Jump to content

Triticum Agricolam

Members
  • Posts

    5301
  • Joined

  • Last visited

  • Days Won

    31

Everything posted by Triticum Agricolam

  1. No. That's net volume, which is what's left after you account for sub, port, bracing, etc.
  2. Ok, in that case I'd probably go for a total of 45 sq in of port area. I still thinks Skars recommendation is a little low. Assuming the net volume is 3.5 cu ft total, and you want to tune to 34 Hz, a 45 sq in port is going to need to be around 23-24" long. Keep in mind the layout of the box is going to change how long the port needs to be, but that should get you close.
  3. So, couple questions for ya. You said the subs are dual 2 ohm, are you going to wire 2 ohms to the amp or .5 ohms? How tight are you going to be for space? I assume you are going to go with Skar's recommendation of 1.75 cu ft net per sub tuned to 34 Hz? Since you are running above RMS power (which is fine), you should probably increase the port area a bit from what Skar recommends, but it will take up more space.
  4. Try switching the WinISD graph you are looking at from "Transfer Function Magnitude" to "SPL". The TFM graph is for looking a frequency response, but isn't good for comparing how much output you will get when comparing two enclosures.
  5. The best thing to do would probably be to model the subs in box simulation software. A larger rear chamber will get you more output below your front chamber tuning. It also increases cone excursion though, so it’s going to depend on how much power you are running.
  6. You said you have the box modeled in WinISD? You should be able to see what your front and rear port velocities are in WinISD. When it comes to port velocity, less is better, but larger ports come with their own design compromises. 30 m/sec is my hard limit, if I can get things closer to 22 m/sec that's a lot better.
  7. Sounds like you are off to a good start, just let me know with any specific questions you have.
  8. I'll try to help you as much as I can. First off you need to decide if you want a series-tuned 6th order, or parallel-tuned 6th order. Parallel-tuned boxes are easier to do IMHO, but series-tuned boxes push all the output out one port and that can be useful depending on your situation. The two types are VERY different in how they are designed and WinISD ONLY models parallel-tuned boxes. As far as the port area per cube suggestions you have come across, those are referring to series-tuned boxes and if that is what you decide to build I would strongly encourage you to NOT make the rear chamber small. In my experience making the rear chamber port small will get you a little more middle range output, but at the expense of just destroying your low frequency output. I can show you my testing if you are interested in seeing it.
  9. So the proper way to calculate port length with two ports is to plug the numbers in for one port and divide your box volume in half. So for a 3.2 cu ft net volume box with two 2" x 15" ports you would calculated it like a 1.6 cu ft box with a single 2" x 15" port. In your case, if you are tight on space my suggestion would be to use one port if you can. It takes up less space due to having less internal panels. Also 60 sq in of port area is a bit more than you need. There is nothing wrong with having more than you need and with multiple ports its better to be on the high side for port area since multiples port are less efficient, but if you switched to a single port, 45 sq in (3" x 15") would work just fine. With regards to the SA-15 vs E-15, I didn't see that you were looking at TWO E-15s vs ONE SA-15. Either of those would work well in terms of power handling, but the two E-15s would have needed a box twice as big.
  10. You box net volume and tuning should be fine, though your port length is short if you want to tune to 34 Hz. To tune to 34 Hz I calculate your ports need to be 35" long each. You will have to adjust your external box dimensions to keep the net volume the same. As far as an E-15 vs a SA-15. Here is a comparison of the two in the same size box. SA-15 is the green line and E-15 is the yellow: Their frequency response is pretty similar. Note that this graph is raw output, cabin gain is not included and will boost the low end significantly. Based on the power you are running I think the SA-15 was the right choice.
  11. X8s aren't a good choice for 4th order bandpass boxes anyway. SA8s would work. SA10s would work better.
  12. Go with what fits your space better. All else being equal I'd probably lean toward two 12"s over one 15".
  13. DC recommends 1.5 cu ft per sub. You would probably get more responses if you posted this in the Subwoofer/Enclosures section.
  14. A 2000 watt amp definitely won't be too much for a Xv2, as long as your gains are set right. You could put it on a 3k amp as long as you were paying attention.
  15. The parallel-tuned box should pretty much perform identical on low frequencies to ported box with a similar box specs as the low chamber. So with a 5 cu ft low chamber tuned to 28 Hz the 6th order should be like a ported box with 5 cu ft tuned to 28 Hz. At higher frequencies the 6th order is going to have more output than a ported box because of its second chamber.
  16. A parallel-tuned 6th order has both chambers firing to outside the box, a series-tuned 6th order has one chamber firing its port into the other chamber and then that second chamber fires to outside the box.
  17. So a fourth order bandpass box lets you trade bandwidth for efficiency. So to get the wider bandwidth your friend desires he is going to have to give up a lot of output. My suggestion would be a parallel-tuned 6th order bandpass. You friend would keep the low frequency output he is used to, but he would get a big boost up higher for a much wider bandwidth. For specs I'd suggest 5 cu ft @ 28 Hz for the rear chamber and 2.5 cu ft at 55 hz for the front chamber.
  18. Forget everything you have learned about ratios. They are wrong as often as they are right. You are much better off designing the chambers independently of each other based on what you need the box to do. How much power is your friend going to be running? That will determine how big you can make the sealed chamber. What kind of bandwidth does your friend want to get? What are the goals for the system? That will determine the size and tuning of the ported chamber.
  19. I've bought stuff from the Sundown yard sale on several occasions and have been happy with what I got.
  20. If you have the test leads wired to the inputs going to subs, that is going to tell you total power (both amps combined).
×
×
  • Create New...