ported clamshell help/build

[irpirate]

so i bought 16 12's today and want to put them in a ported clamshell. what neofrog did with his 16 10s is kind of what i want to do. iz sexy

something about lots of subs is just sexy to me. ive read through several builds, berniebp87s, colins, and neofrogs.

im relatively new to building, figuring out tuning for enclosures (and car audio in general for that matter lol) and have relied on torre's program to do the calculating for me. ive seen look at it like a normal ported box except itll tune lower, build and rebuild till you get it right, t-line quarter wave stuff and am just confused as hell right now.

also read neofrogs lets talk acoustics here he said:

I built it to have 1 ft³ per sub, and 5.9 in² of port per cube for control. The baffles are at 14° with a 7" separation in the back. Port is tuned to 34.7hZ.

This gives me close to 12 ft³ inside the clam as well for a reference. I figured matching the air space would play a role in the response of the horn.

which honestly confuses the shit out of me even more lol

ill gladly pay for someone to help me design a box if thats what it comes down to.

the subs are infinity reference 1262w's 300 rms each. mounting depth 6-3/8". max dimensions are 37.5 width, 48 depth, 33 height.

please help meeeee T_T ive really been wanting to do a build like this but dont have/cant find/have trouble understanding the knowledge.

thanks all <3

*edit i tried doing a sketchup but the programs kicking my ass

[Colin - STAPUFT]

That is definitely a good write up Intro. I can tell you have already done a good bit of research on your own. It is just when it comes to clamshell design, there isn't a whole lot of info out there and once you do find info, it can leave you

So 16 12"s !!! That is going to be a party!

Just curious- what vehicle are they going in, where will the front of the wall be, what power are you putting to them, how are you going to wire them... all that jazz.

NeoFrog's clam did give @1 cu ft per sub, but he is running 10"s I believe. I have 12"s and I have roughly 1.75 cu ft per sub. But- I do have a larger port or terminus than NeoFrog. It just seems to me that you might need more than 1 cube per sub.

Just know, the larger the enclosure and terminus- the more efficient the system (read- less power needed to get loud). That isn't to say it won't be loud if it is smaller. You could go on the small side and put more power to it.... Smaller boxes usually give the subs more reinforcement (read control) and makes it harder for mechanical failure (bottoming out) but puts subs at a higher risk of thermal failure if you power the hell out of them.

My real advice would be to build the box as large as possible- get every cubic inch. Once you have the bottom, top, & sides done- you can figure out where the back will be and then figure out the angles you want. You may want to go like NeoFrog did with one angle- or split it like I did with mine- I did it because space dictated it. I had to do that to get the volume that I needed. Once you have that much done, come back with the data and you can go from there.

Like you have seen a million times before- clamshells don't design like other boxes. It is a bit of wet finger in the air (unless you are Boon )

Keep us updated!

[irpirate]

thanks for replying! really appreciate any help i can with this topic. everything going into the worlds smallest suv...toyota 4runner lol. i rarely crank the volume but the subs are rated 300 rms each, all dual 4's wired down to .5. saz 3500 for power, maybe upgrade to the 4500 depending on how it does. i should be getting quite a bit of power out of the amp though. dc power 270 xp and 3 d3100's. id like to do more than one angle and squeeze a bit more space out of it, not sure if my skill level is quite there yet, but ill try my best to start. how far away do the subs need to be from each other? i cant wait to get started on this thing thanks again!

*edit - build will start this weekend! make the biggest box i can, hope i somewhat understand or can ballpark the tuning by then. also not sure if ill be able to find someone to help me with angled cuts.

[Colin - STAPUFT]

Speaking in generalities:

The closer the subs, the lower the tune (in part b/c they will "play" off of each other). Also the closer they are, the smaller the terminus will end up being- thus lowering the tune.

The closer you get them and the smaller the terminus, the greater the possibility of port noise.

Just wet finger in the air, I would try to have an area of at least 250 square inches of port... the more the better keeping tune in consideration- and go from there with the length of port/terminus. I know all things will vary depending on the cubic feet of box- but too small a terminus will tune too low and will raise the chances of port noise. Also, you really don't want to tune below the fs of the sub- especially with a box like a clamshell. That is one of the reasons a well designed clamshell needs a sub with a low fs. Those Infinity Subs have a really low FS of 25 hz and high sensitivity of 93. They look to be good subs that will work well in this type of box. It shouldn't be too much work to get them loud.

[fritosaregood]

Im getting more interested in clamshells now too. ill have to keep my eye on this one.

is the terminus your talking about the size of the port? or final exit of the clamshell?

[irpirate]

Those Infinity Subs have a really low FS of 25 hz and high sensitivity of 93. They look to be good subs that will work well in this type of box. It shouldn't be too much work to get them loud.

thats why i picked these subs low fs, high sensitivity. didnt want to go nuts on electrical upgrades. didnt know they worked well in clamshells though, added bonus

ill keep the terminus size in mind. im assuming you mean the opening closest to the back of the box (basically the port at the end). im gonna build the outside of the box either friday or saturday. see how big i can get it and then figure out angles for the subs from there. im gonna do the 3 rows of subs at different angles so i can get a bit more volume for the box. the box is probably gonna be a bit small for the subs so ill hafta figure the size of the terminus port thinger from there. ima need to run some numbers by you guys to figure out tuning though. to colin - what did you try to tune your port to? from what i remember you said you ignored the actual clam opening where it got wider and tuned higher than what you wanted to. then tapered opening acted like an extension of the port and dropped the tuning. i know this is very install dependent cuz my box will be narrower (damn 4runners) and the tapered part will be longer than what you did, but do you know what you tuned to and what the actual tuning ended up being? iirc you tuned to 35.

ive always though clamshells were sexy, most people probably do, but its definitely intimidating trying to figure it out with so little info on it compared to ported. ill keep you guys updated/take a lot of pictures and maybe put up a build log when im done. even though i already have all my electrical setup except for adding 1 more d3100.

[Colin - STAPUFT]

By terminus I mean the port- not the mouth of the box. I may be totally wrong on the terminology, so if I am, someone please correct me.

I thought I tuned mine to 35 hz but it ended up being way lower. The Terminus is what I calculated the tuning to- so we are talking about what you would call the "port" only in any ported type box. Where the subs mount- I didn't count. That, along with the angles and the subs playing off of each other ended up lowering the tune- not by much- but it is able to get get really low. Lower than a 35hz ported box does.

By yours being deeper- you can expect a lower tune. Sounds like yours will be narrower and deeper than my box. My box is pretty stubby- so if you have to go pretty deep to get all 16 12"s in there (like a tunnel) then expect the low lows. I am really anxious to see how it comes along and turns out.

[irpirate]

well as long as we/i know what you mean doesnt matter i think ima shoot for 33-34 tuning to start and see how that does, i luv me sum llooowwwsss. maybe ill try doing a swappable port.

youre anxious! im going crazy wanting to get started on this thing!!! haha if i had a garage here id be building this thing all night till it got done. ups man probably hates me. live on the third floor. had to drag up another d3100 and a head unit up to me today. 16 subs should be fun for him too. 4 63 pound packages lol.

[irpirate]

i get giddy just looking at it xD

[irpirate]

before i start building mdf or birch plywood? too many mixed opinions out there. id like to do birch, stronger and lighter but im not sure if what home depot and lowes carries is too porous or whatever its called

*edit - 92 vs 75 pounds per sheet. thought it be more of a difference for some reason. suppose it does add up using 2-2.5 sheets though.