no dont listen to him. if your going for daily with a little more output, you could go 35-38hz with 15-17 per and you should be fine. that should give you a good star off point. then you can redo the box to your liking. also you should figure out what freq your car likes, or simply do 2 boxes. 1 daily, 1 comp.

Making that recommendation doesn't tell him the exact minimum amount of port area needed to avoid port noise.

so you are telling me that he will have port noise with 15-17 per and it will be audible???? are you a dumbass, or just a dumbass.

my recommendation is not telling him the minimum amount or port area needed without port noise, its giving him a proper starting point for a daily system with lots of output.

While it will reduce port noise your recommendation will make mechanical failure more likely. My estimation gives the OP the minimum amount of port area needed to reduce the likelihood of port noise as well as reduce the chances of mechanical failure.

You recommending 15-17 proves your stupidity and your lack of understanding of enclosure design. Stop making recommendations as all of them have been proven incorrect.

get real dumbass, no one is going to use 29sq inches per for a daily system. what a retard. stop making like you know. and when were my recommendations proven wrong? or are you talking outta your ass.

jacob said Approx 25mm linear each way. he also said 64 in squared should do it.

yeah brandon daily whatever you do, do not listen to durans dumbass

PORT DESIGN FORMULAs for SUB WOOFER ENCLOSUREs

Guide: Using WinISD

Two fun little tidbits of info for those that like to get all technical

Stealth, stop cluttering Brandon's thread with name calling. If you would like to point fingers and insult me do it in a private message.

Brandon, use Jacobs recommendations as it is always best to listen to the manufacturer.

no i think it would be better to listen to duran, 29sq inches of port per cube sounds spot on for a DAILY SYSTEM.

no i think it would be better to listen to duran, 29sq inches of port per cube sounds spot on for a DAILY SYSTEM.

How many times do I have to say this? Apparently the "All-knowing Stealth" can't wrap his head around this, you design the enclosure around the subwoofer, not the other way around. Enclosure size does not dictate port area, the parameters of the driver does.

um no i think you build the box then pick the sub... lol no shit.

all in all, brandon daily go with his idea and sue his ass for the cost of the wood you wasted. lol use winisd and see.

Its just a port thread. Calm down dude.

no, its not just a port thread. maybe to you. its about helping an SSA member when he needs it.

no, its not just a port thread. maybe to you. its about helping an SSA member when he needs it.

Stealth, I hope your home is enveloped by a volcano, you have proven time, and time again that your insight is generally false. Instead of flaming someone you need to be able to express why you think something over someone else belief.

no, its not just a port thread. maybe to you. its about helping an SSA member when he needs it.

Stealth, I hope your home is enveloped by a volcano, you have proven time, and time again that your insight is generally false. Instead of flaming someone you need to be able to express why you think something over someone else belief.

should i get the exact xmax or should i just go with 145sq in? bc i can email jacob about it...lol he probably hates me with all the emails i send him.

At least he responds to you.

hey bro give him time, he gets alot of emails every day, hell he gets like 3 from me damn near every day lol, what do u need help with? maybe somebody on here can help ya.

and stealth there is no need to get all bent out of shape about this topic, everybody has their opinions about how much port area to run, there is no right or wrong answer, from what i've been reading. its all about user preference

jacob said Approx 25mm linear each way. he also said 64 in squared should do it.

That will work, but sounds like it is on the small side. . .

Funny how all of this calculating port size based on enclosure volume has become the "law". . .

Enclosure size is NOT used to correctly calculate the required port area. Sorry. I wish people would stop making this assumption. Why did someone even calculate Duran's calculation to be 29 sqin per cube?? It means nothing. . .

There are also more issues with port area than just port noise. The port will not work properly if there is too much compression. In a car I doubt you would ever notice it as long as you have a subsonic filter (at enough compression, the box looks like a leaky sealed box), since it is normally so loud it becomes less noticable.

And what is wrong with designing a "daily" box correctly? What is your definition of "daily"?? Maybe you think SPL boxes need more port area? Ever think maybe that is so the port operates correctly??? Tuning frequency should be the only difference between "daily" and "SPL" if you want the box to actually operate as it is designed. . .

I will admit, I know you can get away with less port area in a car system. . .I help people design boxes all the time with less than perfect port area when space is tight. It works, but don't jump on someone's response when they give what is actually the correct answer and then use false info to try to prove it wrong. . .

^this. thanx for clearing that up. would u suggest the same amount as duran?

If he does you are going to need a different car. Lol. All about compromise.

For an 18 like that, I would try for at least 80. . .100 if you can.

Brian

Thanks for the support Brian

I hate the port area rule of thumb. It's just a way for people to try to skip the math, and it doesn't work.

Thanks for the support Brian

I hate the port area rule of thumb. It's just a way for people to try to skip the math, and it doesn't work.

I was the one who did the calculations that it is 29in^2 per port area, just to see its relationship compared to the "general rule of thumb" which we were supposed to go by. I feel as though companies like Fi shouldnt put that on there website (even if it is a starting point) then others get bashed for something they thought was right from start including me (that is misleading the consumer). Instead for each driver put how much port area is required and stop steering the consumer in the wrong place. Id rather they give the formula so I can do the math then be bashed for information I thought was to be followed since the MANUFACTURER said to follow it. It is to many he say or she say rules in car audio and healthy debates like these help weave out all the bs.

I appreciate Duran for passing the formula on and will be using from here on it then the in^2/cube rule we see on a daily basis.

If he does you are going to need a different car. Lol. All about compromise.

lol my backseat is already out, so i dont mind having that much port, i just want whats going to work best.

Thanks for the support Brian

I hate the port area rule of thumb. It's just a way for people to try to skip the math, and it doesn't work.

I was the one who did the calculations that it is 29in^2 per port area, just to see its relationship compared to the "general rule of thumb" which we were supposed to go by. I feel as though companies like Fi shouldnt put that on there website (even if it is a starting point) then others get bashed for something they thought was right from start including me (that is misleading the consumer). Instead for each driver put how much port area is required and stop steering the consumer in the wrong place. Id rather they give the formula so I can do the math then be bashed for information I thought was to be followed since the MANUFACTURER said to follow it. It is to many he say or she say rules in car audio and healthy debates like these help weave out all the bs.

I appreciate Duran for passing the formula on and will be using from here on it then the in^2/cube rule we see on a daily basis.

I was not bashing anyone. I honestly did not look to see who posted it. Just making a point, since this thread turned into bashing the only person who really knew what they were talking about.

Those guide lines work, they just are not hard rules.

Learn as you go man. No harm done.

Not a problem I appreciate your response and the way you handle it. So to get this clear if you want the best port area for you subwoofer then plug your figures into the formula and use what you get, right? The only time the general rule of thumb (in^2/cube) can be used is for: not enough space in an install/enclosure to give the driver its recommended port area due to driver specs, if you dont want to take some time to do some math or just to make a quick box? One last question, when people do drop in's with two different drivers and say one out performed the other then it is not a fair test since the box is not built to the specs of each driver unless that is the box you are using in your install?

Thanks for the input and I dont mind learning, that is why I ask question or make the comments I do to spin the wheel in people's minds.

I take each box I design on a case by case basis. The estimates work good. I have used less, and I have used more. If you tune at 32 hz and then you play a lot of music at 32 hz, you may hear a little port noise. Depends on the amount of air the driver can sweep and how hard you are driving it. Normally in a car things are getting really loud by the time you really start compressing the port and it is not audible. The ranges suggested perform good vs the amount of volume required for the port. Large ports get really long in small boxes!

At the tuning frequency, sound is radiated from the port. If you want the port to operate 100% correctly with no compression or noise, use the formula.

Brian

I take each box I design on a case by case basis. The estimates work good. I have used less, and I have used more. If you tune at 32 hz and then you play a lot of music at 32 hz, you may hear a little port noise. Depends on the amount of air the driver can sweep and how hard you are driving it. Normally in a car things are getting really loud by the time you really start compressing the port and it is not audible. The ranges suggested perform good vs the amount of volume required for the port. Large ports get really long in small boxes!

At the tuning frequency, sound is radiated from the port. If you want the port to operate 100% correctly with no compression or noise, use the formula.

Brian

Nice way to sum it up in 1 answer, exactly what I wanted to know. Thanks again Brian .