Woofer Pressure Posted September 15, 2014 Author Report Share Posted September 15, 2014 Thank you for the input so far. Any other thoughts? I modeled the box in WinISD and got a peak port velocity of almost 27 m/s which I believe is pretty high, and the 180 turn won't help either. Any other port designs you can think of that might work better? Use a different software and you will likely get a different peak airspeed so yeah, your area is around to what Sundown gives tuned to low 30 so you can't be so off, anyways I noticed a couple of things with your port, 1- the total area of the internal end is lesser than the one on the external end, that's not standard ported for it to be, both total areas should be equal, 2 - your box is almost 29" and your port is 6 wide, minimum external clearance would be 6" soo you have that?? The following is a pic showing what a standard port would look like and proper areas and external clearance shown: The port width is a drawing error on my part. The large width should be 5.5 inches and the 2 smaller widths should be 2.75 inches each. Does that sound right? Another way I could build the port is like this: Not sure if the air resistance would be any better this way or the same as before. Also it is not symmetrical which might be bad. And yes, I do have just 6 inches of clearance on the external end. Is that enough space for a 12 inch sub? I pushed my current box 6 inches away from the back of the trunk to test this and didn't notice anything bad. Link to comment Share on other sites More sharing options...
Joe X Posted September 15, 2014 Report Share Posted September 15, 2014 I don't see any major issues with your first port but if you do it like your last drawing, fold vertically so that there's a better chance that subs load the same. To be clear, like your last drawing was a side view rather than a top view. Link to comment Share on other sites More sharing options...
Woofer Pressure Posted September 16, 2014 Author Report Share Posted September 16, 2014 I don't see any major issues with your first port but if you do it like your last drawing, fold vertically so that there's a better chance that subs load the same. To be clear, like your last drawing was a side view rather than a top view. Ok, that makes sense. Link to comment Share on other sites More sharing options...
Woofer Pressure Posted September 18, 2014 Author Report Share Posted September 18, 2014 I've been playing around with your Sketchup file a bit. I'm really busy and haven't had a chance to finish what I started, but if you give me a couple more days I'll post back with my suggested changes. Great, I'm looking forward to seeing what you come up with! Link to comment Share on other sites More sharing options...
magillaru Posted September 20, 2014 Report Share Posted September 20, 2014 Interested in thoughts on how much of an impact different port areas would have on output/response since your essentially changing the overall net volume? I'm assuming not too much as long as your not making any drastic changes......and I would assume it would be better to end up with more volume vs less after any changes? Singer Alternators Team Asshole #anothershittysingerbuild Link to comment Share on other sites More sharing options...
Woofer Pressure Posted September 20, 2014 Author Report Share Posted September 20, 2014 Interested in thoughts on how much of an impact different port areas would have on output/response since your essentially changing the overall net volume? I'm assuming not too much as long as your not making any drastic changes......and I would assume it would be better to end up with more volume vs less after any changes? The box design that I made here is around 4 cubic feet after all displacements when tuned to 32hz. A 32hz port is 1.25 cubic feet displacement. A 28hz port for example would be 1.7 cubic feet while a 40hz port is only .7 cubic feet, so the airspace does vary quite a bit. With a higher tuned port you could just put something in the box to take up volume and keep the box at 4 cubes, but you will lose some airspace when tuning lower. I think the proper way to do it would be to build the box larger to begin with and just have some pieces of wood or something always in the box that you can remove to raise airspace when tuning lower. I just don't have the room for a larger box in my car. I'm not really sure if a 3.5 cubic foot box tuned to 28hz would be a problem for these subs or not... Link to comment Share on other sites More sharing options...
magillaru Posted September 20, 2014 Report Share Posted September 20, 2014 Yeah, it will definitely make a difference if you're drastically changing between low and high tuning (then again, I guess if you're only changing between a couple Hz, is it worth the effort? Maybe if you're up in the air about the exact tuning you want and you would like to be able to dial in to what you think works best....). I agree with starting off with a larger box volume and then using pieces of wood or something else to make up for the extra space but I don't know if I would want random pieces of wood floating around inside the box especially if this is for a daily setup. *I'm also getting ready for a new build soon and considering doing a removable port so I was curious to see what others thought on this. Singer Alternators Team Asshole #anothershittysingerbuild Link to comment Share on other sites More sharing options...
Woofer Pressure Posted September 25, 2014 Author Report Share Posted September 25, 2014 Any progress Triticum? I'm itching to get this thing built. If the removable port is not possible, I guess I can live with a standard slot port. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted September 25, 2014 Report Share Posted September 25, 2014 Yeah, sorry it has taken me so long, I've been really busy lately. Anyway, here is what I came up with. I think JoeX had the right idea with folding the port vertically, so I ran with that. As I have it now it only has one 90 degree bend and you have just over 56 sq in of port area. With all those angled pieces along the sides this is going to be a fairly difficult design to build. You will need some internal bracing as well. I put four 1-1/2" dowels running from the bottom panel to the top, that's just a start though. I would recommend you do some additional bracing. You will want to roundover all the port edges for good air flow and make sure however you attach the remove-able port that it seals up well. Its doesn't take much of a leak to ruin the performance of a box. Here is the SketchUp file: https://dl.dropboxusercontent.com/u/1642665/Subwoofer%20Enclosure.skp "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...
Woofer Pressure Posted September 26, 2014 Author Report Share Posted September 26, 2014 Looks good, thank you for taking the time to help me out! The only thing about this design is that I will only be able to tune down to about 33hz without bending the port again. Will it be able to play pretty low with that kind of tuning? I would love to be able to play down into the 20's. How close can the internal port opening be to the top of the box? Also, where else would you suggest I add additional bracing? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.