DaileyH Posted January 16, 2015 Report Posted January 16, 2015 I have a JL 12W1v2-4 and I'm looking to build my first 4th order for it. I have everything I need I'm just having a little trouble designing it because I don't have access to anything other than my iPhone so I can't use most programs. I'm looking for a 1:2 enclosure. Something not extremely big in size though. I wanna play just below 30 hz and around 65 hz that's pretty musical without much peak. When I used the online calculators using the subs specs it would tell me the sealed side is bigger than the ported side. I've always been told the ported side needs to be bigger. Can someone please help?!
Triticum Agricolam Posted January 16, 2015 Report Posted January 16, 2015 When it comes to bandpass boxes, there really aren't any hard rules that apply to every situation. So just because you think you want 1:2 box with the ported chamber the bigger of the two doesn't mean that is what is going to work out best. With a 4th order bandpass box the rear chamber largely determines how low you can play, the bigger it is, the lower you can go. The front chamber determines how high you can play, the higher it is tuned, the higher you can go. But if you tune too high you will get a dip in your response between the low end and the high end. The size of the front chamber determines how much boost you get around tuning. If you make it too big you will get a big peak at your tuning frequency and your box won't sound right. Too small and you won't have any mid bass. I played with the numbers and the best thing I could come up with was 2 cubes sealed, 1.5 cubes ported at 50 Hz. That will probably give you what you are looking for. However I compared that bandpass box to what you would get with JL's recommended ported box of 1.75 cubes at 28 Hz and personally I'd just go with the ported box. The bandpass box only gained you about 1-2 db over its entire range. That's not worth it for a box that is twice as big and three times as hard to design and build, at least in my opinion. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
DaileyH Posted January 16, 2015 Author Report Posted January 16, 2015 I'm just building this for the experience, not looking for major gains. I've built ported boxes and they've turned out great, just looking to get a hands on approach to 4th orders now. So it shouldn't matter that my sealed side is bigger? That was my main question. All the 4th orders I've seen had the ported side bigger. I've done a lot of research, but no one seems to touch the subject of what if your sealed side is bigger. Are those calculations facing the port inside the box or outside?
Triticum Agricolam Posted January 16, 2015 Report Posted January 16, 2015 It does matter that the sealed side is bigger, its quite important, what I'm trying to tell you is that its not wrong that the sealed side is bigger. The numbers I have you are net airspace for each side. You will have to add your sub displacement and port displacement to those numbers. Designing this box w/o a computer where you can use SketchUp or something is going to be quite the challenge. If you are mainly building this box to learn I'd suggest you design it in such a way that the port is removeable or otherwise adjustable so you can play with port tuning a bit. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
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