NEw BOX for the Q18

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:21 pm

o yeah and dumb question but how do i be sure the surround isnt hitting the box??? when its upside down....

Fishy · Post by **Fishy** » Mon Mar 19, 2007 7:22 pm

subster87 wrote:i really dont think you can handle the dimensions lol its REDICULOUS!! lol so ill find the damn camera i have the box in well most of it anyway. i have gaps to fill pain in my balls, and i still havent found a spot for a port. How many six inch PVC ports would i need?? lol im sorry but i just am stumped on the port placement right now i have till saturday morning to finish this damn thing thats when i take it to be carpeted like three hours away!!

Ahhhhhh.... from your pics I see your problem now, hehe. So if I understand correctly you've glassed in the floor of your trunk and are working on sealing it up with the bottom of the box. Yep, if you don't have a flat bottom surface maybe some 6" in pvc ports would be simpler. Lemme cruch some numbers in WinISD. God I wish my new calculator would get here. Make subtracting port displacements a helluva lot easier.

:P

Oh yeah. Do you have more clearance on the sides than by the amps? and did you figure in the "negative" speaker displacement with the sub inverted? Looks like there might be a good bit of volume contained in that cone. It should add some airspace to the enclosure.

If you haven't try "sand(clean) and a measuring cup". Water would NOT be a good idea. Maybe sand ain't so good either. Just guess, hehe, or give me the depth and diameters(top and at the dust cover) and I'll find an equation for the volume of a cone.

Fishy · Post by **Fishy** » Mon Mar 19, 2007 7:31 pm

Yeah I realized the limitations of "sand" and edited things. It seems to have moved my post down a bit. Just measure the depth from from top of the cone(level with the top of the surround) to the dust cover, the diameter of the cone at the surround and then the diameter of the dust cover. With that and the enclosure thickness and cutout diameter we can get a crude idea what we'll be adding.

God. Anyone remember when you just built a box with about the right amount of space, stuck a cardboard tube in it, and cut it off till it sounded good? Things used to be SO much simpler, hehe.

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:34 pm

lol ok so ill measure that all in the daytime tomorrow
yeah i used to use the nieve technique and guestimate all my measurements

Fishy · Post by **Fishy** » Mon Mar 19, 2007 7:45 pm

subster87 wrote:And yea i wish i had more room to get my camera in the trunk lol. and explain what you mean by more clearance??? those amps are moving i just havent had the time to build the racks on either side of the sub yet...

It would be easiest to place the ports on one of the 4 sides of the box, with the back(by tailights) being optimal, but you have to have room for them to breathe or part of your trunk becomes part of the port(that stupid end correction stuff) which can lower tuning. Where will you have the most space for the ports to fire horizontally? Front(by rear seat), rear, or one of the sides?

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:48 pm

one of the sides by the tire wells i have 5 inches and toward the ineterior of car i ahve basically unlimited but i was told not to fire toward the rear seat. and toward the trunk i have like two inches. and horizontally i have like 12 inches clearance...

Fishy · Post by **Fishy** » Mon Mar 19, 2007 7:56 pm

subster87 wrote:lol ok so ill measure that all in the daytime tomorrow
yeah i used to use the nieve technique and guestimate all my measurements

Lol, GOOD. My HP calculator should be here in a couple days. This 4 dollar POS suxxorz for figuring this stuff out. I'm just gonna use .16 ft^3 which is 2/3 of the speaker displacement Fi quotes in its specs. I think we're splitting hairs here anyways.

In the meantime I can at least tell you how many 6" ports you need and about how long they have to be.

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:57 pm

that would be great

Fishy · Post by **Fishy** » Mon Mar 19, 2007 8:05 pm

subster87 wrote:one of the sides by the tire wells i have 5 inches and toward the ineterior of car i ahve basically unlimited but i was told not to fire toward the rear seat. and toward the trunk i have like two inches. and horizontally i have like 12 inches clearance...

Yeah you may get some weird cancellation issues firing into the cabin, but I think the most important thing is to get the tuning right. Its been two years since I looked into this cancellation stuff:

http://www.teamrocs.com/technical/pages/aiming.htm

IIRC the cancellation issues aren't such a big deal with the lower frequencies your port will be playing at. Firing forward sucks mainly for the driver itself. I gotta go over that article again to make sure though.

subster87 · Post by **subster87** » Mon Mar 19, 2007 8:15 pm

i know firing in the opposite direction of the sub has cancelation or so my local dealer instills on me. I know firing the sub into the cabin without the trunk sealed cancels but i dont know about if its just the port with the sub firing up. I think my best air space would be firing up simplest to get onto the box also. THe demensions within the box are freakin nuts they get complicated quick