Ok, this was a huge pain in the ass to get so sorry it took so long. I had to fire up the barely working laptop to retrieve the file, save it to a USB, transfer it to my working but slow old laptop, download a PDF converter, and finally post it up here. Please take at look at the attached PDF file with all the pertinent information used in the model I used. I checked the velocities and I get the following velocities with associated watts.
37.7 m/s @ 31.14 Hz @ 2000 watts and 118.1 db
32.6 m/s @ 31.14 Hz @ 1500 watts and 116.8 db
26.6 m/s @ 31.14 Hz @ 1000 watts and 115.1 db
18.8 m/s @ 31.14 Hz @ 500 watts and 112.1 db
David, Its been two months since I worked on this so please check the box dimensions and make sure I got them right. We went through about 10 different designs and I don't remember if this is the correct one or not but they also didn't differ much either. Also consider the above power levels. I believe 90% of the actual musical powered used will be under 1000 watts unless David is into SPL lanes and burps. Even at just 500 watts this thing is over 112 db at 31 Hz so it gets even louder up higher.
Mazda CX5 AF GB10, AF GB25, AF GB60, JL VX800/8i, AF GB12 sealed, Mmats M1400.1
Ford F150 AF GB10, AF GB25, JLC5, JL twk88/Pioneer D8604, Mosconi Pico, JBL Club 5501, Sundown SD3-10 ported @ 30 Hz
Sienna AF GB15, Audiofrog GS690, JL twk88/Pioneer D9500F, JBL GTX500, Alpine SWS10 ported @ 31 Hz
https://www.diymobileaudio.com/threa.../#post-5608901
Thanks, John!!! The design I posted was the final one... I checked our pms thoroughly.
2019 Jeep Wrangler 2 Door - Morel Elate 3 way, Mmats HiFi 6150 & M2000.2, Hutchinson NDFEB 10", MiniDSP w/DL, Fiio X5
#TRUMP2020
Me too, John. I hate to think this was all for naught.
The one in the attached pdf appears to be identical in every way except for a very slightly larger cabinet volume than the one you posted (1.361 ft^3 vs 1.354 ft^3). I highly doubt this +/- 0.007 ft^3 would make any practical difference.
Shit... I read the calculator wrong, SMH... it's 22.6 in^2 per ft^3... optimal is listed as 31 in^2 (again, based on 1.36 ft^3, 33 hz at 1 kW)... and minimum is listed as 23 in^2. However, as this calculator is meant to be only a rough guide, and not at all a replacement for modeling, I agree that our best bet would be to rely on your Bass Box modeling results.
https://docs.google.com/spreadsheets...gid=1632976665
Guys, I just found and read the PM correspondence we had a few months ago and it’s all coming back to me now. We discussed the compromises in regard to port velocity, SQ goals, box size, and port size. We had constraints like box size and orientation that I had to abide by so some compromises had to be made. I still think given these constraints we have a best case compromise assuming this is mostly a SQ system that will be used with modest power (under 1300 watts on music) but with the capability to go SPL. We didn’t design this thing to have max volume at 2000 watts without some possible port noise (if you actually hear it at this volume).
below I cut and paste some conversation messages we had:
That is correct David. I went back and changed it and then I checked the vent velocity and it is a little bit too high for my liking. The issue I have with it is that if you actually put 2000 watts to this subwoofer (not likely but possible) then you may experience port noise due to the velocity being too high. If you keep it under 1350 watts then you are ok. I can fix this but the compromise is the box has to get bigger or the port has to get bigger and much longer (over 40") and I'm trying to avoid another bend in the port. Please take a look at the marked up PDF I'm sending with answers to your questions and also copies from the BassBox Pro manual with definitions. Please pay close attention to the vent velocity and then advise me on which direction you want to go. I can push the box size back up to your max dimensions again but I'm trying not to do that and I'm also worried about the power handling going down as well. Good thing about going bigger though is that bottom end response goes up with less power. If you look at the cone displacement though you are within the XMAX of the subwoofer even on 2000 watts and even if I increase the size of the box.
Since that post I modified/tweaked it a little bit and I found this design attached in the personal messages that I believe was the final design. DavidRam final box design with 16 sq ft of port area.pdf (revision 1).pdfDavid,
I think I finally nailed your box design to get the ideal 16 sq inches per cu ft of box volume for the best compromise between SPL and SQ. The program is predicting a tuning frequency of 33.48 Hz but the end of the port should be within 3" of the end of the box at the inside corner if I did my math right so that should lower the tuning a little bit just because of that. I had to max out the box dimensions according to what you gave me to get the size of the port and port area just right so the net volume will be 1.321 cu ft if you recess the subwoofer flush with the surface, install 2 braces, and make the port opening exactly 1.875 x 10.5 " and not be off with that measurement even 1/8". You are going to have to build this box exactly as shown so that the port area and box volume end up exactly per the drawing. If the volume is off (smaller) or the port too big then the tuning will go up and I'm at the top of where I like the tuning to be. Please see attached PDF and I will follow up with a sketch of my own so that we are on the same page.
Your only other options would be to make the port partially external, go with a triangle port (I can model those too), go with less port area and compromise possible SQ, or make the box bigger. I feel like I designed a pretty decent box with those size constraints for a 2000 watt subwoofer when before I just didnt like the fact that the port velocity was so high. Now its at an acceptable limit.
Please read page #10 here about vent velocity. These are the guidelines that I use when factoring in how much m/s I can push up to.
David Ram Box 3.pdf
Mazda CX5 AF GB10, AF GB25, AF GB60, JL VX800/8i, AF GB12 sealed, Mmats M1400.1
Ford F150 AF GB10, AF GB25, JLC5, JL twk88/Pioneer D8604, Mosconi Pico, JBL Club 5501, Sundown SD3-10 ported @ 30 Hz
Sienna AF GB15, Audiofrog GS690, JL twk88/Pioneer D9500F, JBL GTX500, Alpine SWS10 ported @ 31 Hz
https://www.diymobileaudio.com/threa.../#post-5608901
Ok, thanks John!! I'll use the above specs and start building the box today. I tired to read page #10 above, and my brain died... Lol
2019 Jeep Wrangler 2 Door - Morel Elate 3 way, Mmats HiFi 6150 & M2000.2, Hutchinson NDFEB 10", MiniDSP w/DL, Fiio X5
#TRUMP2020