timkirkland1 Posted September 18, 2008 Report Share Posted September 18, 2008 (edited) Hey guys, I have been building boxes for a few years now, not that often, only when friends want me to. I have been using BassBox, or just building them to what the spec sheet says to. So I am by far not very good at it. But wanting to learn. Anyway, I just finished a box for 3 15" MTX subs in the back of a friends EXT. I just built it according to the spec sheet that comes with the subs. I made 3 seperate chambers, mainly to help with bracing. I only used 3/4 MDF everywhere. After it was done I thought mabe I could get more out of them. Reading on here I hear everyone talking about tuning it to 35 Hz. Not sure how that's done and was wondering if anyone could shed some light on an eager novice. It hits pretty hard, but seems like it should be more for 3 15s. I think the model number for the subs is TR7515-44, and he is running the Memphis MoJo amp, I think he said it is rated at 2200 at 1 Ohm, though i think they are running at a little over 2 ohms, some how, my wiring expert buddy says they are wired in parallel series or series parallel to 1 ohm, but I don't think so for some reason. Which if some one could explain if thats even possible would help too. my friend is not a good teacher. Edited September 18, 2008 by timkirkland1 Quote Link to comment Share on other sites More sharing options...
timkirkland1 Posted September 18, 2008 Author Report Share Posted September 18, 2008 Hey guys, I posted this kinda late last night so I wanted to bump it up to see if some one can help me with the tuning of a box and how it's done. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
ptcary Posted September 18, 2008 Report Share Posted September 18, 2008 (edited) Tuning a box to a specific frequency requires a port of proper size and volume, and also specific airspace for each sub. Do you know what the box is tuned to right now? I would start with getting someone who really knows how - to double check the wiring to see what the ohms really are, and also check them for phase issues. Nothing against your wiring guy, but 3 subs can get confusing especially if they are dual voice coil. Next is the truck supplying enough power to feed those amplifiers? Also, general setup comes to mind. I am getting more and more out of my new setup each time I do more adjusting with it. Edited September 18, 2008 by ptcary Quote PTCary 2003 SMD PT Cruiser 2011 Honda CBR 250R 2010 Mazda 3i Sport MY BUILD LOG Link to comment Share on other sites More sharing options...
dmanson Posted September 18, 2008 Report Share Posted September 18, 2008 are the subs dual 2s or dual 4s? Quote 2-DC 15XLM2 D.7s 1-DC 5K amp (1) XS Power D6500(UNDERHOOD) and (1) XS3000(REAR) 3 runs 1/0ga for power and 2 runs of 1/0ga for negative. (2)-RFT165s components, ...... 4 separate 1 inch tweetersRF T600-2(fronts) Punch 450.4(rear) Audiocontrol 3.1. DC power 260amp alternator w/MLA Module Link to comment Share on other sites More sharing options...
timkirkland1 Posted September 18, 2008 Author Report Share Posted September 18, 2008 (edited) The subs are dual 4's. He is also running 2 kinetic batteries out back to help with power. I don't know what its tuned to right now, basbox said it would hit 125 at 60Hz....??? and thats just one chamber w/ 1 15....but don't know how acurate bassbox is.....especially when i probably don't know how to use it right. I've learned alot just reading through this forum, there are alot of smart people on here and I am just happy so many are willing to share their knowledge. Moving to the phase issue, i have the subs all in their own chamber, would I still get phase issues running them like that? here is the box design.... Edited September 18, 2008 by timkirkland1 Quote Link to comment Share on other sites More sharing options...
Boon Posted September 19, 2008 Report Share Posted September 19, 2008 How long are those ports? I don't really understand the cut sheet.... Quote 10.x volts fo' life! Link to comment Share on other sites More sharing options...
timkirkland1 Posted September 19, 2008 Author Report Share Posted September 19, 2008 (edited) The ports are 2w x 14h x 15.90625L, the box is 2.99 ft3 before adding speakers. I just figured out what is is tuned to and I came up with 63.97806. So if I would have made the ports shorter, that would lower my tuning freq, which would make it louder?? If I am understanding everything I am reading. Or do I need to make them longer? Edited September 20, 2008 by timkirkland1 Quote Link to comment Share on other sites More sharing options...
timkirkland1 Posted September 19, 2008 Author Report Share Posted September 19, 2008 To tune it to 30Hz I got vent length of 10.925603", can any one verify for me??? I am horrible at math. I used the equations at JLaudio.com http://mobile.jlaudio.com/support_pages.php?page_id=165 Quote Link to comment Share on other sites More sharing options...
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