Patrick Bateman Posted March 23, 2016 Author Report Share Posted March 23, 2016 I was leaning towards building a front loaded horn with dual Alpine SWS-10D2s. But I found a killer deal on eBay for the JBL 2258H 18". So I bought that instead. I will design a vented box for the JBL, and post it here. It will basically look like one half of this : http://www.jblpro.com/ProductAttachments/ASB6128V.pdf That box looks fairly competitive with the PK Sound CX800. Both are big vented boxes with neodymium eighteens. The JBL features differential drive, which should be good for reducing distortion. The CX800 has more xmax and a larger voice coil, so it will probably get a little bit louder. But the drivers from the CX800 would cost me $700 each, and I just paid $200 for the JBL. Link to comment Share on other sites More sharing options...
Patrick Bateman Posted March 24, 2016 Author Report Share Posted March 24, 2016 I made a tapped pipe for the woofer that mimics the response of the PK Sound CX800. I *think* I'll stick this in my Mazda. It's silly big, but I'm a basshead. The graph above shows the predicted response of the CX800 (grey) and my tapped pipe (black.) Due to the higher qts on the 18Sound 18NLW9600, it's tuned higher than the JBL, which reduces displacement for the CX800. Here's my hornresp model. All the sims are based on a single woofer; double everything to simulate *both* woofers in a CX800. My eighteen will be here on Wednesday. Link to comment Share on other sites More sharing options...
Patrick Bateman Posted March 27, 2016 Author Report Share Posted March 27, 2016 Over at diyaudio, Art Welter pointed out that the xmax on the JBLs isn't so hot. (http://www.diyaudio.com/forums/subwoofers/209053-pk-sound-cx800-95-efficient-13.html) So I gave it some thought, and decided to use my Alpine SWS-15D4 instead. Although the Alpine has less cone area, it has more xmax, so it's displacement is about the same as the JBL. The PK Sound CX800 with it's 18 Sound 18NLW9600 has more displacement than both, but the woofer costs 3X as much. So there's a big price to pay for that last 2-3dB of output. Here's my model of the box. It's a sloped box to fit in the hatch of my Mazda CX5. External dimensions are 24" x 24" x 18" and the internal volume is ninety two liters. I'm building one, but there's enough space in my hatch to fit two. There's a number of innovations crammed into this box. First off, according to JBL, the optimum port shape is like a kidney. ( why aero ports are flared on both ends. In my tapped horn, the entire box is basically a port, and I've flared both ends. This changes the response shape quite a bit; I could honestly get flatter response if I didn't flare the inside end, the space near the woofer. But the reason I went this route is that I want the most undistorted output as possible. I can fix the frequency response with EQ, but I can only get low distortion by maximizing airflow. Another reason I went this route is that I've found that horns with a high compression ratio tend to distort really fast; basically there's too much pressure on the cone. So going with a 'kidney shape' for the tapped horn should reduce that too. The location of the woofer is not accidental; I put the baffle at a 45 degree angle because I want the baffle to act as an 'arch', reinforcing the strength of the two walls it's attached to. Same idea as a Roman arch. The other innovation is that the amp will go in the center of the box, so the airflow from the woofer should reduce the temperature on the amp a little. The main reason I put the amp there is to hide it though. I'm using an Arc Audio 1500DR which is good for something like nine hundred watts. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted March 28, 2016 Report Share Posted March 28, 2016 Looks interesting. I'm curious to see pics of the completed box. "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...
Patrick Bateman Posted March 29, 2016 Author Report Share Posted March 29, 2016 Looks interesting. I'm curious to see pics of the completed box. Thanks! Your boxes look great. If I still lived in Washington I'd probably just have you build me something. I'm good with the keyboard but not-so-good with the table saw. Link to comment Share on other sites More sharing options...
BP1Fanatic Posted March 29, 2016 Report Share Posted March 29, 2016 Hey PB! You know I had to "Set It Off" in your thread! Bass! How low can you go? Death row, what a brutha knowz Once again, back iz the incredible The rhyme animal The uncannable D, Public Enemy # 1... 2000 Toyota Solara SEV6, 200 amp alternator, Jensen VX7020, Hifonics American Warrior Taurus X, Hifonics American Warrior Centurion X, JBL Club 6500C, Power Acoustik XP2K-4102, Coustic Power Logic HT-612 in a BP4. Link to comment Share on other sites More sharing options...
Patrick Bateman Posted March 30, 2016 Author Report Share Posted March 30, 2016 Hey PB! You know I had to "Set It Off" in your thread! Bass! How low can you go? Death row, what a brutha knowz Once again, back iz the incredible The rhyme animal The uncannable D, Public Enemy # 1... I hope I run into Flavor Flav one of these days. I have a house in Vegas and I hear that people bump into him all the time out there. (in Vegas, not my house specifically ) I just realized I have a funny story about this: I was basically the world's biggest fan of PE, back in 1987 or so. A couple of years ago, I was staying at a hotel in Houston and I saw a bunch of guys decked out in PE jackets and gear. For a split second, I was going to ask if they were IN the band. Because who wears Public Enemy jackets in 2014 right? But I re-considered, because I'd feel like a total dumbass if I asked four random dudes if they were in Public Enemy. Particularly since they were just waiting in line for breakfast at the hotel. A couple minutes later I checked on their Facebook page, and sure enough, that WAS them. They played a show the night before. Link to comment Share on other sites More sharing options...
BP1Fanatic Posted March 31, 2016 Report Share Posted March 31, 2016 I saw PE in concert with rundmc, epmd, and dj jazzy Jeff and the fresh prince in 88 or 89. 2000 Toyota Solara SEV6, 200 amp alternator, Jensen VX7020, Hifonics American Warrior Taurus X, Hifonics American Warrior Centurion X, JBL Club 6500C, Power Acoustik XP2K-4102, Coustic Power Logic HT-612 in a BP4. Link to comment Share on other sites More sharing options...
Patrick Bateman Posted March 31, 2016 Author Report Share Posted March 31, 2016 I saw PE in concert with rundmc, epmd, and dj jazzy Jeff and the fresh prince in 88 or 89. Nice! I never saw them the first time around. Didn't catch them until the 'Kings of the Mic' tour, in 2013, with Ice Cube. Link to comment Share on other sites More sharing options...
Patrick Bateman Posted March 31, 2016 Author Report Share Posted March 31, 2016 Here's a couple pics of the box coming together. Not much to look at, but the blood is a nice touch. I put blood, sweat and tears into my projects Link to comment Share on other sites More sharing options...
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