NEw BOX for the Q18

Fishy · Post by **Fishy** » Mon Mar 19, 2007 5:26 pm

Just realized something. Why do you need any bends? Your box is a lot more than 20" wide isn't it? Man we need a diagram, picture, or at least some dimensions, hehe.

Post by **GlassWolf** » Mon Mar 19, 2007 5:49 pm

Putting speaker cloth tightly stretched over a port is really no different than having speaker cloth grilles over the speaker itself, as almost all home audio, and a large portion of car audio speakers have already.

Fishy wrote:I'd be a little worried about putting grill cloth right over the port termination. I'd build me a grill cloth "box" that let the port breathe just a bit. If I understand acoustic transparent materials they're beneficial because they allow sound waves to propagate through them w/o reflections. Still, it'd seem to me anything covering a port termination would inhibit airflow, but if you allowed a little space and place it where the air velocity is not so high the effects should be lessened quite a bit. All the ported home loudspeakers I've seen leave some "breathing" room between the port and speaker cover.
Of course this is all conjecture. I've never tried it.
:P

subster87 · Post by **subster87** » Mon Mar 19, 2007 6:32 pm

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!!

Fishy · Post by **Fishy** » Mon Mar 19, 2007 6:58 pm

GlassWolf wrote:Putting speaker cloth tightly stretched over a port is really no different than having speaker cloth grilles over the speaker itself, as almost all home audio, and a large portion of car audio speakers have already.

All right. I wasn't sure about that. It just seems to me like grillcloth might effect port velocity a lot more than a pipe elbow would. I guess a 30 mph wind blowing back and forth through some grill cloth at 28 Hz ain't a big deal if the amplitude isn't much. I've just never seen any port with it stuck right over the end.

Thats interesting. I know there's a direct correlation between the cone velocity and linear displacement, X, of a driver at a given frequency. If you know one you know the other. The same should be true of a collumn of air vibrating in the mouth of a helmholtz resonator. If you know the maximum vent velocity you should be able to figure out how FAR that collumn of air moves back and forth too.

I don't know if we shouldn't be adding a bit of fluid dynamics to the equation, or maybe I'll just stick some grill cloth over the port in my truck and see if I can hear a difference.

:)

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:01 pm

pictures lots and lots they arent very good but they give you a much better idea of my plans hope this helps!!! o yeah no laughin at my plans haha.
http://s96.photobucket.com/albums/l171/ ... C00968.jpg
http://s96.photobucket.com/albums/l171/ ... C00961.jpg
http://s96.photobucket.com/albums/l171/ ... C00963.jpg
http://s96.photobucket.com/albums/l171/ ... C00964.jpg

Fishy · Post by **Fishy** » Mon Mar 19, 2007 7:04 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!!

I still think you're better off with a slot port. They're popular because they make port placement a lot easier. Did you look at the enclosure diagrams in that 13w3 pdf?

http://mobile.jlaudio.com/pdfs/11636.pdf

Simple stuff.

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:07 pm

look at my box then tell me anything is simple lol

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:15 pm

no i didnt add that in!!! wow good call it would add actually quite a bit... 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... And sealing the fiberglass to the mdf can be done pretty easily with a layer or two of resin and fiberglass on the bottom edges basically mold the box to the floor.
Im kinda getting excited to see this idea play out. I like the look of the trunk in person now... Carpeted with the amps moved should loook fairly clean. No wires any where just a s sub sticking up in the back of the trunk lol

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:18 pm

that would be alot of sand what i did was found the volume of a half cylinder which is was half the wheel well is, and then found the volume of the remaining cube. ANd the floor outside and in the wheel well is fairly flat my fiberglassing made it alot less flat that it was lol due to the cold wheather the damn stuff took forever to harden so it wiggled around before it hardened

subster87 · Post by **subster87** » Mon Mar 19, 2007 7:20 pm

well i now the cone is very close to 16inches i lightly screwed the sub down and its dark i dont want to go outside right now. and i can only guestamate dept of the dust cap shit maybe 2 inches...