classic100% Posted August 12, 2013 Report Share Posted August 12, 2013 Just got a new enclosure design for 2 12 AB subs, the port is 3.5 inches wide. I showed a friend the design and he is said the port should be wider. What is the concept behind port size? Bigger louder? Smaller cleaner sound? Is it a calculation? Or is it just based on personal preference? Link to comment Share on other sites More sharing options...
RooTxBeeR Posted August 12, 2013 Report Share Posted August 12, 2013 Depending on the type of port, ie. Slot port, aero port. Lower amounts of port allow for wider frequency range and less output. While more port allows for the opposite. 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...
Sergeant_Skyrim Posted August 12, 2013 Report Share Posted August 12, 2013 Depending on the type of port, ie. Slot port, aero port. Lower amounts of port allow for wider frequency range and less output. While more port allows for the opposite. I've heard this same exact thing also. I'm interested in doing some testing with my setup because I've got a removable port for my 2 12 inch Zcons. I think the port is normally 5 in wide x 13 high but with the removable is 3.5 x 11.5. With removable in I can play down to ~25/26, without it 28, and on the ear-o-meter the higher notes sound exactly the same and I can play just as high with either setup. If the next meet I go to has a meter I really want to see what the difference is with my removable port in vs. out other than the inability to play as low Build in progress Link to comment Share on other sites More sharing options...
SnowDrifter Posted August 12, 2013 Report Share Posted August 12, 2013 Port area is based on power, tuning, cone area. And as for low port area having a wider bandwidth: I disagree You will here a lot of people refer to port area per cubic foot of box space . This is a very general rule of thumb, so don't take it as gospel. Lots of boxes will be above or below that 12-16sqin/cuft of box space. My next box is 23sqin/foot LOL. I've had a box that was 7sqin/foot, 14 per foot, 18 per foot. They all sounded great ~~~~~~~~SAY NO TO PHOTOBUCKET~~~~~~~~ Snow's DD-1 tracks here: https://www.stevemeadedesigns.com/board/topic/167433-snows-dd-1-tracks/ My take on OFC vs CCA: https://www.stevemeadedesigns.com/board/topic/110381-things-that-piss-you-off-in-the-car-audio-world/?do=findComment&comment=2461444 Link to comment Share on other sites More sharing options...
Krakin Posted August 12, 2013 Report Share Posted August 12, 2013 Gonna leave this here. Guy lead e in the right direction on this topic. A couple of quick highlights: Port area is NOT based on box volume. It is based on driver Sd and Xmax along with tuning frequency. The same driver in 4 cuft or 6 cuft needs the same amount of port area. A driver with high Xmax needs more port area in 4 cuft than a driver with low Xmax in 4 cuft. "Bandwidth" is NOT based on port size (this statement is crazy if you know anything about how a port works). Only way the port area would affect bandwidth is if the port is small enough that it does not operate correctly. Also left "the loudspeaker design cookbook" as a great source to learn more. 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...
RooTxBeeR Posted August 12, 2013 Report Share Posted August 12, 2013 Gonna leave this here. Guy lead e in the right direction on this topic. A couple of quick highlights: Port area is NOT based on box volume. It is based on driver Sd and Xmax along with tuning frequency. The same driver in 4 cuft or 6 cuft needs the same amount of port area. A driver with high Xmax needs more port area in 4 cuft than a driver with low Xmax in 4 cuft. "Bandwidth" is NOT based on port size (this statement is crazy if you know anything about how a port works). Only way the port area would affect bandwidth is if the port is small enough that it does not operate correctly. Also left "the loudspeaker design cookbook" as a great source to learn more. where did you get that quoted info from, would like to see it elaborated a little more. Maybe even with equations 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...
TeamHT Posted August 12, 2013 Report Share Posted August 12, 2013 I disagree a little bit with the bandwidth notion in relation to port size. Maybe to say a wider bandwidth is a little general, but in all of my spl testing the more port I used the peakier the box became with steep rolloff. When I would go smaller the response was a lot more flat. Tell me...does this smell like chloroform to you? Link to comment Share on other sites More sharing options...
classic100% Posted August 12, 2013 Author Report Share Posted August 12, 2013 Port area is based on power, tuning, cone area. And as for low port area having a wider bandwidth: I disagree You will here a lot of people refer to port area per cubic foot of box space . This is a very general rule of thumb, so don't take it as gospel. Lots of boxes will be above or below that 12-16sqin/cuft of box space. My next box is 23sqin/foot LOL. I've had a box that was 7sqin/foot, 14 per foot, 18 per foot. They all sounded great Is there a formula with the power, tuning and cone area numbers that is use to determine port size? Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted August 12, 2013 Report Share Posted August 12, 2013 Port area is based on power, tuning, cone area. And as for low port area having a wider bandwidth: I disagree You will here a lot of people refer to port area per cubic foot of box space . This is a very general rule of thumb, so don't take it as gospel. Lots of boxes will be above or below that 12-16sqin/cuft of box space. My next box is 23sqin/foot LOL. I've had a box that was 7sqin/foot, 14 per foot, 18 per foot. They all sounded great Is there a formula with the power, tuning and cone area numbers that is use to determine port size? not really, it comes down to experience for the most of it. That is why some of the best sounding/loudest vehicles didnt happen on 1 box design, you are talking months to years of testing, box design changes, port size changes, etc. I have had a boxes with 6.8 sqin of port play well from 20hz-65hz and do it flat and pretty damn loud, also had a box with 16sqin of port tuned to 40hz crush the mid 20s like no ones business. Honestly there is a ton i dont know, and had no clue why those boxes came out so well when going in i knew they were going to sound weird but didnt. Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
bkolfo4 Posted August 12, 2013 Report Share Posted August 12, 2013 I have said it many times - the reason you are getting "flatter" response from your smaller ports is because they are small enough that they do not operate as they should at high volumes. . . A port operating as it should will cause the system to roll off very quickly below tuning frequency. So if you are tuned at 35 and the port is operating correctly, output will drop quickly below 35. If the port is small, the roll off will change and you might have more low end due to port compression. I personally would not make a statement "less port area has more bandwidth". I would say "if you want lower frequency response, tune lower, but always use the correct amount of port area when possible". Current system: 1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s Previous systems: 2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz. 1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz. Link to comment Share on other sites More sharing options...
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