difference between using recommended enclosure specs and smaller or bigger?

[akuma4u]

hey.. im attempting to build a new enclosure for my u12 d2 sub and my custom zv3 12 with x spider and spl cone sub..

according to sundown, they both will be able to use the same enclosure which is great cuz i just need to build 1 single 12 ported box and not 2.

so sundown recommends using 2 cubes and tuning 32 to 35hz.. however,. i have been told 3 things

1) go bigger than 2 cubes like 2.15net to 2.20net as it will be louder and sound better

2) go smaller to 1.75 net and use a lot of port area and some say use 12-16sq in per cube,  exm 1.75net with 28sq inches of port tuned to 35hz

3) sundown recommends 16sq inches of port per cube but users here tell me to use up to 20-25 per cube which is obviously much more. they say using more port area will result in much more output due to lower port compression and lower velocity. however, others have told me to use 12 to 14 per cube as this will have better roll off and sound better on music.

 

so .. these 3 things have me confused,. i dont know whether to build a 1.75 and use a lot of port area or use 12-16per cube , or should i just build what they recommend which is 2net with 32 sq inches of port area , or should i go bigger?

 

what exactly will happen if i make the box smaller i.e 1.75 and use a lot of port area vs less port area vs a bigger box with more or less port area? etc

 

any help would be appreciated so i can build this box properly.

i am using 2000rms for my power.

[1point21gigawatts]

Around 2.3 cubes with about 37 sq” of port area tuned to 32hz. 4” wide port that yields a velocity slightly under 17 m/s. I had already told you this. Trust me dude. It’ll sound so good and loud. Or if you want more efficiency, then just incorporate a 6” flared aero port instead on the same 2.3 cubes net volume. The port area is about 9” less but the efficiency would make up for it. Less port area is needed when using aero ports. Think of it like this. What is used for optimal flow? What shape is a straw or pipe? 

[Backwoods]

A company gives recommended enclosure sizes/tunes that should work decently well in a wide variety of applications. They know not everyone has an SUV and some people are limited in space. But no single enclosure will work BEST in every vehicle. Different sizes, placements, and tuning is needed in different applications. There are people that have been testing different enclosures in a variety of vehicles for decades and they still dont always get exactly what they want on the first try. 

 

The enclosure that Mr. Gigawatt suggested would likely be great. Going larger is normally better if you have the room, as long as you are not using insane amounts of power. U series subs can handle way more than rated, your 2K wont hurt it in a 2.3 cubed box. There are lots of people running over double the RMS daily.

 

A recommendation, if you ask for help, and get it, but still dont trust the help you get anyway... Maybe you should just hire a professional that is experienced in building enclosures for sundown U series subs. There are a few with lots of great feedback from customers. Some also sell designs if you have the tools and experience to work with wood. 

[akuma4u]

Its not that im ignoring advice. The problem is 3 things:

1) i am limited space so the ideal optimal box wont be able to fit

 

2) i got several people telling me different things 1 guy says go up another says go down. For example, the port area issue. A few have told me to use a ton of port area. Then guys like the mod of this site i forgot his name but he has a bird in his display pic, and the dude that runs emf audio told me that a lot of port area is good for maximizing spl but bad for music and that 12 to 14 per cube is ideal as it will have better roll off. That guy told me he builds 2 cube 24 sq inch of port boxes for 1500 to 2500rms 12s all the time and it turns out great. Then the sundown tech dude on phone told me to use 1.75net with 28 sq inches of port tuned to 35hz...

So a lot of different guys telling me different things makes it confusing.

 

3) then my own research on the topic creates more confusion as i read peoples advice and its opposite of someone elses advice. Like this:

[akuma4u]

[akuma4u]

Those screenshots i posted is just am example of why i am confused cuz i read so many opposing views and advice... 

 

 

 

[Backwoods]

Because again, different vehicles, different setups, some are obviously competing and burping, some are playing music, lots of different subs being used, Some are ignorant and some just regurgitate what they've read online.

 

Dude from all of this I'd say if you're building your own box, just build what sundown told you to build. Otherwise pay a pro. Because it seems like no matter what you build, you're going to think it would of been better another way and look for someone to blame. And at least if you build what sundown told you to build, you can't blame us.

 

Everyone is not going to give you the same answers because everyone has had different builds and has had different results. The same guy saying he did better with a smaller box may do better with a bigger box in a different car. Or the same guy doing better with a big box with one sub may do better with a smaller box with another sub. And vice versa. The manufacturer recommended enclosure is a good starting point. Build that. Don't like it, try bigger, try smaller, try different port volumes and tunes... Keep all the boxes that weren't perfect.

 

Then once you get it perfect, get a new vehicle... And you're likely to see one of the previous "lesser" boxes do better in the new vehicle.

 

There's no one size fits all for all vehicles and subwoofers, or everyone would have the same exact setups and same exact enclosure. 

[1point21gigawatts]

When you gather information from all over the place and don’t use that information correctly to weigh right from wrong then it’s easy to become confused and indecisive about a matter. I skimmed through them screenshots and seen facts and fiction and didn’t even have to study it and keep reading it to asses the general knowledge from it. If I were a noob that didn’t know how to build enclosures, I could use that information you posted and come to a conclusion quick because I’m smart. If you do the mathematics on the port area of both enclosures I told you to choose from, one has 12.3 square inches of port area per cubic foot and the other has 16 square inches of port area per cubic foot. That’s kinda what was told to you in the screenshots you posted. And 2.3 cubes is 15% bigger than 2 cubes that’s recommended. That’s not enough of an increase to cause the subwoofer to reach its mechanical limits and bottom out and damage the subwoofer. That’s 5-10% less than the maximum increase before bottoming out would occur and the amp would have to be stronger to cause that on that subwoofer. You have understand each subwoofer is different and designing an enclosure has to be done by factoring in the t/s parameters. The recommendations of sizing is just a basic idea. And when it comes to port noise, the more the rms and lower the tuning, the wider the port has to be to not have port noise. More rms increase port velocity and lower tuning increases port velocity. Some designers and builders use less port area to accommodate for the area available when building an enclosure with a lot of subwoofers and it helps with bandwidth and accuracy depending on the application and design, but takes away from the output. As long as it isn’t a crazy amount of port area, the bandwidth would be fine and it wouldn’t reach mechanical limits. That why I suggested an spl slot port enclosure with 16 sq” per cube and a musical aero port enclosure with a little less than 12.3 sq” per cube. And a 15% increase would increase output without reaching mechanical limits. Most pros that compete increase the sizing of their enclosures by 10-20% to increase output and they throw more than rated rms at the subwoofers. Plus recommendations about sizing is just to reference. You have to factor in the t/s parameters of the subwoofer and the rms of the amp. That amp 2400.1 you are using isn’t doing 2000 rms after rise. Rise differs on each frequency, subwoofer and application and cabin area surrounding said enclosure. Dude just messaged me earlier today and he is rising from 1 ohm to about 4 or 5 ohms and on a bass 30k only doing 9000 rms. So a 30,000 rms amp is only doing 9,000 rms after rise on his set up on whatever frequency he tested it on with an amm-1. So with that said, the enclosure has to be bigger because you are probably doing around 1000 rms. That figure is based off of the specs of that amp and the absolute lowest rise if the subwoofer, application and cabin area surrounding it permits minimal rise from about 1 ohm to 2.5 ohms. Rising from 1 ohm to 2.5 ohms is minimal rise and would make any bass head happy as shit. Before I begin to type or draw something up, I learn every piece of the equation and factor in so many different variables and calculations and base the variables off of facts and if facts are unavailable and it’s something like impedance rise, I would factor in the best possible scenario when it comes to that when designing an enclosure because if I calculated using the worse case scenario of impedance rise then it would leave too much room for error. Factoring the best case senecio leave no room for error when it comes to that variable. Then on some variables I have to factor it worse case scenario to ensure no errors arise. Averaging is something that works with some things but averaging can be problematic if something in the equation is below average or below average.

[akuma4u]

49 minutes ago, Backwoods said:

Because again, different vehicles, different setups, some are obviously competing and burping, some are playing music, lots of different subs being used, Some are ignorant and some just regurgitate what they've read online.

 

Dude from all of this I'd say if you're building your own box, just build what sundown told you to build. Otherwise pay a pro. Because it seems like no matter what you build, you're going to think it would of been better another way and look for someone to blame. And at least if you build what sundown told you to build, you can't blame us.

 

Everyone is not going to give you the same answers because everyone has had different builds and has had different results. The same guy saying he did better with a smaller box may do better with a bigger box in a different car. Or the same guy doing better with a big box with one sub may do better with a smaller box with another sub. And vice versa. The manufacturer recommended enclosure is a good starting point. Build that. Don't like it, try bigger, try smaller, try different port volumes and tunes... Keep all the boxes that weren't perfect.

 

Then once you get it perfect, get a new vehicle... And you're likely to see one of the previous "lesser" boxes do better in the new vehicle.

 

There's no one size fits all for all vehicles and subwoofers, or everyone would have the same exact setups and same exact enclosure. 

im not looking to blame anyone. help is appreciated no matter what.

what i find is that people just have different opinions on enclosures and what works. port area is a big area where there are opposing opinions.

yes, i can build several boxes and test and this is what i will probably end up doing. will be costly but i guess i have no choice.

as for now,. i am trying to build the box 1point21gigawatts told me to , but since i am limited in space, the closest i could come up with is the following. mind you my max dimensions are 13.5 tall x 32 wide x 17 deep , i had to push it .25 in the width and .5 in the depth to get more airspace.. i will have to router the outer edges to slide this thing in .. it will be TIGHT.

maybe 1point21 can take a look and tell me what he thinks.. this is the BEST i can do with the space i have...

[1point21gigawatts]

Read this. People believe things when they hear it from reputable sources. 

 

https://ddaudio.com/subwoofer-enclosure-design-bending-the-rules-maximize-output/