel self, or is this really necessary?

- if this is necessary, can i weld off the little holes in the rear parcel shelf?

- would this be an effective way of sealing?

- what are my other options for sealing the rear parcel self?

another question comes to mind, if i do seal off completely, how does the sound eminate from the trunk into the passenger cabin? wont sealing off produce less sound in the cabin?

ENCLOSURE DESIGN:

lets say i choose sub "X" from JL Audio, and its specs are as follows

Sealed Enclosure:

24x24x24

now if i designed a box with the same volume, but different spec, how would this effect the sound of the sub? for example, if the box was designed as 12x12x48 intead of 24x24x24

now say sub "X" is recommended with an enclosure of

RECOMMENED:

12x12x12 --> 24x24x24

what would the benifits of going 24x24x24 as opposed to 12x12x12?

if i choose a 12W7 or 13W7 speaker and fired them upwards, how far must them be from the upper wall of the trunk?

if i designed 2 or more boxes in the trunk [ie 1 sealed and 1 ported], would this effect the sound in any way, if so how? better yet, is it better to design 1 big box for everything?

I will be adding some pictures for reference...

Thanks

Click to read more...

 

[dbhittin 5,000+ posts]

people will say that earthquake sucks and i bet maybe 2 people here might of heard them, and im one of them and i used to run them. If ur gonna do earthquake, run the magmas. There awsome sounding subs and get hella loud. So since u can get a deal, i say run 4 of those.

 

[T Dot 10+ year member]

people will say that earthquake sucks and i bet maybe 2 people here might of heard them, and im one of them and i used to run them. If ur gonna do earthquake, run the magmas. There awsome sounding subs and get hella loud. So since u can get a deal, i say run 4 of those.

can i see pics of your setup? do you have the magmas?

thanks

 

[helotaxi 5,000+ posts]

TRUNK SEALING:
from reading the forums available online, i have read that you must seal off the trunk from the passenger cabin.

- how can i properly seal off the rear parcel self, or is this really necessary?

another question comes to mind, if i do seal off completely, how does the sound eminate from the trunk into the passenger cabin? wont sealing off produce less sound in the cabin?

Unless you are doing an infinite baffle setup, and you aren't, this is not necessary and as you said in the last line it will mean less sound in the cabin. Now if you were doing an all out SPL setup (in car SPL not out of car) you would want to seal the trunk off from the rest just to minimize the volume of air in the cabin, but you would still have the subs and ports firing into the cabin. For your setup, don't worry about sealing the trunk off.

Things I would worry about if I were you:

Sound Deadening. Use a lot of it. Everywhere. Gut the interior and put it on every metal panel. Get rattle pads and put them on every trim panel.

Electrical system. Upgrade the alternator. Use at least 1/0 cable for your main power cable. Add at least one battery in the trunk. Since it sounds like you will be playing the system with the car parked and engine off, invest a few good AC/DC power supplies. Cascade Audio makes some and I am sure there are other companies as well. Being able to plug the car into the wall will be a godsend at shows.

Appearance. The install will make or break the system, and not just in the trunk. Cosmetically integrating the entire system be it hiding or highlighting components is crucial on a shine car. If you want to do it right it is going to cost, big time. Find a good installer. Attention to detail is huge as I'm sure you already know. Make sure components match. The often overlooked stuff like wiring and power components can really add a lot to the visual appeal of the system. Line up visible screw heads. Consider plating or painting visible screws to match other components. Have amps, processors, and, if you are going all out any visible woofer baskets color matched. Decide on an overall theme/scheme and then find components that will fit that theme with minimal mods. The folks on this board can help you with specific choices once you have decided what look you are going for; i.e. if you were going a carbon fiber theme the Elemental Designs cones could be used to integrate the install with the look of the rest of the car.

 

[T Dot 10+ year member]

Unless you are doing an infinite baffle setup, and you aren't, this is not necessary and as you said in the last line it will mean less sound in the cabin. Now if you were doing an all out SPL setup (in car SPL not out of car) you would want to seal the trunk off from the rest just to minimize the volume of air in the cabin, but you would still have the subs and ports firing into the cabin. For your setup, don't worry about sealing the trunk off.

by this you mean IF the subs would be mounted in the rear parcel self, i would need to seal the trunk off... is this correct?

Sound Deadening. Use a lot of it. Everywhere. Gut the interior and put it on every metal panel. Get rattle pads and put them on every trim panel.

check, i will be putting atleast 2 layers of extreme dynamat. would i need to do anything with the roof as well?

Electrical system. Upgrade the alternator. Use at least 1/0 cable for your main power cable. Add at least one battery in the trunk. Since it sounds like you will be playing the system with the car parked and engine off, invest a few good AC/DC power supplies. Cascade Audio makes some and I am sure there are other companies as well. Being able to plug the car into the wall will be a godsend at shows.

would the battery really need to be in the trunk? i can probably retro fit 2 batteries in the hood, with a custom mounting plate. all i would need to do is relocate the air intake, which is not a problem.

Appearance. The install will make or break the system, and not just in the trunk. Cosmetically integrating the entire system be it hiding or highlighting components is crucial on a shine car. If you want to do it right it is going to cost, big time. Find a good installer. Attention to detail is huge as I'm sure you already know. Make sure components match. The often overlooked stuff like wiring and power components can really add a lot to the visual appeal of the system. Line up visible screw heads. Consider plating or painting visible screws to match other components. Have amps, processors, and, if you are going all out any visible woofer baskets color matched. Decide on an overall theme/scheme and then find components that will fit that theme with minimal mods. The folks on this board can help you with specific choices once you have decided what look you are going for; i.e. if you were going a carbon fiber theme the Elemental Designs cones could be used to integrate the install with the look of the rest of the car.

as for hiding components, would it be recommended to put amps under the dash, or seats for a stealth look?

can you please post up the website for elemental design?

thanks

 

[helotaxi 5,000+ posts]

by this you mean IF the subs would be mounted in the rear parcel self, i would need to seal the trunk off... is this correct?

Typically infinite baffle setups in the car mount the subs either in the rear shelf or on a baffle behind the rear seats. The trunk acts as the "enclosure". In this type of setup it is vital to make sure the trunk is sealed from the cabin of the car, but this is NOT what you want for a show type setup.

check, i will be putting atleast 2 layers of extreme dynamat. would i need to do anything with the roof as well?

If it was me, yes. Deaden the roof as well.

would the battery really need to be in the trunk? i can probably retro fit 2 batteries in the hood, with a custom mounting plate. all i would need to do is relocate the air intake, which is not a problem.

That will work.

as for hiding components, would it be recommended to put amps under the dash, or seats for a stealth look?

I was not suggesting that you hide anything necessarily. Having the amps integrated into the theme of the trunk or somewhere else in the car can really add to the visual impact. If you really want to turn heads, you will have to come up with something unique. Wherever you mount the amps, make sure they have adequate ventilation so they do not overheat.

can you please post up the website for elemental design?
thanks

Elemental Designs

 

[T Dot 10+ year member]

Typically infinite baffle setups in the car mount the subs either in the rear shelf or on a baffle behind the rear seats. The trunk acts as the "enclosure". In this type of setup it is vital to make sure the trunk is sealed from the cabin of the car, but this is NOT what you want for a show type setup.

i understand that now. thanks

If it was me, yes. Deaden the roof as well.

would i run into any problems since the car is equipped with a sunroof. the glass also comes into the car, and slides back, unlike other cars where the slide outside the car.

I was not suggesting that you hide anything necessarily. Having the amps integrated into the theme of the trunk or somewhere else in the car can really add to the visual impact. If you really want to turn heads, you will have to come up with something unique. Wherever you mount the amps, make sure they have adequate ventilation so they do not overheat.

what are the proper / common locations where amps are supposed to be mounted and located? im am still trying to come up with a location, but have yet to decide.

the main reason why i want to hide the amps, is due to the fact the car has a very clean look. therefore i would like to follow the same concept in the trunk as well, i do not what the trunk to be over 'dressed' so to say.

thanks

 

[PopcornPlaya 10+ year member]

you could do an amp rack behind the folding seats, where if you want to show them, you simply fold the seats down. and when you dont want them seen, fold the seats back up.

 

[helotaxi 5,000+ posts]

would i run into any problems since the car is equipped with a sunroof. the glass also comes into the car, and slides back, unlike other cars where the slide outside the car.

That should actually be better than the outside kind and much better than a moon roof.

what are the proper / common locations where amps are supposed to be mounted and located? im am still trying to come up with a location, but have yet to decide.
the main reason why i want to hide the amps, is due to the fact the car has a very clean look. therefore i would like to follow the same concept in the trunk as well, i do not what the trunk to be over 'dressed' so to say.

You are working with goals that are somewhat conflicting. You can have "really loud" or you can have "hidden." The amount and size of gear required to get loud will not be able to be hidden.

Well, you mentioned the possibility of giving up the whole trunk, so dressing it up will be something of a must. Now you can make it pretty subdued looking and not flashy, but with the whole trunk full of audio gear, it will not be subtle.

Just some ideas:

4 subs in an enclosure in the front of the trunk with two mounted normally firing up and two mounted inverted (basket and motor structure outside the box) on an angled face facing into the rear portion of the trunk. Amps mounted in a raised false floor in the rear portion of the trunk under glass with fan cooling. If you have undercar neon/leds you can accent the amp in the same color lighting.

Mount two subs inverted in an enclosure in the front of the trunk. Build a removable "wall" to hide the subs from view from the rear. Build an amp rack into the rear package shelf with a removable cover and fan cooling.

I have seen amp racks built into the backrests of front seats, the backrests of rear seats, the cushion portion of rear seats, recessed into the passenger and driver footwells, the roof, the center console, the rear quarter panels (on a 2-door), just about everywhere. The keys are imagination, a willingness to cut/fabricate and having a plan to wire and cool the whole thing.

 

[bri487 5,000+ posts]

people will say that earthquake sucks and i bet maybe 2 people here might of heard them, and im one of them and i used to run them. If ur gonna do earthquake, run the magmas. There awsome sounding subs and get hella loud. So since u can get a deal, i say run 4 of those.

i had some problems with earthquake amps overheating and dumb things like that.

 

[dbhittin 5,000+ posts]

i had some problems with earthquake amps overheating and dumb things like that.

talking about the subs, not amps. I know the amps aren't the greatest, but there subs are pretty **** good if u ask me. id run a pair over the HC's

 

[T Dot 10+ year member]

you could do an amp rack behind the folding seats, where if you want to show them, you simply fold the seats down. and when you dont want them seen, fold the seats back up.

- thanks for the tip, that is one of the many locations i might consider

 

[T Dot 10+ year member]

That should actually be better than the outside kind and much better than a moon roof.

- sorry if it wasnt worded properly, but my question was regarding sound deadening. would it be harder to sound deaded, since i have a sunroof?

You are working with goals that are somewhat conflicting. You can have "really loud" or you can have "hidden." The amount and size of gear required to get loud will not be able to be hidden.

Well, you mentioned the possibility of giving up the whole trunk, so dressing it up will be something of a must. Now you can make it pretty subdued looking and not flashy, but with the whole trunk full of audio gear, it will not be subtle.

- as mentioned above, i would like most of the audio gear to be hidden. not all of it needs to be hidden. i guess the non conforming items like the batteries and other 'ugly' items i think would not go with the flow of the car.

Just some ideas:

4 subs in an enclosure in the front of the trunk with two mounted normally firing up and two mounted inverted (basket and motor structure outside the box) on an angled face facing into the rear portion of the trunk. Amps mounted in a raised false floor in the rear portion of the trunk under glass with fan cooling. If you have undercar neon/leds you can accent the amp in the same color lighting.

- could this be accomplished with the jl audio w7 series subs? i have yet to see a design with the basket and motor outside the box. on that note, i do like your ideas, as the are 'outside the box' [no pun intended].

Mount two subs inverted in an enclosure in the front of the trunk. Build a removable "wall" to hide the subs from view from the rear. Build an amp rack into the rear package shelf with a removable cover and fan cooling.

- that too, is also a great idea. would there be excess rattling of the rear parcel self since the subs are directly under? also could you please post up links where i can see and purchase cooling fans.

I have seen amp racks built into the backrests of front seats, the backrests of rear seats, the cushion portion of rear seats, recessed into the passenger and driver footwells, the roof, the center console, the rear quarter panels (on a 2-door), just about everywhere. The keys are imagination, a willingness to cut/fabricate and having a plan to wire and cool the whole thing.

- i think i might have some more of the 'crazier ideas', i just need to know it would really work so to say. i love the idea of using the front seats too, but that would only work if i keep the oem seats. in regards to the passenger and driver footwells, is there a way to keep them fiarly clean, but also have them vented for cooling?

thanks again for all you ideas and tips

 

[T Dot 10+ year member]

talking about the subs, not amps. I know the amps aren't the greatest, but there subs are pretty **** good if u ask me. id run a pair over the HC's

he is correct, i was talking about their subs. sorry if i wasnt more clear about that.

 

[helotaxi 5,000+ posts]

- sorry if it wasnt worded properly, but my question was regarding sound deadening. would it be harder to sound deaded, since i have a sunroof?

Is it a metal sunroof? If so, deaden it, too.

- as mentioned above, i would like most of the audio gear to be hidden. not all of it needs to be hidden. i guess the non conforming items like the batteries and other 'ugly' items i think would not go with the flow of the car.

Batteries are hard to make look good, but all the other components are very easy to integrate into a theme and create a smooth, clean look.

- could this be accomplished with the jl audio w7 series subs? i have yet to see a design with the basket and motor outside the box. on that note, i do like your ideas, as the are 'outside the box' [no pun intended].

The problem with the W7's in this type of setup is they want quite the large box. The box would take up so much of the trunk that there would be almost no room for the sub to be inverted and they need a lot of room themselves, these subs are physically HUGE. From the show coverage I have seen, inverted mounting is pretty common on the show scene, at least the car audio show scene.

- that too, is also a great idea. would there be excess rattling of the rear parcel self since the subs are directly under? also could you please post up links where i can see and purchase cooling fans.

That's what the sound deadening is for. Also when you build the amp rack, it will strengthen and help deaden the shelf further. Radio Shack sells 12 volt fans you can also look at Parts Express

- i think i might have some more of the 'crazier ideas', i just need to know it would really work so to say. i love the idea of using the front seats too, but that would only work if i keep the oem seats. in regards to the passenger and driver footwells, is there a way to keep them fiarly clean, but also have them vented for cooling?

The best solution I have seen is building the amprack actually under the car with a glass (real tempered glass because it doesn't scratch as easily as plexi or Lexan) window over it and using the floor mats to hide it when not being shown. This type of setup requires fan cooling and under the seats is the best place for the fans to vent.

If you have ideas, figure out a way to make them work. Anything is possible. Anything. All you need is a good fab guy and a lot of creative thinking to turn your ideas into the final workable product.