2 subs, one box. sealed.

[94tegRS]

ok, I am building a new box, sealed this time for a couple alum12x's and am thinking each sub should have its own separate chamber right? or is it alright for them to be fighting each other for excursion?

[GScivic7]

nope, separate chambers will get you the best sound. Not hard anyways, just stick a piece of wood in the middle and screw the sucker down.

[94tegRS]

oh I know it aint hard, I just built a 6th order with plexi/neons and the sides have 2 seperate angles. I messed up though cuz right when I was gonna put in the divider I noticed my port would be too close to the sub so I had to move it back an inch which ruined the tuning I had figured, but oh well. and I am actually going to build a medium sealed box for one sub to se if its enough volume, cuz I have a full sheet still and I can get a single and a dual sealed out of it with the scrap I got, and rebuilding a box for an extra sub if necessary is cheaper than buying an extra unecessary sub right away.

[GSteg]

doesn't matter. As long as the internal volume is good, it'll sound the same.

[knorwj]

the subs need to be divided. if you put them together it will screw up all your calculations for tuning it and everything, much easier and it will sound better divided.

[GSteg]

There are no calculation for tuning with internal volume. Even in a ported box, tuning is independant of the number of subs.

As long as the internal box volume is correct, doesn't matter how it's put together. 1.2 cubes per sub with or without the divider isn't going to make any difference. Sound is the same.

[knorwj]

there are so many factors that will affect SQ for instance if the sub calls for a 12" 1.5" wide port and you makr it 13" long they will not sound as well as they shou8ld so believe me when i tell you to just throw the damn board in between the chambers.

A guy at work is an audio engineer. and somebodies kid came in one day who had done what you are thinkin by building one big box and put two subs in it, anyway it was built to exact specifications and it sounded like shit.. so he brought it to the guy in the audio department and he looked at it and that was the first thing he asked was whether he divided the chambers when the kid said no the guy told him that was the problem for various reasons that i will not go into... anyway long story short he divided it and it sounds perfect.


sooo anyway i think that that guy has a little more know how than you do gsteg, not being a dick or anything but quite honestly you just aren't old enough to have the experience or the education that this guy had. me saying that will probably piss you off to no end, but even if you are right how hard is it for this guy to just throw a divider in it? and not have to even worry who is right?

[GScivic7]

actually, I would take GSteg's word over a lot of other people's. I've been around these boards for a while, since PH.com, and he's helped me out a lot indirectly and knows what he's talking about. You want some real audio guru's. Head over to the audio forum on SHO.

[knorwj]

i'm not denying his word, I too have read many of his posts.

All I'm trying to say ( sincs after reading the full thread again and realizing it may not be clear). is that for the small price/work involved in adding a divider to the two chambers of his box, it would be far worth it to do so. Many people would say it doesn't matter, while many people ( including myself) would say that you need to divide them. Since I have never heard anybody say that a divided nox would hurt SQ/SPL I would say to just do it for the small price to pay.

[GSteg]

I meant to say there are no tuning freq. to be calculated when building a sealed box, which is exactly what 94tegRS is doing. Building a sealed box. Ported, Doesn't matter if the divider is there because port tuning depends on the internal volume, not the divider or how many subwoofers you have. I am not sure what you mean by the following:

"for instance if the sub calls for a 12" 1.5" wide port and you makr it 13" long they will not sound as well as they shou8ld"

Subwoofers do not call for anything. They are not picky. The user who listens to the subwoofers are picky. The tuning of the port only affects the requency response. You build the box accordingly to gain decibels where you want them to be at. There are no wrong or right way for a tuning frequency. It all depends on where you want to gain output at. Some people in their trucks likes to tune low, to gain output at the lower frequency since trucks have marginally less cabin gain than a car or an SUV. Since we're talking about port lengths also, its not always bad to go with a longer port. Longer power by an inch will do NOTHING, for a daily system. The tuning freq. that is changed is approximately 1hz or so. Of course depending how big the enclosure is already. Going with longer port will improve SQ because there are no peaks in the midbass region (can you say boominess?). Longer port equals lower tuning frequency, in terms less group delay and flatter frequency response with lower natural roll-off.

A buddy of mine is a speaker designer and then some guy on some forum had 2 12" subs that he wanted to put in a box. He asked if a divider is necessary, but my buddy said no because a divider does not affect sound quality as long as each sub has the same internal volume as without the divider. So the guy builds the box without the divider and says it sounds great.

But seriously, please do reason why a divider will help. I would love to hear the theory behind it. No one person can learn too much. If you can, that would be great because I can share the information with my fellow friends to tell them that they are wrong for not using a divider. It would be so wrong to use (3) 12" IDMAX in an infinite baffle install without a divider and getting a 10 out of 10 in the bass section at the IASCA finals (10/10 was the highest, no one else got a perfect 10). While I'm at it, might as well tell Richard clark that he shouldn't deserve to win the back to back IASCA finals in 1989-1990. I mean, why would anyone want to run 2 15" in an aperiodic box without a divider, for First place and worldwide recognition?? Pshh, I wouldn't.


Honestly, I laugh when people tell me about my age, experience, and education. No one over the internet is going to tell me what I know and what I don't know. Been many cases like this before, so I'm not surprised. Age means nothing. Take my two friend for examples. Nick (Team JBL) is only 18 years old. Damn him for beating many people with a mid 140db at 20hz in his class. While we're damning him, lets damn Dustin for getting 146.6db on a linearX mic with 2 12" (3000w RMS from his EQ amp). 146.6db may not sound impressive, but on a linearX mic in a truck with no cabin gain, it's enough to beat his closes rival by over 4db. Its equivalent to about 155db on an AC mic, which I call it the bragging rights mic, since it becomes inaccurate after 150db, at least for the ones before they have right now, which most people used. But who cares when you're holding the record in the NSPL of your class and you're only 16 years old? If age meant something, I would love to see what he'd get 10 years from now.

While we're at it, check out Loyd and his subs. Look at all the pretty trophies and records he holds. Only in his early 20's. Its funny how he used (4) 15" costing $130 each to win his class and holding record for a stock car with stock electrical system. So should his now daily driver (18) 8's be any good? Experience goes a long way doesn't it?

True the guy is older than me and has more "education" than I do (after all, I'm only a junior in HS), but how good is his education when it it runs up against Richard Clark's education who did not use dividers? Richard Clark has been designing, building, and doing so many things for companies around the world even before our parents met each other. When a guy designs DAC, invent the voltage stabilizer (capacitor you see from RF, LA, etc), owning over 5 patents , built the 60" subwoofer that did mid 160db at ~14hz, winning multiple IASCA championships, known as a world expert in his area, and not use a center divider, you know something being done right if he didn't use that divider.


I urge that installer to take a Double Blind ABX testing to hear the difference between a box with and without a divider. This will remove all physcoacoustics that is going on. Our minds are very power, making us believe in what we want to believe. Just like how some people say they can feel better acceleration in their car by just giving the car 91 octane opposed to the recommended 87 octane.

Even if a divider adds mental confidence, why take the time and add something that is not necessary?

But what do I know, stupid 16 years old don't know anything right? How could someone that associates with CEO's and chief engineer of buildhouses know anything? Point is, I can pull out so many equations and theory to prove my point, but what good does it do? Never going to change the fact that people look down at us younger guys, despite our knowledge. :o


-GSteg

[GSteg]

And if there are some misunderstandings, I apologize. My intention was not to put down anyone. I'm sure I sound like an a$s right now with my rambling.

[ccas]

I am a MECP certified installer, so I will offer my 2 cents on this. The divider did nothing other than the stabilize the enclosure more and take a small amount of air space away from the enclosure volume. To make an effective divider, it would have to be almost as thick as the car itself to actually separate the subs. 3/4 of an inch of wood is not keeping a 100+db frequency separate from the other side. If you turn a system up and can feel the bass outside the car....do you really expect a piece of wood to really keep that apart from the other side? If you really want to make your boxes sound better (sealed boxes specifically) use some polyfill to reduce your standing waves, but a divider will only reenforce your enclosure. If it was a weak box to begin with, then maybe it will improve your sound.

[CRX-Crooks]

You should have seperte chambers to keep the air from moving to much and have port tubes everything should me at company spec

[94tegRS]

actually I am going to build a ported box, 3.75 ft^3, slot ported to 23HZ, the -3db's barely above 20Hz. I built a sealed box on winisd, and the gain curve crosses the -3db line way up at 38Hz, and there is no size of box that can lower it. and I am assuming that that means it wont be loud at all at low frequencies. always have read large sealed boxes let the subs hit low but not with this sub I guess.

and wiht 2 I was going to give them 1.75 ft^3 each or 3.5 ft^3 total for both so the divider wouldnt have changed each subs airspace.

[CRX-Crooks]

seperate chamber to company specs