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Triticum Agricolam

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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. You would probably have better luck with this thread if you posted it in the “Subwoofers/Enclosures” section.
  2. Sounds like you have plenty of port area. There probably are no easy solutions to getting louder if you don't want to go to a much larger box and more cone area.
  3. The OP has had six different people unanimously agree he shouldn't use a PSU and car amp for home audio. How much you want to bet he does it anyway?
  4. There isn't a better deal. Using car audio amps in a home audio environment is nearly always a convoluted and unreliable mess. Plate amps are cheap up to about 250 watts, from there the Behringer pro audio amps offer a really good bang for the buck. If you shop around you can probably find a 1000 watt Behringer amp for around $200 and you won't burn your house down.
  5. I've been watching these on GunBroker for a couple months now, finally snagged on for a price I was happy with. One of my shooting buddies is a Kel-Tec hater, contrary to his opinion this thing is built to a MUCH higher standard than Kel-tec stuff of the past. I'm excited to get out and shoot it.
  6. I would use a roundover bit on a router, if you have one available, to try and give it a bit of a flare. If you can't do that at least try to break the sharp edge by hand. The 7.25 internal diameter tube may be just fine. With either you are going to have to adjust the length of your port to get the tuning you want compared to an actual 8" internal diameter port. If the 9.25 port will fit that would be great. I'm just concerned it will have to be so much longer to get the tuning you want that it won't be practical.
  7. If you used 4" ports instead of a single 8" you would need four 4" ports to equal the same port area, they would have a lot more internal surface area though, so they would be less efficient. (This is why its not best to use more than one or two aero ports). You don't need to use pipe to make an 8" port, just get some 8" concrete form tube. They should have it at Home Depot, Lowe's, etc. Bring your tape measure with you though, what's labeled at an 8" tube can be anywhere from 7-9" internally.
  8. Its not exactly light reading, but I've found this AES paper to be very informative: http://mariobon.com/Articoli_storici_AES/jbl/JBL_2002_AES_Reflex_Ports.pdf If you need any help with WinISD just let me know. There are a lot of older versions of it floating around, but if you get the newest version (0.7.0.950) its a lot easier to use.
  9. Did you cut the kerfs on a table saw or with a handheld circular saw?
  10. SPL output around tuning is going to directly correlate to box pressure. There are four things that increase port velocity - increasing box volume, increasing input power, increasing the tuning frequency, or decreasing port area. The opposites of those four will decrease port velocity. Probably the best thing for you to do at this point would be to get some box modeling software (WinISD is free and works well). With that you can play around with box parameters and see what effects they have on port velocity.
  11. How much space do you have to work with? My general philosophy is to use as much cone area as you can properly fit in the space you have available. The L7 15 has a LOT more cone area than the Alpine 12, but it will need to be in a MUCH bigger box.
  12. If the boxes you tried before were prefabs, its not uncommon for them to have very little port area, as well as being tuned high. That would explain the poor low frequency performance you had. For a new box I'd suggest 2 cu ft net tuned to 32 Hz with no less than 30 sq in of port area.
  13. Yes, there is a formula that will help you keep your port velocity at reasonable levels. ckeeler11 posted a link to the thread where I discuss the formula I developed. A couple things to keep in mind, tuning frequency has a big impact on how much port area you need, in addition to box volume and input power like you said. Higher tuning frequencies need more port area than lower ones do. Excursion has pretty much no impact on how much port area you need however. This is because the frequencies where port velocity is highest is generally around the tuning frequency. This happens to be where cone excursion is at a minimum. This is also why reducing port area is a almost completely ineffective way to try to reduce cone excursion.
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