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View Full Version : Tuning trunk car setup. Help?



KTMrida4life
01-10-2012, 04:24 AM
A few weeks ago I had RAM designs on here design me a box for 3 sundown SA 8s on 1800W rms. The box is 1.8ft^2 after displacements and has a slot port tuned to 33 hz.

Its pretty loud inside the car, but I'm almost positive that its probably 10db louder in my trunk. I know your going to lose some dbs from trunk to car, but not this many..

Heres why I think it should/can be louder. Folding down my rear seat does nothing to affect the loudness as far as I can tell. Besides that, I have some SERIOUS trunk rattle, and when I open my trunk, all the bass just goes out that way.. which it should the way its setup now, but if setup correctly as a loud trunk car, shouldn't it still be going into the car instead? Not 100% sure on that.. also, not to mention, I saw a video on youtube of a dude with 4 8s on 2k getting some serious flex in his car. His setup is different, but similar equipment. He has a 4th order box which I'm pretty sure I dont have room for unless assembled in my trunk. Heres a video of his..

Sundown SA-8s Bass Ballin - YouTube (http://www.youtube.com/watch?v=TVtA-Cepq60&feature=player_embedded)


Heres a really crappy vid of my setup I made a few days ago, Ill try to make a better one soon in the daytime.

http://a6.sphotos.ak.fbcdn.net/hphotos-ak-ash4/388263_10151129193345720_567885719_22169012_361154 68_n.jpg

Thats how the box is setup now. My trunk is TINY as you can see. Theres a massive hump in the front of my trunk right behind my rear seats that makes things rather difficult. You can see it here.

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-ash4/388867_10151129192885720_567885719_22169004_182817 7933_n.jpg


At this point, I've lost all my trunk space which is totally fine cause it keeps people from throwing their crap in my car, but I know there has to be a way to tune this setup better. I have another 8 Im going to recone very soon and would have to build another box for it, but I want opinions on what to do. What is all this about sealing off my trunk? How would I go about doing this? I see lots of people folding their rear seats down, which is fine, but I cant keep mine down all the time. That is silly, and my whole rear seat folds down as a unit, no 60/40 or anything. I can port through my rear speaker deck openings, but I've been told that sounds like crap by one person. Any other opinions on that?

KTMrida4life
01-10-2012, 02:09 PM
I dont know about porting through the rear speaker cutouts, but ive seen them port through the rear deck before and it looks to sound better than having all that trunk rattle. more output into the cabin, which is really the goal in your case correct?

Yes. Theres more boom in my trunk than in my car.

What do you mean porting through the rear deck? Like cutting out a big port in my rear deck? Im not going to modify mine.

basscort2009
01-10-2012, 02:16 PM
try changing the phase on the amp. if it gets louder with the trunk open while ur inside the car then its 100% out of phase.

hispls
01-10-2012, 02:32 PM
I suspect it is 10db louder in the trunk than in the driver's seat. Trunks are terrible in general and that looks to be particularly bad. Cutting out the rear deck and building into that, or bandpass ported in through there will be your best options for output, but certainly not simplicity. Really you should buy an SUV or hatchback

KTMrida4life
01-10-2012, 02:55 PM
try changing the phase on the amp. if it gets louder with the trunk open while ur inside the car then its 100% out of phase.
Yeah Ill try that.


I suspect it is 10db louder in the trunk than in the driver's seat. Trunks are terrible in general and that looks to be particularly bad. Cutting out the rear deck and building into that, or bandpass ported in through there will be your best options for output, but certainly not simplicity. Really you should buy an SUV or hatchback

Yeah I know, trust me, some day... I will have a much better car to work with. But this car is a 95 Nissan 240sx with less than 20,000 miles on it, and 7000 of those I put on it myself in the past 6 months. Its just broken in.

I'm considering learning how to work with fiberglass, and building my own box inside the trunk. If I did that I could probably fit 2 12s, but that would mean I would have to sell what I got.. which *****.

From what I've read, the problem is that the box isn't sealed off from the rest of the trunk, so bass goes whereever it desires. Theres no way to seal this particular box off.. but if I built a custom box right up against my rear seat (subs facing rear seat while its up) with aeros ported through my rear deck, then I could seal it off from the rest of the trunk. Im pretty sure that would be louder. I'll make a vid of my car again today.

ahole-ic
01-10-2012, 03:02 PM
The answer is simple yet so disappointing.....

KTMrida4life
01-10-2012, 03:14 PM
The answer is simple yet so disappointing.....

Are you suggesting a different car as well?

What happened to all the people on here that made things work in trunk cars? Buying a new car isnt something you just do for fun! lol -.-

basscort2009
01-10-2012, 03:15 PM
Best output for trunk cars are sub and port Foward sealed off from the trunk

double 07
01-10-2012, 09:13 PM
My trunk setup slams just fine!!!!26529815


I had to modify my rear deck between the 6.5" a little to let the sound into the car but my single Havoc 12" flexes all four doors...

KTMrida4life
01-10-2012, 10:15 PM
My trunk setup slams just fine!!!!26529815


I had to modify my rear deck between the 6.5" a little to let the sound into the car but my single Havoc 12" flexes all four doors...

So it looks like your subs and port back.

I flipped my box around tonight, so now its at the very back of my trunk subs/port facing drivers seat. Its much louder with the seat down.

So heres what I want to do.

-I want to fit my 4th SA 8 in my cars trunk SOMEHOW.. but I cant build a box big enough that will fit UNLESS I use some sort of external port. Unless I built the box in the trunk.
-I want to seal my trunk off to force more bass into the cabin.

So for the box, is fiberglass a bad idea? Will fiberglass hold up to 4 SA 8s on 2000W rms daily? If I did do the fiberglass, it would make it much easier to seal off from my trunk because it would fit every contour of my trunk.. including the massive hump at the back of it. I could actually put the woofers above that hump facing towards the front seat.

Opinions? Ideas?

ahole-ic
01-10-2012, 10:18 PM
Are you suggesting a different car as well?

What happened to all the people on here that made things work in trunk cars? Buying a new car isnt something you just do for fun! lol -.-

Nope I wasn't suggesting a new car at all. There is a very specific reason the trunk itself kills your output.... because it is the outside chamber of your enclosure.

KTMrida4life
01-10-2012, 10:24 PM
Nope I wasn't suggesting a new car at all. There is a very specific reason the trunk itself kills your output.... because it is the outside chamber of your enclosure.

Sorry to assume that, Ive just been told that half a dozen times in multiple threads by probably the same person.

Isnt that why people seal off the trunk so they dont have that effect of a crappy 4th/6th order anymore? Is that possible here with the huge hump in my trunk?

KTMrida4life
01-10-2012, 10:28 PM
Could I build a box that had a big right angle in it if I kerfed it or something for better airflow? I want to build a box that utilizes that hump in my trunk with all 4 subs facing my rear seat, if thats what is loudest. If I built a normal MDF box, I could then fiberglass the outside corners to match the curves of the trunk to seal it off.. so the corners would look odd and not actually be part of the inside of the box, but they would fill the gap between the box + sides of the trunk so its airtight.

Is that possible?

ahole-ic
01-10-2012, 10:33 PM
Anything is possible but I think your BEST bet is to work with the bandpass effect. Do a clamshell design/6th order.

Kangaroux
01-10-2012, 10:35 PM
Build a box similar to what you have now but do like a 4th/6th order bandpass. Make the port external and removable, so the box goes in the trunk like normal, you load in the subs, and then attach the port while it's in the trunk (doing a detachable port not only lets you tune it but makes it easier to get stuff into a trunk cause you dont have extra ish sticking out of the box). Put your seats down and then fire into the cabin.

KTMrida4life
01-10-2012, 10:44 PM
Build a box similar to what you have now but do like a 4th/6th order bandpass. Make the port external and removable, so the box goes in the trunk like normal, you load in the subs, and then attach the port while it's in the trunk (doing a detachable port not only lets you tune it but makes it easier to get stuff into a trunk cause you dont have extra ish sticking out of the box). Put your seats down and then fire into the cabin.

Then I would have to keep my rear seat down all the time. Unless I bought a reat seat from another 240sx, and cut some massive holes through the seat for some huge aero ports. hahahaha thatd be sick

duanebro
01-10-2012, 10:50 PM
Could I build a box that had a big right angle in it if I kerfed it or something for better airflow? I want to build a box that utilizes that hump in my trunk with all 4 subs facing my rear seat, if thats what is loudest. If I built a normal MDF box, I could then fiberglass the outside corners to match the curves of the trunk to seal it off.. so the corners would look odd and not actually be part of the inside of the box, but they would fill the gap between the box + sides of the trunk so its airtight.

Is that possible?

Yes. It sounds like your tiny trunk is reducing your output. So take the trunk out of the equation by sealing it off. I wouldn't worry about the box being funny shaped, as long as it doesn't get to "skinny" somewhere. And if you use a piece of cardboard to cut out the shape of the trunk opening, then use that as a pattern. you should be able to get very close.