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Triticum Agricolam

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Triticum Agricolam last won the day on June 18

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About Triticum Agricolam

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    Eastern Washington State
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    Speaker enclosure design & construction

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  1. Triticum Agricolam

    Bandpass for 8" woofer?

    I know this is a center console box, but the gross volume you have available is enough for a single ported 12" or possible a pair of ported 10"s. If there is anyway you can make either of those options work you will be way ahead. A ported 12" will stomp all over any 8" bandpass box or three 6" ported subs. Subs smaller than 10"s are for when you absolutely can't fit anything bigger.
  2. Triticum Agricolam

    Enclosure for Sundown Audio X-15 v.2

    High aspect ratio ports increase port air resistance, but that's not as much of a problem if you can keep port velocities low. It would be best to avoid the high aspect ratio port but as long as you make the port nice and large so airspeed is low, it shouldn't be a problem.
  3. Triticum Agricolam

    Enclosure for Sundown Audio X-15 v.2

    The smoother frequency response of the OA-18 is what I find most appealing about it. The extra efficiency it has is very nice too. While you can get louder with the X-15 over a limited frequency range, its going to take a LOT more power to do it. In the end, you have to decide which will make YOU the happiest. Neither choice is right or wrong, it just depends what is going to work best for you. Smooth frequency response is important to me, but that doesn't mean it has to be important to you.
  4. Triticum Agricolam

    port tuning

    Four ports 6" in diameter and 30" long should tune you to around 35 Hz. If you are after peak performance you would be better off with one or two larger aero ports though.
  5. Ok, so you are going to get the most power compression at the frequencies where you impedance is the lowest. Thats going to be right at your tuning frequency and then you are impedance is going to get pretty low again up above around 70 Hz (depending on your sub). Right at your tuning frequency is where you will get the most port compression as well. Measuring at your tuning frequency is going to tell you how much total compression you are getting and that's what I assume you care about the most. Starting a low volume with a sine wave tone at your tuning frequency, you want to measure your output and record the number. Using a DMM measure the output voltage out of your amp as well. From there you want to keep increasing power and taking measurements. Increasing power in 3dB increments usually works well. A 3dB increase in output requires a 1.413x increase in output voltage. So play with your volume to increase the output voltage from your amp by 1.413x. You will notice that a 3db increase in output voltage isn't going to get you a 3db increase is SPL. The difference is how much compression you are getting. Be careful when you are doing this, sine wave tones take a lot of power and will heat up your coil pretty fast at higher volume levels. Obviously you want to be care not to send your subs a clipped signal either.
  6. Triticum Agricolam

    Enclosure for Sundown Audio X-15 v.2

    If it were me, I'd stick with the OA-18.
  7. To test you need to be able to measure SPL and/or impedance at different power levels and frequencies.
  8. You can test for total compression (power and port compression together) pretty easily. Determining how much compression is port and how much is power is a little more challenging.
  9. Triticum Agricolam

    8th order? I need help understanding/deciding/designing

    You can using a single port with both a 4th order and 6th order enclosure. There are almost no 8th order enclosures in use in car audio and there is a good reason for that. The benefits (if any) aren’t with the complexity. I’d suggest a 4th order bandoass box for those JL subs.
  10. Triticum Agricolam

    Will this box design work????

    Hey man, I've been meaning to get back to you. I'm right in the middle of my busiest season and I'm working like 70 hours a week, so I just haven't had time. Figuring out just how the box you have laid out is going to affect your tuning takes an amount of time that I just don't have right now. I can tell you this though, its going to lower your tuning a bit, you might tune a couple Hz higher to compensate.
  11. Triticum Agricolam

    Obsidian Audio 18 Enclosure Assistance

    Sorry I haven't responded earlier. I'm in the middle of my busiest time of year and I just don't get much time to get back to people. Regardless of how you arrange your port, your box should be braced internally. Here is a post I made on bracing techniques: Your box specs of 5.25 cu ft net tuned to 28 Hz with ~62 sq in of port are should be fine. One thing you might do with your current box is verify the tuning frequency. Sounds like it might have come out higher than you intended. You can verify your tuning frequency by playing sine wave tones at moderate volume while watching/lightly feeling your cone. Adjust the sine wave frequency up and down until you reach the point were cone movement is at a minimum, that will be your tuning frequency.
  12. Triticum Agricolam

    Will this box design work????

    Having your port configured like that will almost certainly affect the tuning frequency. Without knowing the full dimensions of everything I can't tell you how it will effect it.
  13. Triticum Agricolam

    Obsidian Audio 18 Enclosure Assistance

    I wouldn't lose sleep over the weak motor thing. Its not an uncommon situation for many 18" subs and the OA18 you have will still be louder than the SA-15 would be in every single way. Its just what happens when they use the same motor for the 10", 12", 15", & 18" subs in a product line. The 10" subs end up having too strong of a motor and the 18"s end up a little weak. As far as your first proposed box specs go I think you will be fine. You are right, I don't like the aspect ratio of your ports, but you have enough port area that it shouldn't matter. With a 22.75" wide port I'd suggest putting a brace piece in the middle to keep the panels from flexing. Bracing is a important thing to consider with a box the size of yours, regardless of your port dimensions. Your second box specs do have a much better port aspect ratio and I'd prefer the lower tuning, but if you think the first box with ports on each side will make you happier, I would go with it.
  14. Triticum Agricolam

    Obsidian Audio 18 Enclosure Assistance

    The OA18 sub has a bit of a weak motor for the amount of cone area it has. This causes its output to begin to roll off on the bottom end at a bit higher frequency than other subs might. My suggestion would be to tune a bit lower (say 30 hz or so) and make the box as large as your space will allow. 6 cu ft net would be great, but it you can't get that much it will be OK.
  15. Triticum Agricolam

    first time trying to build a box

    What does the sub do?
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