I had a single 10" subwoofer and now going to go to two 12" for better SQ at lower listening levels. Room has been a problem and 12" drivers need air space, so I made a "mock up" of the box I will be building today that may work well. I'm going with a set of I-12 SVC Zapco subwoofers. I'll post my progrees if you all are interested, AL.
Years ago, I got a 15" subwoofer from Crutchfield. They gave a formula in their catalog that helped you determine how much volume (i.e. space, not loudness) you should have in the subwoofer box for optimum sounds. I built a box to their dimensions, and although it was a bit bigger than I would like, it does sound absolutely fantastic. I just did a search on the crutchfield website but I could not find their formula any more. -Bob C.
The new Zapco subwoofers was a challange because of the large basket and magnet structures but will be worth it when finished, AL.
Those are meaty. Keep the posts coming:beer I've got a pair of 10" Kicker comps in the Centurion, and they make my ears bleed if I get too itchy with the volume button.:laugh:
I installed a new Zapco AG-650 amp and now I have enough power to run a set of 12 Zapco subs, here is a picture of the the new amp but soon to have a two 12s instead one 10, AL.
I did do that on another post and I still got the same error message. I PM-ed David on this and I'll let you know whats up, AL.
Adam, I posted the picture a wile back of the amp...... http://www.v8buick.com/showthread.php?t=116217&highlight=zapco AL.
Al, what kind of power will those handle? Back in the day when I had a thumpin' stereo I ran two 15" Alpine compitition series subs mounted in a bandpass type enclosure. That thing was huge, filled up the entire back of a fullsize Jimmy (behind the rear seat) I was running 400 watts into each sub. If I cranked it up the wipers would bounce off the windshield. I had 1120 watts total and could hit 132 db.
Al, The box looks small for volume? Remember, you need to account for the driver it's self as part of the equation, the driver takes up a lot of space. Also, the box has to be sonicly dead. For sub woofers I use 1.5" MDF. I don't know the specs of the sub your using, usally 1 - 1.5 cu' box is required, for auto subs. For two 12" you might want to consider an IB (Infinate Baffel) design, this uses the trunk space as the box, you just need to make sure the back wave, of the speaker, never makes it to the front wave. Here's a good website for reference: http://www.geocities.com/the_technoweenie/ You need to be concerned with the "Q" of the box. Too high and it will sound muddy, too low and won't give you the thump your looking for. Look for the Qtc tips, down on the page. Hope this helps, Rock On:TU: Rich
I agree... That box looks way too small for those woofers. Small box can lead to compressing the cone and blowing them right out. I personally don't like "Free air" woofers (using the trunk as a box).. as those tend to perform under par. If you "HAVE" to run that box to fit em in the well.. I'd make sure you vent it, It'll hurt your SPL's but if you vent it right, could be good for SQ. Passive Radiators also help with "Compression". Lookin nice.
Rich, I think your right and if I put a divider between the two would make it worse! Space in the rear of the car is the problem. I guess a vent or porting may be an option, AL.
The mesurements are 10" Deep X 30" Wide X 7" tall. Not real sure how the do the math my cabnet iside space, AL.
You may want to try turning the subs so that the cone faces into the box (inverting). It will give back the added space from the subwoofer basket. If you do this, change the polarity of the wires too. If you port the box, more than likely, you will acheive the effect of less air space. Nearly every sub manual suggests a bigger volume once you add ports. Stuffing the box with pillow polyfill or fiberglass insulation will help "trick" the sub into thinking its in a bigger box. Do a lil online reseach at you may find a few more options.
Nice Build, are you putting this into your Century? If you need to find the volume of the box, you have to do a couple calculations and measurements. The box has properties of a rectangle and a prism. I don't know if it would be considered a trapezoid, because I dont' remember the definition of a trapezoid. If I remember, volume for prisms = Area of the base times height. Since your box is laying down the base will be the triangular section and the height will be the length. You need to measure just the prism (triangular) section of the box and calculate the volume of it seperately from the rectangle. (the formula for area of a triangle is A=base times height times 1/2) So take the area of the triangular base and multiply that by the box length. Then you have the volume of the slanted prism portion. Then once you have found the prism volume, add that to the volume of the rectangle, which is just length times width, times height. Then subtract the woofer basket volume, which is a very complex measurement, so hopefully they give it to you in the manual. You could get a rough measurement of the basket by using the forumle for a truncated cone frustum -Mike
Show us some more pics. I always loved building systems. The box is small, but I remember you noted earlier that you were going for good sound at low volume levels, so you will not be pounding them hard. Infinate baffle design (mounting them in the rear package tray without a box) would work good at low volume levels. These customers would only play the subs at half volume, but they still hit deep. The small box you have will be good for hard rock and will hit quick. Just don't overpower them. Ports and polyfill will help make up a difference for small boxes. Inverting subs like mentioned above will help too, but it will take up the space that it sounds like you need in the trunk.
I'm just spitalling here- but your running a box under 2 cubic ft. Subtract your speakers- thats a big speaker- but you only have to account for the magnet and the cone- so I'd say your probably losing .25 cubes per speaker. Now you are under (way under) a cubic ft per box. And I would recommend seperating them with a divider- for strength. Polyfill will give you about 10%. Your still under a cube per speaker. Remember though, you can pick up airspace without ruining your box. Speakers only know air volume. they don't care where it comes from. As long as your system is sealed (if you are running a sealed enclosure) you can add airspace (remotely) as long as its sealed. Say you do the math, and you still need to come up with another cubic ft per speaker. You can build a sealed enclosure located somewhere else and tie them in together. Its harder to explain than it is to build, but it works. You can invert your subs, and you'll pick up almost double the vas (airspace the sub occupies)- send a snapshot of the speaker specs & manufacturers recommendations, and maybe I can help you out more. Bryan
Al 2 10" DVC's maybe would have been a better choice 12's are a good all around sub trust me one single 12" DVC with enough power hits really hard!!
