pervitizm

The box is for a pair of DC Level 4 18's in the back of a 2007 Suburban with all seats in, including the third row.I have the following for outer dimensions to work with: 27 x 49 x27 Now my drawing shows a height of 26 1/2, but I'm only counting the height at 25 3/4 in the Box Calc program because the top board was double baffled. I'm seeing a box tuning at 33hz. Here is my other design, this one is pretty much the same as the first except for both subs and port firing up. What do you guys think? Box Design: I think I still like the whole port and subs up design better. My current box is a dual chambered double slot ported box. Each chambered tunned to 32hz. Has anyone gone from running subs up/port back to subs up/port up and if so did you like the outcome of that change? I've always ran subs up/port back and don't want to go through the hasle of changing to subs&port up if my output will suffer.

Subs are about 11 months old although I've only had them playing for about 7 of those months. So the subs are seasoned sort of speak. I've notice this sound since I've had them but I always thought that it was the Autotek amp that I had on them. When I changed that out for the pair of kicker I have on them now and it was still doing the same thing that lead me to believe that the sub itself might be messed up.

I've posted this under Subwoofer/Enclosures section over on SMD but I figured I'd post it here as well since this is another DC sub forum. Any thoughts on what this could be? name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src=" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="295"></embed></object> "> name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src=" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="295"></embed></object>" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350">

Thanks for your help. I was confussed with the photo from the instructions. Cause it looks like I can go from the alt to the relay instead of the primary battery to the relay.

Its a Pacific Accessory Corporations PAC-200 Mobile Audio Relay and battery Isolator http://www.pac-audio.com/instructions/PAC-200.pdf This relay isolator is designed to prevent voltage drop on the second battery.

I just got it in the mail today and I want to intall in my 07 Suburban. Anyone here who has this install on they're tahoe/suburban, where did you mout these unit at? Did you mout it on the firewall, or did you mout it near the fuse box? Is there an easy accessory wire available under the hood that I could use to turn the isolator on/off? Also is there anything else I have to do special with this isolator since this is a newer truck? From the directions it looks like I'll go from the alterntor to the one of the isolator's hot lead. Then from the 2nd isolator hot lead to a fuse/relay switch, which will then go to the second battery. Does that sound about right? Then there are two smaller leads on the isolator, one for ground and the other for the accessory wire to know when to turn the relay on/off. Yeah I'm confussed just typing this, so if anyone out there can lend a helping hand....or reply I would be forever in your debt.

After seeking help from numerious forums..(ROE, Termpro, SSA, and SMD) I've narrowed down my box design to just two for my DC LvL4 18. I just do know which one I want to build. Should I go with box 1 or box 2 Box 1: Tuning is now looking right at around 33Hz. Box 2: Tunning is around 30Hz

I think I pretty much laid out my goals, which is box for pair of Lvl 4 18's tuned around 32hz with both subs and port firing upwards. I guess after reading my post above I really didn't clearly stated what I was looking for out of this post. What I wanted to know was did I do the tuning formula correctly? If I have that fomula correct then I can redesign the box to meet my tuning tuning needs. Daily driver that tuned for music mostly hip hop, rap and r&b. However I listen to a lot of different types of music so I want it to still sound okay if I play some old Duran Duran or Korn. It just that 90% of the music I listen to is hip hop, rap and r&b. The T/S parameters can be found by going here. According to the T/S the subs need around 5.75ft^3 of space per woofer. So I wanted my box to fall right around that with bracing accounted for. so I figure if I can get around 11.5 to 12ft^3 of internal air space then I should be straight. Yeah, it appears that most of the folks I've talked to on all the other forms have suggested that I go for the more traditional CRX style of enclousre. So I haven't rule that out totally. I'm in the process of redesigning again just to see what I can come up with. Doing this is a lot cheaper than buying MDF and getting the box all wrong.

I recently brought a pair of LvL 4 with LvL 5 coils to go with my single Autotek MM4000.1D amp. I want to put these subs in an 07 Chevy Suburban LT.The idea is to keep my third row seats. That was the main reason why I brought a suburban instead of a tahoe. So far this is what I've came up with. *Note all measurements are external* Height: 23 3/8 inches or 28 1/2 inches if I go up to top of headrest Width: 49 inches Depth: 28 3/4 inches I went to 12volt.com to use their volume calculator and it came out to roughly 15 cft of internal volume space. I want to go ported with the 18's and I want to go both subs and ports facing up as apposed to subs up and ports to the rear. So I created a couple different boxes using Sketchup and I used this box volume/port area thread on ROE to help me out with trying to figure out the tunning and port area. The first box I did was a single port in the center of the box between the two subs firing up. Box external measusrments are 24hx49wx26d. Both the top and bottom are double boarded. The port opening is 5wx24.5hx10d. The second box I made was one where it had two ports. One on each side of the subs. Again both the top and bottom were double boarded and the ports were 2.5wx24.5hx10d The third & forth boxs are ones I did based off of some help I got over on SMD. I also need to note that I've only used the tuning formula and other tips from here on box 3 and 4. This box has an 8wx24.5hx13d port, which is a single port off to the side of the box. While this box is more of a CRX style has a port 8wx21hx13d. Now here is what I came up with as far as tuning when I plugged in the numbers for both box 3 and 4. External 24Hx49Wx26D =17.7 f^3 Interneral (Before Displacement) = 14.14 f^3 21Hx47.5Wx24.5D Port Opening is 8 iches Wide and the depth is 13 inches Box 3 is 8Wx13Dx24.5H- port area is (8x24.5 = 196sqin) Displacement: (8.75x13x24.5)/1728 Box 4 is 8Wx13Dx21H - port area is (8x21=168sqin) Displacement8.75x13x21)/1728 Fb = 0.159*SQRT[(Av*(1.84*10^8)/(Vb*1728*[Lv+(.823*SQRT(Av))])] LV is the length of the port AV is your port area VB is your boxes internal volume(every displacement accounted for) Fb will be your tuning frequency once you work the formula through. Box 3 Fb = 0.159*SQRT[(196*(1.84*10^8)]/(14.14*1728*[13+(.823*SQRT(196))]) SQRT (196) = 14 10^8 =100000000 Box 3 Fb = 0.159*SQRT[(196*(1.84*100000000)]/(14.14*1728*[13+(.823*14)]) 0.823*14 = 11.522+13 =24.522 14.14*1728 =24433.92*24.522=599168.58624 Fb = 0.159*SQRT[(196*(1.84*100000000)]/599168.58624 1.84*100000000=184000000 184000000*196=36064000000 Fb = 0.159*SQRT[36064000000]/599168.58624 36064000000/599168.58624 = 60190.08 Fb = 0.159*SQRT(60190.08) SQRT(60190.08) = 245.336667 Fb = 0.159*245.336667 Fb = 39.008hz Box 4 Fb = 0.159*SQRT[(168*(1.84*10^8)]/(14.14*1728*[13+(.823*SQRT(168))]) SQRT(168) =12.9614814 Fb = 0.159*SQRT[(168*100000000)/(14.14*1728*[13+(0.823*12.9614814)])] Fb = 0.159*SQRT(16800000000)/261442.944 Fb=0.159*SQRT(64258.8) Fb= 0.159*253.493195 Fb = 40.305hz Sorry for such an loooonnnng post, but I want to make sure I have the whole port area and tuning formula down correctly. If this is so then I'll know what to do to make port adjustments. As you can see both box 3 and 4 if the numbers are right are tuned really high. I was shooting for more of a 32hz - 35hz range.

Great build so far. How big is your box?

Ok here we go. This is my third redention of this box. This time I did dual ports on the side of the box. I had to adjust the depth just a bit from 24 to 25.5 inches. Let me know what you guys think. I've got Monday off and I want to get my build on So my new numbers are 24H x 49W x 25.5D. Top and bottom are double 3/4 MDF while the front, back and sides are single 3/4 MDF. The ports are 2.5W x24D x 10H.

Okay so I have to admit this was my first time using Google's SketchUp software and I'm hooked. By far way easy to do a drawing with rather than AutoCad. Anyway this is what I've come up with using the measurement that Wagonized gave me. I made an adjustment with the port though. I brought the port up to the top, extended it's width by 4 inches to 24inches and decreased the height to 10 inches. Let me know what you think?

How about this, using the design above I want to have the port firing from the top. I want the port to be the lenght(width) of the box. How would I re-calculate that so that the tuning would stay right around that 30 -35hz range? In other words when it comes to the measurement of the port it would be around this: width:46 x depth:5 x height?? I guess the key measurements for this is width because I want to try and keep the port opening as wide as the box, if that makes any sense.

Thank you for the idea. This will at least give me a starting point as to where I need to go. The reason why I wanted to go sub/port up was because I don't think I have enought space between the vent an my rear hatch door. At most if I were to use that box design I would have about 4 inches. I was told that I should have at least 6 -10 inches of space between the vent and the neares wall (or flat vertical surface) the vent faces.

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