Aaskia Posted July 2, 2017 Report Posted July 2, 2017 So I've been fiddling with winisd, sketchup, and all of the different port calculators, and I think I've created the box that hopefully works. Can you guys critique it for me. Its 5.97 cu feet, tuned t0 35 hz (i think) winisd said 10.5h x 10w and vent length 30.07 rear port air velocity was 28 m/s at 34.36hz The subs are (4) SA10 V3 powered by a hifonics brx4016.d I'm sure the box will fit in my challenger.
Triticum Agricolam Posted July 3, 2017 Report Posted July 3, 2017 I think that looks pretty good. Here are a few of my thoughts. 1. Port area and net volume look good for the amount of power you are going to be running. 2. Be sure to set your subsonic filter. 3. The way you have the port implemented its effectively 35" long. WinISD isn't optimized for slot ports and will tune you a bit low as well. If you were to just remove the 5" long pieces from the end of the port that would probably put you right around 35 Hz. You may need to play with your box dimensions a bit to get back to 6.0 cu ft net. 4. Firing subs up in a trunk car can lead to a lot of trunk rattle. Probably isn't much way around that with your setup, but just be prepared to deal with it when it happens. 5. I'd remove the bracing dowels from inside the port. The port is narrow enough you don't really need bracing there and anything in the port can disrupt air flow. "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:
Joe X Posted July 3, 2017 Report Posted July 3, 2017 Ok OP from the figure I take external dimensions are 12x36x30 HxWxD port should be 10X10.5 and 37.5 center line length, your box specs are: Fb = 41.4 Hz Vb = 3.2 ft^3 With 105 square inches of port area. Total driver displacement is 0.4 cubic feet. You are about 0.8 cubic feet net per driver which is pretty low and I wouldn't recommend it. The other thing is subs up on a trunk car, I wouldn't recommend that either due to trunk lid rattling (and loss of output), admittedly, some trunk lids will rattle less than others but generally you want to avoid that. It has been tried successfully subs sideways (two each side), port back. I won't get into the modeling part right now. Seems like your low on space, you should build a card board test box to see what is the largest box you can get inside there before designing anything, it looks like two 12s is more like what you have space for but let's see.
Aaskia Posted July 3, 2017 Author Report Posted July 3, 2017 12 hours ago, Triticum Agricolam said: I think that looks pretty good. Here are a few of my thoughts. 1. Port area and net volume look good for the amount of power you are going to be running. 2. Be sure to set your subsonic filter. 3. The way you have the port implemented its effectively 35" long. WinISD isn't optimized for slot ports and will tune you a bit low as well. If you were to just remove the 5" long pieces from the end of the port that would probably put you right around 35 Hz. You may need to play with your box dimensions a bit to get back to 6.0 cu ft net. 4. Firing subs up in a trunk car can lead to a lot of trunk rattle. Probably isn't much way around that with your setup, but just be prepared to deal with it when it happens. 5. I'd remove the bracing dowels from inside the port. The port is narrow enough you don't really need bracing there and anything in the port can disrupt air flow. What would you recommend setting the subsonic filter to? I removed the 5" pieces and the dowels. If i increased the height of the box to get back to 6.0 cu ft, how does that effect my port size. I can take my height up to 16", and i can also reposition the subs on the side of the box and still have the port fire towards the rear. I tried to contact woofersetc to return the 10s for 2 12s, but he denied my return request, even though it hasn't been 30 days. So looks like I'm stuck trying to make it work.
Aaskia Posted July 3, 2017 Author Report Posted July 3, 2017 5 hours ago, Joe X said: Ok OP from the figure I take external dimensions are 12x36x30 HxWxD port should be 10X10.5 and 37.5 center line length, your box specs are: Fb = 41.4 Hz Vb = 3.2 ft^3 With 105 square inches of port area. Total driver displacement is 0.4 cubic feet. You are about 0.8 cubic feet net per driver which is pretty low and I wouldn't recommend it. The other thing is subs up on a trunk car, I wouldn't recommend that either due to trunk lid rattling (and loss of output), admittedly, some trunk lids will rattle less than others but generally you want to avoid that. It has been tried successfully subs sideways (two each side), port back. I won't get into the modeling part right now. Seems like your low on space, you should build a card board test box to see what is the largest box you can get inside there before designing anything, it looks like two 12s is more like what you have space for but let's see. What if I increased the height another 2 inches. That would also allow me to mount the subs on the side, versus the top.
Aaskia Posted July 3, 2017 Author Report Posted July 3, 2017 This is the look that i was going for. Lol.
Triticum Agricolam Posted July 3, 2017 Report Posted July 3, 2017 51 minutes ago, Aaskia said: What would you recommend setting the subsonic filter to? I removed the 5" pieces and the dowels. If i increased the height of the box to get back to 6.0 cu ft, how does that effect my port size. I can take my height up to 16", and i can also reposition the subs on the side of the box and still have the port fire towards the rear. I tried to contact woofersetc to return the 10s for 2 12s, but he denied my return request, even though it hasn't been 30 days. So looks like I'm stuck trying to make it work. The general rule for subsonic filters is to set them to 1/2 octave below tuning. To figure that you just multiply your tuning frequency by .75, so it your case it would be roughly 26 Hz. If you make the box taller you will need to make the port a little narrower just to keep the port area the same. As far as having your subs firing out the sides, I have never done it that way myself, but I don't see how it can be any worse than firing them up. I'd be curious to see if anyone else chimes in with experience on that situation. "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:
Aaskia Posted July 3, 2017 Author Report Posted July 3, 2017 48 minutes ago, Triticum Agricolam said: The general rule for subsonic filters is to set them to 1/2 octave below tuning. To figure that you just multiply your tuning frequency by .75, so it your case it would be roughly 26 Hz. If you make the box taller you will need to make the port a little narrower just to keep the port area the same. As far as having your subs firing out the sides, I have never done it that way myself, but I don't see how it can be any worse than firing them up. I'd be curious to see if anyone else chimes in with experience on that situation. Ok I redesigned the box. How does this look?
Joe X Posted July 3, 2017 Report Posted July 3, 2017 That looks very much improved: 6.1 net @34.8Hz with 101.5 square inches of port area, questions remaining: if it can fit in it's way inside once built and if you have proper port clearance, it's still subs up so you are likely to get the rattling issue.
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