18inch BL new box

[worrblade 0]

i am making an spl box and going to get into a few small comps this summer.

i am going to tune the box to what ever my car is tuned to (not sure right now)

the bigger the box will i get a higher number?

i will probably end up making it a removable port so ill have something for street beat and for spl.

SPL IS THE MOST IMPORTANT! so how many cuft?

its an 18 BL fully loaded powered by a rockford power 1000.1 in a VW golf

[johnecon2001 82]

How much room do you have?

[worrblade 0]

How much room do you have?

i can probably fit 20 cub feet. but for the port to really breath it would have to face the front of the car. i took the back seats out. the box i have for it now is 8ft3. i can get more than 20 but it will have to be something other than a box shape. size is really not much of a problem. i know its a small car but one of the main reasons i got it was for an overly big system.

[BKOLFO4 29]

Use the box you have now to determine where your peak is in your car. You can change the port tuning and test (repeat over and over) and see what works out best.

For SPL only, the box size and tuning work together to make the most SPL - the biggest box you can fit is not always the best solution.

Testing, testing, and more testing.

Brian

[worrblade 0]

Use the box you have now to determine where your peak is in your car. You can change the port tuning and test (repeat over and over) and see what works out best.

For SPL only, the box size and tuning work together to make the most SPL - the biggest box you can fit is not always the best solution.

Testing, testing, and more testing.

Brian

i was told that i needed to have a sealed box to find what my car is tuned at. the one i have now is ported to 37 Hz.

i didn't think that bigger would always be bigger... but how can i find out what will work best for the size? do i just make a few boxes that are different sizes and tuned to the same fq?

[BKOLFO4 29]

I have never built a 100% all out SPL only setup - Even when I wanted it to get loud, I still wanted to be able to play music.

For my original dual 18" setup, I was space limited, so I went with the largest box I could and then tested port tuning frequencies from 30 to 63 Hz by pretty much cutting 1/2" at a time off of my port (yes the box got slightly larger each time.)

Took readings - measured SPL, the actual impedance, true tuning frequency, and power output from the amplifier from 30 to 65 Hz for each port length.

I then graphed all the data (tuning, box size, power, and output) and determined the length I wanted the port to be.

My latest setup is just 12 ft^3 tuned to 35 Hz with 200 inches of port area. Wanted something that would get loud and do an awesome job of playing music.

You can download something as simple as the spreadsheet on DIYSubwoofers.org and play around with frequency response of different boxes at different tuning frequencies. I use that spreadsheet a lot for designing boxes. . .

Brian

[worrblade 0]

that is a good idea.

i was told if i had a sealed box i could use a test CD that went from like 1 to 100 Hz really slow and see which one is loudest. i have a mic i can use.. ill look on that site!

[NDMstang65 403]

Honestly the only way you are going to get loud is hundreds of hours of testing...the sealed box thing really does not work, because once you get the bigger enclosure in there all of the acoustical properties has changed...

Only thing i can really tell you to do is build as big as you can, you can always make the enclosure smaller, but making it bigger becomes a problem...tune high with a substantial amount of vent area, start testing and choke vent area or tune lower and cut down on box volume until you peak...

Thanks!

-Nick

[BKOLFO4 29]

If he has 20 ft^3, would you start that big for a single 18? I am just curious. . . .

[worrblade 0]

i was thinking about starting with 12... not really any reason y.. just sounds like a good size to start with. one 18 with 20 cube seems to big.. but i could be wrong.

i was going to do the sealed box thing with the box size i wanted already setting in the car.

i just don't know how to test the size.. i am in class ill post again when i get home what i am thinking. u guys are helping!

[worrblade 0]

i was going to make the box but not put the port on it or the sub yet and then put it in my car and use the sealed box to see what its tuned to.

so what u guys are saying is that i will have to make a box as big as i can and cut it down slowly and see how many db i get?

if i do that i will what the box is tuned to will change unless i cut the port every time. but i guess i could do that. after i find the best size then i can see what the best tuning is.

do u guys have any idea or even close what might be something close to the best size?