luism1983 Posted June 10, 2014 Author Report Share Posted June 10, 2014 Truth to that is never ideal , I think I am gonna go with the square port I got an idea on how to set the port is gonna be partly internal and external just gotta go home and draw it out, thanks for the help audio fanatic Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted June 10, 2014 Report Share Posted June 10, 2014 No prob, let us know how it goes! "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...
luism1983 Posted June 10, 2014 Author Report Share Posted June 10, 2014 May I ask how did you come up with port lengths ? Just so I can understand If I raise my tuning to 45hz my port will be shorter? Thinking of using the 5 x 10 port audio fanatic Link to comment Share on other sites More sharing options...
Krakin Posted June 10, 2014 Report Share Posted June 10, 2014 Less port area = lower tune More box volume = lower tune Longer port length = lower tune ---------------------------------------- More port area = Higher tune Less box volume = higher tune Shorter port length = higher tune Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted June 11, 2014 Report Share Posted June 11, 2014 May I ask how did you come up with port lengths ? Just so I can understand If I raise my tuning to 45hz my port will be shorter? Thinking of using the 5 x 10 port I use my super-secret port length formula and excel to determine port length. If you are willing to use a slot port, a 5 x 10" slot port will get you the most area and won't really use any more volume since it will have three common walls. I would recommend against tuning to 45 Hz. Below the tuning frequency your enclosure loses it ability to control cone movement. If you try to play too much below your tuning too loudly you can smack your coils into your backplates and then you will be re-coning your subs. Of course you can set your subsonic filter on your amp high enough to protect you from this, but then you will lose out on your low bass. ETA: When you tune higher you start needing more port area if you want to avoid port noise, also with a higher tune you can start getting a bigger hump in your frequency response, which is not what you want if you are concerned about sound quality. "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...
luism1983 Posted June 11, 2014 Author Report Share Posted June 11, 2014 Learn something new , thanks great info So port should be 26" long 10" wide and 5" high ? audio fanatic Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted June 11, 2014 Report Share Posted June 11, 2014 Learn something new , thanks great info So port should be 26" long 10" wide and 5" high ? Yup, that should tune you right to 40 Hz. "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...
luism1983 Posted June 11, 2014 Author Report Share Posted June 11, 2014 Which side should I put it on drivers side or passenger side? If it makes a difference audio fanatic Link to comment Share on other sites More sharing options...
bbeljefe Posted June 11, 2014 Report Share Posted June 11, 2014 If the box is going in the van you pictured, it shouldn't matter if the vent is to the left or right. You mentioned that you like to do single sub ported boxes because that's less confusing for you where ports are concerned. Here's a simple tip... if one sub needs one 3" vent, then 4 subs will need four 3" vents. Likewise with box volume. If one sub needs 1 cube, then four subs need 4 cubes. Also, here's a much simpler way to accurately calculate total box volume before you go to the cutting table. If I were charged with building a box for 4 Meso 8s the process would be thus: First, if my tuning is supposed to be 40Hz I would build the box on the small side of recommended volume. For lower tuning, I'd move that to the larger size but let's keep in time with your design. CT recommends a minimum of .5 cubes for the Meso 8 and we have 4 so, I need 2ftⁿ of net enclosure volume. I also have to account for sub and vent displacement so I start with 2 cubes and add .08 x 4 for sub displacement... 2.32ftⁿ. Next, I need ~12.5"² of vent per sub or, 50"² of total vent area. Again, in keeping with your design. I can use a vent calculator like this one to find my vent length. I enter 2ftⁿ, since that's my total net volume and that tells me my vent needs to be 31.27" (rounding to 31.25 for ease of measurement won't hurt). If my internal vent wall is .5" material, then I calculate 5.5 x 10 x 31.25 for a total vent displacement of .99ftⁿ. Once I know all of my displacements and my desired net volume, I add them together so: 2ftⁿ net volume + .32ftⁿ sub displacement + .99ftⁿ vent displacement = 3.31ftⁿ gross internal volume. That's how big the box has to be in order that my tuning be accurate. Now that I know that number, I go to my dimensions and choose the two that are not variable. Normally, that's width and height but in the case of the van, I'd think width and depth are more critical so that's what I'll use to find what height I have to have. Assuming your 1" thick material I'll calculate using internal dimensions of 38.5 wide and 14.5 deep: Gross box volume of 5719.68inⁿ ÷ 38.5 ÷ 14.5 = 10.24, which would be my internal height. I'd round to 10.25 and my overall height would be 12.25". One problem with the above calculation is that the Meso 8 has a 6.6" mounting depth and with the slot vent we're using, that would only leave .85" between the bottom of the motor and the top of the vent on three of the subs. Since we need at least a pole vent's width behind the subs for proper cooling, I'd have to adjust either the width or depth of the box by ~.5" in order to accommodate that need. Lastly, I'll echo an above poster in saying, nice work man. The box looks good and should sound good with the venting Triticum offered. Facebook: facebook.com/audioanarchyllc Instagram: audioanarchyllc Youtube: youtube.com/bbeljefe Link to comment Share on other sites More sharing options...
luism1983 Posted June 11, 2014 Author Report Share Posted June 11, 2014 Great info thanks, so if I add another 1/2 sheet to the baffle it would make it 1-1/2" witch will raise the speakers 1/2" and that should be enough room to keep the subs cool? audio fanatic Link to comment Share on other sites More sharing options...
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