RooTxBeeR Posted April 27, 2015 Report Share Posted April 27, 2015 To properly tune a 4th order, you need to tune the ported section to the sealed resonance of the sealed section. After that, it's all about port area. On 11/20/2012 at 8:54 PM, AMI CUSTOMS said: Turned mine up today at a light, guy next to me his steering wheel started moving and he looked over at me like I was a magician lol. On 5/9/2012 at 8:45 PM, skittlesRgood said: fuck the plating. look at what the main metal used is. you could buy unicorn blood plated terminals but if its just covering up dog shit, whats the point On 4/10/2013 at 12:26 PM, mrd6 said: I'll admit, half way through sanding that fiberglass in the rain and cold while I was all itchy I was definitely starting to question why i was doing this haha Soon To Be '04 Ford Escape US Alternator 280A Hairpin D4800 Under the Hood (6) XP3000's in Rear 1/0 SHCA & XS Power 4 runs to back TORK2 kit from Tony @ CE Auto Supply Pioneer DEH-80PRS DD AW6.5 (2) per door *Tweeter Unkown* DD SS4a & C3d (2) SCV4000 @ .5Ohm (2) 15" Sundown Zv5 Link to comment Share on other sites More sharing options...
757lmj Posted April 27, 2015 Author Report Share Posted April 27, 2015 To properly tune a 4th order, you need to tune the ported section to the sealed resonance of the sealed section. After that, it's all about port area. How does that get done?? Is it just the peak of what it plays sealed? Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted April 27, 2015 Report Share Posted April 27, 2015 To properly tune a 4th order, you need to tune the ported section to the sealed resonance of the sealed section. After that, it's all about port area.How does that get done?? Is it just the peak of what it plays sealed? The sealed section of the box changes the resonant frequency of the sub. The larger you make the sealed side, the lower it goes. For example, if your sealed side is 4.5 cubes, the resonant frequency should be about 44.7 Hz, you can get this info out of WinISD. The purpose of the "rule" about tuning the front chamber to the resonant frequency of the rear chamber is so you can get a flat response curve. But this is not in-vehicle flat response that I'm referring to, this would be if the sub was measured sitting out in the middle of an open area where there is no cabin/room gain. Because we are not trying to achieve that kind of flat response, the rule does not apply in this situation IMHO. My question for RooTxBeeR is, what do you think the consequence is of NOT tuning the front chamber to the resonant frequency of the sealed side? "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...
757lmj Posted April 27, 2015 Author Report Share Posted April 27, 2015 How many sq inches of port per cubic foot of volume in the ported side??? Should I stay around 15 or 16 or does a bandpass take higher bc of the tuning? Explain difference of sq in of port to volume in bandpass and regular ported box if there's any difference. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted April 27, 2015 Report Share Posted April 27, 2015 Port area per cube rules are kinda like arbitrary band pass box ratios, they are over simplifications. There are better ways to calculate how much port area you need. The important thing with port area is you want to keep port velocity low enough that it doesn't make port noise or cause port compression. This is the same for ported boxes and band pass boxes. With band pass boxes its extra important since all of your sound energy is coming out that port. It usally easier with bandpass boxes too since they have higher tuning which makes it easier to get a large enough port in the box without it being a mile long. For your situation I'd shoot for 130-150 sq in or port area. At 150 sq in the port will only need to be 10-1/8" long, so it shouldn't be too tough to fit. This is assuming 9 cubes of airspace and a 47 hz tuning. "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...
757lmj Posted April 27, 2015 Author Report Share Posted April 27, 2015 Also my square port comes about 2 inches from the back of my subs... square in the middle, triangle of subs, port in middle right behind magnets. is this ok?? It's 30×30×17.25 in the ported section Link to comment Share on other sites More sharing options...
757lmj Posted April 27, 2015 Author Report Share Posted April 27, 2015 For your situation I'd shoot for 130-150 sq in or port area. At 150 sq in the port will only need to be 10-1/8" long, so it shouldn't be too tough to fit. This is assuming 9 cubes of airspace and a 47 hz tuning. Right now I'm at 138" and 144" 11.75 and 12" square. 11.75" square needing 9 inches of port and 12" square needing 9.5 inches of port. Both 47 hz. Will the port being only a couple inches from the back of my subs matter? Link to comment Share on other sites More sharing options...
757lmj Posted April 27, 2015 Author Report Share Posted April 27, 2015 Sub mounting depth is slightly over 7" Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted April 27, 2015 Report Share Posted April 27, 2015 Also my square port comes about 2 inches from the back of my subs... square in the middle, triangle of subs, port in middle right behind magnets. is this ok?? It's 30×30×17.25 in the ported section It's hard to say for sure without seeing what it would look like. Can you draw a picture? It definitely doesn't sound ideal though. I'd probably consider adjusting the layout of your box. Also I'd suggest taking Joex's advice and make the port removable or otherwise adjustable. Port tunings don't always come out exactly where you want them to. "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...
hoit Posted April 27, 2015 Report Share Posted April 27, 2015 I could pick your brain for days Triticum! Can't wait to shake your hand and look you in the eye! The more I learn, the more I realize I don't know. I am still very curious on how you get all your info. We'll see each other soon enough! 757lmj, if you can get a pic of your current set up...I'm sure these professionals can lead you in the right direction! 2007 Chevy Aveo Ls sedan 2 Sundown Xv2 on scv4k @ .5 ohm 2 pair RE XXX 6.5 components on sax200.4 @ 2 ohm Big Three, Three runs 1/0 power from front to back, 1 ground front to back Two runs ground from rear bank to chassis XS power d3100 upfront, 3 Odyssey 2150s in bank Singer 220 amp alt Link to comment Share on other sites More sharing options...
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