View Full Version : Port(s) Loading off of trunk lid? Subs/Port up in trunk? Volume/Port area as well?

04-04-2013, 06:31 PM
Sorry guys, my original post was too long, so I just got frustrated after having to submit it like seven times and it still being too long. So if it is all choppy and all over the place please let me know and I can explain or reiterate more clearly. I just started chopping parts off randomly and whatnot so... Yeah :-/


going to be two 15" Mach 5 SPL-15 drivers, but with Warden recones that I had Nick at IA make for me, to where the spider pack was made to be quite near in stiffness of the stock Mach 5 softparts/recones. Just that instead of having a seven spider pack, there are less spiders used that are much stiffer LOL. Three stiffer spiders were used to obtain nearly the same stiffness. I just wonder if the TSPs of these newly built drivers will be somewhat near of those of the stock SPL-15s, with softparts that are very near in stiffness of the spider pack, what looks to be the same foam surround in terms of thickness and size/roll amount though the IA one is probably much better quality, the only differences that are big is the fact that the cone is A LOT lighter than before, and that the coil is a decent amount lighter than before too. IDK what that difference in the softparts would do to the TSPs. Any ideas? Aside from mms going way down LOL. If the TSPs were near the same, then I'd know EXACTLY what I'd do for enclosure specs because I don't think anyone out there has as much experience with the Mach 5 SPL-12s and SPL-15s as myelf except Mark and Murilo probably :p
It'd be great it I had a Woofer Tester software *D'oh* If the TSPs were somewhat close to stock, then I'd be golden and go build right away.


to begin with, Most people have stated to start with, and Nick included, 4 cubes per driver net, with 50sqin of port and tune to liking. 8 cubes net, and 100 sqin of port seems like WAY more than needed IMO and experience, especially if I can easily go kerfed or aeroports. And IME aeroports and lesser port area has always been louder for me, just like Anton has been doing well with, and Hack preaches. Lesser port area as long as it is efficient and useable port area is "louder." For daily I'll probably be giving them closer to 5kW daily to the pair, if the extra power isn't "necessary," in your opinions. The thing is, the stock Mach 5 SPL-12s did AMAZING in just 1.6 cubes net each at 33Hz with an awesome musical passband. The SPL-15s did amazing in 2.5-3 cubes as well. Now that I have different softparts in there, but nearly the same stiffness just A LOT lighter cone, and bit lighter coil how much difference that'd make.


I'm wondering if anyone has had good luck with woofers and port(s) firing upward inside a trunk before? What about say subs at an angle towards the rear and the lid, or opposite towards the cabin/rear seat and deck? If I had enough depth, I would try to do a side firing enclosure. Where the subs and ports would be firing toward the driver's side, all on the same baffle. But I don't have just the ~30" of depth for mounting the woofers and not even the port LOL. Maybe subs both firing into the driver's side and port rear or something. Or hell, even keeping enclosure centered in the trunk, keeping her thin enough to where 3" to 5" would be on either side of the enclosure, keep it tall and deep, having the subs fire into each opposite side of the trunk, with ports back or side firing on the same baffle the woofers would be on? LOL, quite ridiculous with all these ideas I'm getting at, though usually simple is best.

Unfortunately my rear seats DO NOT fold, nor do they even have a ski hole, nor are they even perforated. Nope, solid freakin' 1/8" steel formed behind the seats, and only the deck is somewhat well perforated. I might use a hole saw and perforate the rear seat with lots of holes in 3" or 4" diameter with a metal hole saw of mine. Good idea?


I had the best luck with my 12" woofers up onto the deck and port to driver's side. Unfortunately, I don't think I could keep enough volume if I kept the same orientation, perhaps it'd be 2.4-2.7cubes net per woofer if keeping that orientation. On the port side of the enclosure, there would be maybe 3" to 4" of width between the port side of the enclosure and side walls of the trunk and it'd taper down more as you go forward because of the shock towers would squeeze down the width. There would be some 17" down to 14" in height in that area as well, on that port side for it to head towards and into the cabin. But, not much room would be above the enclosure between it and the lid/deck to allow much into the cabin via the deck. I just wonder if the few inches of width and the height for the port rebound to head towards the cabin would essentially choke it off, or if that is enough room in your opinions?

The woofers would then be very close up to the rear deck in this case.
How far would you keep the woofers below from the rear deck while sitting static? Of course I'd make sure to keep the estimated amount of excursion in mind.


I figured that the more room or volume between the enclosure top/baffle and deck and trunk lid for the front wave and rear wave from the woofers/port(s) to have to enter the cabin without obstructions would be quite beneficial? This leads me to my next idea I was thinking using a decent amount of room between the top of the enclosure and "ceiling" of the trunk lid and rear deck if going both upfiring. Removing the floor, to obtain some more height volume, but keeping a decent amount of room between them.

I was thinking essentially the two drivers firing up onto the rear deck, mounted in each forward corners of the enclosure just a tad away from the vertical walls of the enclosure "corner loaded," woofers essentially. Unless that corner loading concept serves no value to have them mounted in the like that?

And I'd have the port or ports upfiring onto the trunk lid as far back as possible. Right where the horizontal and vertical portion of the lid meet, like where the bend is. Luckily in this car, there is a lovely large gradual radius of a curve forward instead of like a 90 degree bend between the vert/horizontal portions of the lid; in theory I would HOPE that would help direct the rear wave or port wave/rebound forward towards the cabin. And with that extra room between the enclosure top and lid it'd be easier for it to head up towards the cabin. But, will the woofers firing upwards as well, cause cancellation because the rear wave out of the ports as it heads forward above the enclosure will meet with the front waves coming off of the woofers?
On the notion of cancellation moreover... Unfortunately the subs will also fire onto the trunk lid a tad since the rear deck is not 15" in depth/length so most of the sD will be firing onto the deck and maybe anywhere 20%-35% of the sD will be "behind" the deck and will be firing onto the trunk lid as well.
I'm worried about what would happen if I had both firing up like that? Would the same concept that happens sometimes inside SUVs with both upfiring happen? Where the roof/ceiling may become nearly perfectly out of phase 180 degrees and cause for immense cancellation? I know people recommend never loading directly off of the trunk lid, but the lovely curve forward on the lid is so enticing. And, I would have NO problem peeling the deadener off of there, then fiberglassing a couple layers and whatnot to beef the hell out of that curve and go some forward on the lid and down the vertical portion of the lid some so what the port(s) would load off of and more would be solid, then perhaps I'd toss a layer or two of deadener over top of the glass if it'd make any difference. I was thinking of taking all of the shrouds and carpet and floor stuff et cetera out of the trunk to open up any space available, it's a newer Mercedes so there's LOTS of them, and I'm sure I could gain a bit, or at least allow smoother surfaces to allow better flow into the cabin. I'll heavily deaden the trunk even more than it is already too.


If going this route, would you corner load the woofers up front on the baffle, or in any of these orientations where more than likely I will have to go with woofers up anyway, WHERE WOULD YOU PLACE THE WOOFERS ON THE BAFFLE? IS CORNER LOADING NOT BENEFICIAL?
Then for the port(s), say if doing two 6" aeroports, would you do each port in each side of the rear panel and centered in height of the rear panel? Or each side, but then on the bottom of the rear panel? Or if it better to keep the ports together in either one of the side of the rear panel? I've seen SUV enclosures with using aeroports on either sides of rear panels, and I've also seen them bunched together on one side or another. I've always thought that having ONE PORT or if having to use multiple ports that you want to have them as close together to act as one port essentially. Even though that won't do anything for decreasing air/port friction per se.


If I have the possibility of giving each woofer about 3 cubes net, possibly more if I can obtain some decent amount with the removal of all the shrouds and floor and carpeting.... What would you do for a port or ports? I would have no problem doing two 6" aeroports, doing one 8" aeroport, two 8" aeroports, or even doing a single sided kerfed port the entire width of the enclosure and 3/4" roundover on the other three sides. Or, if you'd recommend instead of going the entire width, I could go with a more square shaped port with single sided kerf probably utilizing 2.5" radius kerf either way if you'd recommend going that way instead of aeroports. What would you do for port area if doing a kerfed port? And of course I'd stay below the... err 7:1 ratio of width to height deal. IIRC it was 7:1 that most people recommend staying below.

04-04-2013, 06:32 PM

At the moment, I have essentially ~35"Wx15.5"Hx24"D (6.1 cubes internal gross). I could add some 1/2" here and there, and probably 3/4" in depth but possibly almost 2" in depth if need be. But possible I'd rather go like 34.5"Wx14.5"Hx24"D (5.6 cubes internal gross), quite small, but lots of power is had, so IDK. The stock SPL-15s would have been just fine in that, but who knows on these newer softparts LOL. Another way for dimensions, it'd be 6.3 gross internal, and I could get 2.87 net per woofer at 33Hz with using two 6" aeroports for the enclosure. IDK.

Thank you guys. And I sure hope some enclosure gurus can chime in too!

Thank you guys SO freakin' much,