Motor Strength vs Port Area

[shizzzon 10+ year member]

with 4 15s, which i've done before, i could use 140sqin of port.. terrible wall... that was my first one. Luckily i still did over a 153 with it though.

My car is small, very small.

So small.. i can only stack 2 12s on top of each other. Anything bigger than a 12, the subs have to be staggered.

 

[skmfkr 5,000+ posts]

oh ok i see what your saying. yeh i think im with robin with the 6 12s idea but i think me and him are thinking more of a middleweight bass boxing build than a burp car.

 

[shizzzon 10+ year member]

oh ok now we are on the same page.

I'm not looking for sustained pressure levels, just burps.

I do park n boom which is like bassboxing except they meter you outside the car for 30second average.

Of course, that needs to be sustained but because it's based on a fuse limit, i will never heat the coils up in time so that's not as important to me.

I dont need that part of competition to get me to finals. Just burping.

 

[cthedinger 10+ year member]

What about 6 xl 10s? that way you could use all your amps and still have plenty room for port

 

[shizzzon 10+ year member]

WAY too much power.

I want to run 4 @0.4 ohm and i'm limited by 340A of fusing in this class.

 

[ContourSPL 10+ year member]

Hey Sean. This is Chris with the Jeep. What are you going to do about your sunroof? I think your car itself is going to be a huge limiting factor. Best of luck to you.

 

[shizzzon 10+ year member]

no cuz my car hates glass-bracing plus i will experiment

with sealing sunroof from inside anyway

i can do 157s in the kick now i just gotta load elsewhere

 

[T3mpest 10+ year member]

Since your burping I'd do the 12's. You get the most port area that way. Ultimately, the reason walls do so well at least partially and why cone area isn't as important is because when your playing near tuning a wall gives you alot of room for airspace which leads to a effecient alignment in terms of getting the cones to move. Also, you have a very large port area that ends up moving far more air than the woofers themselves near tuning. Bigger ports compress less so your getting a better chance at higher numbers. Also, I would assume 4 12's needs less airspace than 3 15's, so again all things equal your going to be more effecient this way, especially if your realy only concerned about a burp on one tone.

 

[Annnarbor84 5,000+ posts]

I know cone area really doesnt mean much for walls. I've only had 2 walls and am about to tear it down and build another to try and break 160db.. hopefully.
I have over 30kw on tap to be able to use so power isn't a problem.

I'm looking at sub choice. I am part of Team DC Audio and have gotten some ideas from other competitors but they don't know the port area i can work with with different sub choices.

Since i have no longterm knowledge of walls, i ask those that do and see what others think.

Out of 16-18cuft NET possibly-

2 18" Lvl5s @26kw = 450sqin of port (146lb of motor)

3 15" Lvl4XLs @19.5kw= 500sqin of port (150lb of motor) - recommended by Rusty @DC

4 12" Lvl4XLs @26kw = 650sqin of port (200lb of motor) - recommended by the A-Team

5 12" Lvl4XLs @32.5kw = 500sqin of port (250lb of motor)

Before anyone say it, rusty said anything less than 10kw per sub, i need to run Lvl4XLs in the lanes. If i try to run 3 Lvl5 15s... it's too much power on tap (39kw) and i'll blow fusing since i'm in a fused class.. So i have those options above.

Many competitors have told me cone area is not needed when using a wall. I have seen this in person proven plenty of times!

What i have noticed for walls is i need LARGE internal volume and LARGE port.. tuned correctly of course.

But what i've experienced too is it helps to have plenty of motor and plenty of coil to dissipate heat loss. ( i also do 30sec averages too.)

Rusty told me 3 15" XLs would be better than 2 18" Lvl5s because they are actually more efficient and have more coils to dissipate heat.

However... the A-Team thinks i should go with more motor and suggests i go with 4 12XLs since it gives more motor and more port area... but the least efficient...

I know efficiency comes from cone area which i shouldnt be lookin at so basically... i'm lookin for reassurance, hehe, that 4 or 5 12" XLs is the way to go....

Whoever told you cone area is not needed, are off their fucking rockers...... That is complete bullshit, you need the get the most cone area and motor strength you can. A Team does great numbers and has a ton of experience with DC, I would take advise from someone who is actually loud, imo........

 

[shizzzon 10+ year member]

The A team told me that so i guess i should listen and not listen to them at the same time...

I've witnessed low cone area do high numbers so i understand what the were suggesting me.

I've seen a 160 out of 2 18s and only 2 1500ds

and heard about 2 15s doin a 160 off of 4 4000ds.

 

[basebalz13 10+ year member]

The A team told me that so i guess i should listen and not listen to them at the same time...
I've witnessed low cone area do high numbers so i understand what the were suggesting me.

I've seen a 160 out of 2 18s and only 2 1500ds

and heard about 2 15s doin a 160 off of 4 4000ds.

You should also know Bola Adenkule, He does a 160+ at the head rest with just 2 18's.

your limited to 340 amps of fusing, and working with a wall. I take it your going into Modified 4? Bola's class //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.

 

[Stalin-ohaulic]

i like the A-team recommendation too. I'm wondering though, how many cubes per sub are you factoring in and what impedence are you wiring to? Obviously I'm curious about your impedence rise. Also, I understand the premise of the question, but getting the port to act as a radiator is dependant on the motor strength so it's difficult to compare 1 vs the other when they are in a symbiotic relationship. I think a more appropriate question is "Power vs Enclosure Efficiency" and the answer is, which do you have more of, power or volume? Clearly you have more power than volume so build a small enclosure with as much port area as possible to minimize impedence rise while maximizing efficiency. Just my humble opinion.

 

[shizzzon 10+ year member]

bola is in m5 this year.

from what ive played with, they want the

largest volume possible.

i figure 3-4 cubes per 12 and if thats too

much, i can always displace space.

 

[slam 5,000+ posts]

More cone are will not necessarily get u louder. This is science and how u use space will determine what shows on the meter. first thing Id ask is what vehicle is this going in... this should tell u how many subs u need

 

[shizzzon 10+ year member]

exactly slam, that's what i've been told too.

It's going in a scion tc.

I've played with a couple walls physically and some cad designs so i know what can fit in there on a flat baffle.

4 15s is impossible efficiently.

I'm currently running 3 15s but i can get more motor and port area with 5 12s.

I can also run just 2 18s but 4-5 12s seems to be the best bet, in my opinion.

I can still get just as much port with 2 18s as i can with 4-5 12s.