mounting subs in the rear deck not an option, custom box design? will this work?

[macantley]

Typically i prefer cutting out the rear deck of a car and mounting the subwoofers in the rear deck so the bass is reflected off the back glass and all the sound is kept in the cabin for sound quality purposes, i really dislike having the subs fire into the trunk, i really dont want to if i dont have to, so im trying to come up with a good box design for my 2004 infiniti G35 sedan but the largest i can cut on the rear deck is approx 31.25" wide by 6.25" front to back without doing any structural damage.

my old car i was able to mount two american bass VFL 12's in the rear deck, however that doesnt seem possible with the new car so i came up with this design that im curious about the subs im using are infinity kappa Perfect 10.1 subs, i can run them in .6 CF sealed, or i can slot port the box and run them approx. 1.5 CF per sub slot ported, i dont mind running the subs either way, sealed is easier, but slot ported will produce a "fuller" sound However im not sure if this box design will even work, i dont want it to sound like a band pass box, but i think with a port approx 30" by 5" (after factoring in wood dimensions) anyway here is box design #1 , please let me know if this even looks like it would sound fine.



here is design #2 , my only concern is the subs reflecting off the wooden wall would produce poor sound waves, please let me know if this will work.



and i realize that design #2 will not permit a ported enclosure, but design #1 will probably not be ported either.

please give me some suggestions as to how i can do this, keep in mind that the LARGEST opening i can make is 30" x 5" in the rear deck after factoring in the dimensions of the MDF

matthew

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[Chriszle 10+ year member]

Do you have a ski hole in the back seat? If so, why not do a 4th order, and port through that? Otherwise a 4th or 6th order ported through the rear deck?

 

[macantley]

dont want band pass for sound quality purposes, ive never liked the "boomy" sound of band pass boxes. the Ski hole is only about 4" x 7" also. if i was doing band pass, id use the stock 8" subwoofer hole to port through.

 

[ladysmanfelpz 10+ year member]

I have a similar dilemma. I don't want to have a sub in my trunk of my 07 accord coupe because I prefer the bass in the cabin as well. I was thinking of just doing some CDT 6x9 subs in my rear deck. IB will let me get pretty low and with a eq I can get it to sound near a ported box. Do you think it is possible to fab up a small box out of like 1/2" mdf that hangs from the rear deck?

 

[chefzane]

Wow you guys, just wow, just build a slim box and seal the trunk off from the cabin at the baffle face

 

[Jeffdachef 5,000+ posts]

dont want band pass for sound quality purposes, ive never liked the "boomy" sound of band pass boxes. the Ski hole is only about 4" x 7" also. if i was doing band pass, id use the stock 8" subwoofer hole to port through.

thats a misconception. A 4th order when done right can have amazing sound quality and bandwidth just too many people going for the boom factor. My 4th order box is geared for SQ and its very flat and digs deep into the lows.

 

[macantley]

by the way i dont want to hear any negative comments on my question, alot of people who have nothing better to do just think im nuts, Here's a photo of the last car i had, it is the box in a 2002 nissan maxima with two american bass VFL subs at 1.75 CF of airspace sealed (should have ported it with that much air space) so dont think im not serious about the deck, ive done it before and the sound quality of using the deck is absolutely amazing!



that being said, ive ruled out cutting the deck on this car, its just not possible, the stock 8" subwoofer has been removed and hopefully the sound from the trunk will go through the 7.25" hole that the 8" woofer was mounted in, there were also two vents on each side of the rear deck that should allow the waves to pass through, the back of the rear seats are so well insulated and dont lay down that i dont think there will be much help in letting the waves go that way, its going to have to pass through the deck. Once i can afford to, i will be sound deadening the entire trunk and rear deck.

 

[SounDrive Pro Seller]

by the way i dont want to hear any negative comments on my question, alot of people who have nothing better to do just think im nuts, Here's a photo of the last car i had, it is the box in a 2002 nissan maxima with two american bass VFL subs at 1.75 CF of airspace sealed (should have ported it with that much air space) so dont think im not serious about the deck, ive done it before and the sound quality of using the deck is absolutely amazing!


that being said, ive ruled out cutting the deck on this car, its just not possible, the stock 8" subwoofer has been removed and hopefully the sound from the trunk will go through the 7.25" hole that the 8" woofer was mounted in, there were also two vents on each side of the rear deck that should allow the waves to pass through, the back of the rear seats are so well insulated and dont lay down that i dont think there will be much help in letting the waves go that way, its going to have to pass through the deck. Once i can afford to, i will be sound deadening the entire trunk and rear deck.

Do a properly designed 4th order with the port firing through the rear deck... Unless your rear seats fold down, then fire the subs and port forward and seal off the trunk. The second option is what I'm currently doing in my car and it sounds better and gets louder than a regular trunk build.

 

[macantley]

ok, i have to admit, im now curious about the bandpass box design and possibly porting it through the ski hole, or the now removed 7.25" sub hole in the rear deck, im very poor at box specs though, i can build about anything, work with fiberglass, (when time permits) but my volume design is very lacking.

what i read about 4th order is:

my subs require .6 cubic feet sealed, so if i run the sealed part of the box at .6 cubic feet per sub, the chamber they fire into will be 1.2 cubic feet per sub, im pretty sure i have that kind of space so that probably wont be an issue, HOWEVER i have no idea how large/long the port will need to be for proper SQ, i dont want boomy single frequency sound, i want to hear my notes, i can probably enlarge the port to as large as an 8" square, but i dont know how large/long of a port i should have.

anyone got any suggestions?

matthew

 

[itsblown 10+ year member]

pay for a design from someone on the forum in the vendor section

 

[macantley]

using scrap wood today (some old 3/4" plywood) i mocked up a rear firing trunk box in a shape i can live with, what i came up with was that i could have as much as 3CF of airspace, while id love to run 4 of the infinity kappa perfect 10.1 subs, i dont have 4 of them, i only have 2, so my choices are limited.

i can cut the box down in size some because the woofers only require .60 CF each, or i can use the full 3CF of airspace and go ported, the box is roughly 37x16.5x8.5 internally, the 8.5 is the front/back depth, But im not sure if 3CF is enough airspace to really port the woofers, anyone else want to chime in on porting? infinity claims that the subs require 1CF each ported, so would that mean that the entire length of the port for each woofer should use up .50 CF?

matthew

 

[Jroo 10+ year member]

Im looking at both pics you have above and they both seem like they would have some form of "bandpass" effect to them. It looks like each sealed sub is firing into something before escaping the rear deck. In both cases what they are firing into, would have almost the effect of a second enclosure which would be similar to a bandpass.

Ive used several bandpass boxes over the years and they certainly can be SQ suited if designed the correct way. Most of my boxes but not all had larger sealed sections and in many cases much smaller ported sections with much higher tunings (60 and 65 hz). bandpasses get a bad rap because many of the designs people hear were done to be loud a **** and are often peaky, which I guess is good for guys looking for SPL. A good designed 4th order should have a very similar curve as the sub in a sealed box but should be louder through that response curve. Also throw out these ratios that people randomly tell you. You will hear 1:1, 2:1, 3:1 and so on. Basically model it, play with it, and change it to your liking. The last box design I had ended up being close to 2:1 but the sealed side was larger than the ported side, which is the opposite of what most people tell you to do on a 4th order.

 

[DonH 5,000+ posts]

buy a driver IB capable and call it a day. build a IB baffle where the backs of the seats are.