jcody_parker Posted May 6, 2019 Author Report Share Posted May 6, 2019 9 hours ago, Triticum Agricolam said: So on 2000 watts it would be a bit easier to make a ported box work, if you want to give one a try. Since that's not crazy power, you can make the box larger. To have output down to 14 hz I would suggest tuning to about 17 hz. Output is going to drop off fast below tuning and due to the way sound frequencies work 14 hz is a lot farther away from 17 Hz than it seems. Its twice as far away as 29 Hz would be from 32 Hz, even though the numbers are the same. For a ported box, specs I would suggest are 6 cu ft with 60 sq in of port area. The port area may seem on the low side, but the lower you tune the less port area you need. Still the port will need to be about 85" in length (exactly how long depends on the layout of the box). If will be very important that the tuning frequency be accurate, also you MUST have a subsonic filter set to 14 Hz to avoid destroying your sub. Not a lot of amps can set their subsonic filter that low, if your can't I would definitely avoid a ported box. If someone could help out with specs for a 4th order i'd love to build one. Might research into it a little more, I've tried looking but cant find way too much info on it. I figured ported would be more simple but I've never tried tuning this low. I'll get some measurements and try to design a box in SketchUp tonight to see how much room I'm working with. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 6, 2019 Report Share Posted May 6, 2019 1 hour ago, jcody_parker said: If someone could help out with specs for a 4th order i'd love to build one. Might research into it a little more, I've tried looking but cant find way too much info on it. I figured ported would be more simple but I've never tried tuning this low. I'll get some measurements and try to design a box in SketchUp tonight to see how much room I'm working with. Like others have said, with a 4th order bandpass box your lows come from the sealed side. Sealed output is directly related to cone excursion, so you want to allow as much cone excursion as possible without having so much you damage your sub. This comes down to matching your sealed side volume with how much power you are running. With 2000 watts of input power I'd suggest a sealed chamber volume of 2.25 cu ft. You will want to mount the sub so the motor is in the ported side for better cooling. The front chamber is sized to give the frequency response you want. You are mainly going to for lows so there is no reason to make the front chamber huge. 4.0 - 4.25 cu feet is a reasonable place to be. I'd suggest tuning to 42-43 Hz. You are going to want lots of port area since all of your output comes out that port and you don't want to lose any to port compression and port noise is more noticeable on bandpass boxes. I'd suggest 100 sq in of port area. "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: Link to comment Share on other sites More sharing options...
jcody_parker Posted May 6, 2019 Author Report Share Posted May 6, 2019 1 hour ago, Triticum Agricolam said: Like others have said, with a 4th order bandpass box your lows come from the sealed side. Sealed output is directly related to cone excursion, so you want to allow as much cone excursion as possible without having so much you damage your sub. This comes down to matching your sealed side volume with how much power you are running. With 2000 watts of input power I'd suggest a sealed chamber volume of 2.25 cu ft. You will want to mount the sub so the motor is in the ported side for better cooling. The front chamber is sized to give the frequency response you want. You are mainly going to for lows so there is no reason to make the front chamber huge. 4.0 - 4.25 cu feet is a reasonable place to be. I'd suggest tuning to 42-43 Hz. You are going to want lots of port area since all of your output comes out that port and you don't want to lose any to port compression and port noise is more noticeable on bandpass boxes. I'd suggest 100 sq in of port area. I haven't bought a new amp yet. It has no exhaust from the manifold back, one seat, and only a lap seatbelt. So i'll be fixing that first and then buying an amp, and the mids and highs, and then build the box when I have a few days off work in a row. How much power do you recommend putting to it? I figured this guy is throwing 4k at it with the volume on the head unit turned down a little in a huge box, that it would be fine with 2k. So what makes these move a ton of air at low frequencies in a normal ported enclosure? I thought it was big port, big box, tuned low. Link to comment Share on other sites More sharing options...
jcody_parker Posted May 6, 2019 Author Report Share Posted May 6, 2019 I think I'll just do a ported enclosure to keep it simple, most likely a wall since the car is so small and I need room for batteries and the amps in the rear. I like being able to see the excursion right next to you especially with the x15 and its huge surround. I'll post pictures of the area i'm working with. Link to comment Share on other sites More sharing options...
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Triticum Agricolam Posted May 6, 2019 Report Share Posted May 6, 2019 12 hours ago, jcody_parker said: So what makes these move a ton of air at low frequencies in a normal ported enclosure? I thought it was big port, big box, tuned low. Yeah that’s pretty much it, I would also “lots of power” to that list. The hard part is building a box with lots of port area that is tuned low enough, for reasons we have already mentioned. Since you you haven’t bought an amp yet, I would probably go for a 3k if your budget allows. "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: Link to comment Share on other sites More sharing options...
jcody_parker Posted May 7, 2019 Author Report Share Posted May 7, 2019 10 hours ago, Triticum Agricolam said: Yeah that’s pretty much it, I would also “lots of power” to that list. The hard part is building a box with lots of port area that is tuned low enough, for reasons we have already mentioned. Since you you haven’t bought an amp yet, I would probably go for a 3k if your budget allows. So the only way to make a big box with a big port and tune it to 20hz would be to make it several feet in length? I figured there's no "way around it" or something. I was also looking into these - https://www.1800woofers.com/crescendo-audio-contralto-15-subwoofer-2500w-rms/ The xmax is 4mm less and the surround is smaller, but the RMS power its rated at is way higher. I haven't read much about these yet, so I'm not sure if it would be a better choice than the x15 v2. I was going to get the x15 because of the giant surround and amount of excursion at really low frequencies. The Contralto also has a DVC 1ohm option, while the x15 has a DVC 2ohm. I've never seen a 1ohm subwoofer before, wasn't sure if it's just for wiring purposes with multiple subwoofers or if it's any better being lower resistance, because they're the same price. Link to comment Share on other sites More sharing options...
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