RooTxBeeR Posted May 7, 2017 Report Share Posted May 7, 2017 So I recently built a box for my 2 X-18's. It was a really rush build to just have something since I blew my old subs and something to just break them in. This is the first time building such a large port in a box, last several boxes all used aero's too. But with all of that, when it came to the port, there was a huge difference in width from the center of the bend and the actual width. I made a 45 to compensate the difference but it still made me curious. I know having a point through the port where the width is smaller than the planned width will choke it. If there is a portion however that is larger, how would that effect playback? Here are some pics to explain what I am talking about. This is the width of the port by plan and on paper. This is the width of the bend 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...
caraudionoob Posted May 7, 2017 Report Share Posted May 7, 2017 Basically, you're asking if having 45's will do anything. This has been debated over and over again. Here are some of the threads that cover it. Link to comment Share on other sites More sharing options...
RooTxBeeR Posted May 7, 2017 Author Report Share Posted May 7, 2017 1 minute ago, caraudionoob said: Basically, you're asking if having 45's will do anything. This has been debated over and over again. Here are some of the threads that cover it No I am not asking if 45's will do anything. I stated, "If there is a portion however that is larger, how would that effect playback?". I know having a portion of the port that is thinner will choke the port, but how will the inverse effect playpack, port noise, and other aspects of playback. 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...
ShadeTreeMechanic Posted May 7, 2017 Report Share Posted May 7, 2017 As far as air flow would go, a decrease in cross section would cause the velocity to increase. An increase in cross section would cause the velocity to decrease. As far as sound waves go, I think it would effect the overall average size of the port. I have always wondered if having a tapered port where the cross section increases like a horn would help output. Edit: further thinking about port velocity, a smaller section would choke the port because it would increase velocity at that point. A larger cross section would decrease velocity and lower velocity is not detrimental to port effeciency. 91 C350 Centurion conversion ( Four Door One Ton Bronco) 250A Alternator (Second Alternator Coming Soon) G65 AGM Up Front / Two G31 AGM in Back Pioneer 80PRS CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon) Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon) Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 7, 2017 Report Share Posted May 7, 2017 I suspect the increase in port internal volume will lower the tuning frequency slightly due to a greater mass of air being inside the port. I've never tested to see how much difference it makes but I bet its pretty small, definitely not something to worry about. "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...
RooTxBeeR Posted May 9, 2017 Author Report Share Posted May 9, 2017 That is what I was looking for. Thanks guys. Half of me wanted to just go buy a design from someone reputable, the other half wanted to build 25 boxes, all being nearly identical just 1 variable difference to test for myself what does what and come to a final design myself. 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...
the_garynator Posted May 9, 2017 Report Share Posted May 9, 2017 It shouldn't effect it. A port with varying dimensions will function as the if it were the same throughout using the smallest opening. I.e. if your port has a section that is 15x5 and a section that is 15x8, it will function as if it were 15x5 the whole length. Changes in size may cause it to be slightly less efficient, or more efficient (i.e. a port that starts small and gets larger at a certain rate can make for a more efficient acoustic coupling.) In your case it shouldn't make a noticeable difference and as far as tuning, it should act the same as if the wider section was the same as the rest. Current Build: Project Flexington: 157.6db @ 37hz Parallel 6th order walk through, DC Neo Elite 18s, 4 DC 5.0ks, JY Lithium, 12 banks of XS Caps Old Builds:150db and HAIRTRICKs from 2x 12" Power Acoustik Mofos (6th order blow through) ;<p>Roadmaster Wagon Build - DC LVL 6 M3, Kicker Warhorse ; Godzilla swapped 240sx ; 6th Order Bandpass Alpine Type R 12 ; Fully loaded DC Level 5 18" 240sx Link to comment Share on other sites More sharing options...
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