View Full Version : help me get loud please.

03-01-2009, 09:01 PM
I have a 03 cavalier with a g34 yellow top and a single 3512 running at .7ohms on a very old school us amps 100hc running maybe a little over 1k watts. i built 2 boxes so far for this one 12" (was testing with a 12" bass mekanik before) one for street bass so it wasn't that loud on the TL. The SPL box (what I'm currently messing around with) is 2.5 cubic feet double walled (doubled up on mdf so 1.5" walls all around) tuned to 55. The sub is firing into the cabin on the passanger side and the vent which is 72^2 inches is on the drivers side of the box. I am following db drag rules so everythign is sealed up and mic on the windshield. I peaked at 43hz so that tells me the box is tuned too high. I reached a score of 141.0 I then took a piece of mdf the length and height of the box and put it in the vent. This brought the area to be 63^2 inches and the tuning was dropped to 50. I tested and came out with same results. I then upgraded my wiring from 4 gauge all around, to 0 gauge all around i gained .5db's. i have another plug that I will be throwing in the vent monday to drop the tunning to 44. i will then update you guys with the outcome and go from there. I plan on building another box but this time having the sub and the vent firing towards the cabin sealed off from the trunk. I just don't know if I should run a box at 2.5 cubic feet or smaller. i will be using a 6" precision port and start from 30 and cut away until I dont get any more increases. So my question for you guys is what would you recommend 2.5 cubic foot box or smaller?

03-01-2009, 09:05 PM
Small box, big port, and alot of power. Try a little smaller, around 1.75, tune it to the res. freq. of the car, and have around 1000-2000rms. Usually in a trunk two 12's on 2000rms ported gets in the high 140's, but depending on the install and how much money you have, it can be either or.

03-01-2009, 09:07 PM
your score isn't bad. tuning on the spl box is really hi and the box is too large. remember spl boxes are generally very small and tuned like 5-10Hz below car's optimal tuning in most cases. sealing off the trunk should help drastically. more power would help drastically too.

03-01-2009, 09:10 PM
there is no option of more power. there are some comps i go to that class you by power and i want to stay in my class.. so you guys recommend me going to 2 cubic feet with a 6" port?

03-01-2009, 09:14 PM
Then try smaller boxes with the new tuning and test it out. There's no definate answer as to if it's gonna be 3db's louder or not, there's so many variables that come into play when pressurizing high amounts of air, you just have to try it out and see what works best.

03-01-2009, 09:15 PM
I have done exactly what you are trying to accomplish.

I had a single 12" in the trunk in a SPL box tuned to 60Hz @ 2.5 cubes. Scored like a 146 with 2 Sundown 1500's strapped to it.

Sealed off the trunk, SPL-X firing into the cabin, made box smaller to 1.75 cubes and tryed again. This time I prevailed with a 151.3. Loudest I ever had it, just throw big power and seal off the trunk..


I miss that set-up.. :(

03-01-2009, 09:17 PM
what league are you in? It sounds like IASCA and if so they use the amp's 4ohm power rating so as long as the power rating at 4ohm is within your division's limits you are good. I ran a 1500wrms amp in the lowest division because at 4ohm it was only rated to do 500wrms

03-01-2009, 09:25 PM
do you guys recommend 2 4" or 1 6" ports?

03-01-2009, 09:26 PM
1 6" has more port area than 2 4"s so go with the single 6". even tho my box has 2 4"s and it gets plenty loud ;)

03-01-2009, 09:29 PM
the only issue with that is i will have to make the box longer to be able to use a long 6" vs having 2x shorter 4"

03-01-2009, 09:31 PM
yeah there's always sacrifices to be made when getting loud.

03-01-2009, 09:33 PM
2 4" PSP Ports would work plenty well. Thats what I used..

03-01-2009, 09:35 PM
is there any difference between 6" port and 4x 3" ports? same area just smaller ports but with more.. would there be a bad side to this?

03-01-2009, 09:39 PM
if you can find a way to get them all on the same plane I don't see a problem with it.

03-01-2009, 10:04 PM
I tune my box in the vehicle. I seal all sides but the back and the port wall ( I like slot ports ) and test and cut till I peak out. Hope that helps.

03-01-2009, 10:19 PM
ok im gonna take thors advice. im gonna build me a box to 2.5 and seal everything but the back panel. i will be using 2x 4" ports and i will be using pvc piping as test runs. first test will be 2.5cubic feet tuned to 35. i will then cut the pvc with the port flares on them until i get loudest. then i will decrease box size by screwing pieces of mdf onto the back wall and putting it inside the box. i will then keep testing like this until i get the loudest combo and then cut the box to that and then use the real port tubing (to keep the nice black look). I should be all good after this. now the question is, should i keep tuning with the box i have now? or should i move onto the next box and scrap this one?

03-01-2009, 10:21 PM
remember, just putting mdf inside the enclosure might effect air flow. if the airflow is slowed, sound waves won't move as fast. slower waves may mean less spl.

03-01-2009, 10:47 PM
no i will be doing it to the inside dimensions so that in the box it will be seamless pretty much just like moving the back wall inwards by adding thickness towards the inside of the box. pretty much cutting a board to the inside dimensions of the back wall and putting it in the box against the back wall. get what im saying?

04-15-2009, 09:12 PM
ok so i had a spare box around that i have been testing with.. the box is 15"tall x 15" deep x 30" wide. i put the sub and ports on same side. the ports are measured at 11" from tip of flare to toe of flare.. net box volume after displacement is about 2.7 cubic feet. i peak at 41 with the box firing back and reach same score of 141. :( im gonna start cutting the ports to see if any gains are available.. i will then start shrinking the box by cutting the back wall but i will also have to build neck like spacers for teh ports so that i can still have enough distance between end of port and back wall (from wall to wall is 15" right now.

05-10-2009, 05:59 PM
first competition of the year and with my 100hc i hit 141.2 and with a Hifonics BXI2608D, i hit a 143.6 :/ lost to a guy with a rf 1000watt (dont know class) and a dc sub with an atomic motor which hit a 143.9. :/ i might go back to vents cause i dont think 2x 4" ports are cuttin it for this sub.

05-10-2009, 09:42 PM
There's a guy in MECA doing 150's at the headrest out of a Cavalier trunk. He has two Crossfire 10's and about 6kW.

05-10-2009, 09:46 PM

05-10-2009, 10:00 PM
Nope, I personally know him.

05-10-2009, 10:03 PM
i know who ur talking about......

u gotta learn your car. that's the only way to loud Deebeez

05-11-2009, 10:26 AM
how do i go about doing that?

05-11-2009, 03:25 PM
Everyone said to try a smaller box, but you went from 2.5 to 2.7?

05-11-2009, 07:26 PM
no i went back down to 2.5 haha i got a different box. im gonna cut it down a little bit pretty soon to 2.25

06-25-2009, 01:22 PM
ok so i cut my current box to 2.0 cubic feet outside demensions are the following. 30 inches wide X 15 inches tall X 11 inches deep. I have 2x 4" ports at 17" long tuned to around 40. Do you think having the sub that close to the wall is a killer? from wall to wall inside is 9.5 inches. i also have the sub and vents firing sideways instead of forward as the vents are quite long.

06-29-2009, 01:24 PM
ok i got a 144.3 at 43hz.. any more ideas?