LOL. Im gonan build this maybe. :shock:

[nutxo]

I was trying to figure out how to get my internal ports as far away from the subs as possible while keeping the distance between both subs and ports the same. Not an easy task in such a small box. I came up with this. I put the ports in the opposite chambers. Any thoughts?

[ttocs]

my thought: a sealed box would be 10x easier and could have been put together already

[wash with gasoline]

Looks like a good use of space to me.
When you have the ports that close to a wall of the box it will change the tunning a little because the port will act like it is longer

[soundbit]

AAAhh the joys of effective tuning length

[stipud]

Seems like slot ports would be easier to me, but it's a neat idea.

[jbob0124]

It looks cool, good luck with the build, I will have to agree with ttocs though

What program is that?

[Eric D]

I assume you plan to use elbows on the tubes, not those 45 deg mitered corners, as they would create some awful turbulence noises.

[holmis]

What program is that?

i think its SketchUp ; this one:

http://en.wikipedia.org/wiki/SketchUp

[jbob0124]

What program is that?

i think its SketchUp ; this one:

http://en.wikipedia.org/wiki/SketchUp

Cool, thanks. Think I may give it a shot.

[nutxo]

I assume you plan to use elbows on the tubes, not those 45 deg mitered corners, as they would create some awful turbulence noises.

I havent figured out how to make elbows yet. Oh and yeh. Its google sketchup.

[zeropoint0.5]

Seems like slot ports would be easier to me, but it's a neat idea.

i would do this also, recalculate the round port into a slot port !!! Stay with the same length,

just make the enclosure that bigger that the thickness of the wood is calculate in it....

you're idea is more, why do easy when we can do it difficult......

[audiophyle_247]

Ported is ALWAYS worth the added effort, sealed just doesn't hold a candle to the performance of a good ported design.

Seems like an aweful lot of added complexity for a little added benefit. I bet you could replicate the port snaking with a slot port much easier. Once you throw in 45* elbows your port lengths are going to shrink, and take up more airspace.

Maybe build two slot ports half the height of the box and stack them together like you have these, each a mirror of the other but both centered on the box face. That make any sense? Lol

[ttocs]

could not disagree more myself. I have found that with a good solid sealed box, as well as signal manipulation(bass cube for example) that you can get just as much sound, just as clear and still have the ability to tune it on the fly as well.

[Eric D]

could not disagree more myself. I have found that with a good solid sealed box, as well as signal manipulation(bass cube for example) that you can get just as much sound, just as clear and still have the ability to tune it on the fly as well.

I agree 105%...

[ttocs]

I find too often that ported boxes end up pounding in the range they were designed too but then a note out of that range just doesn't have the same impact or clarity. A sealed box now will sound better over the range, and if you want to give the signal a bump in the range you want - no problem.

[Eric D]

Besides, I like how a well designed sealed box can play so low. The lows you feel more than you hear.

I completely understand why people like the additional output of a ported box, but if you planned on say 2 ported 12s for example, why not just use 3 sealed 12s instead? Sure the ported will still likely have more output, but only around the tuning of it. With modern high mass drivers, one can probably stick 3 sealed woofers in the space of 2 ported ones as well.

Then there is port noise. I for one don't like it. My favorite product to combat this is the PNR (also sold by Rockford as well) Aeroport. These help keep noise to a minimum, but it can still be heard depending on the track you listen too.

I by no means listen to techno bass all day every day, but I am a big fan of Techmaster P.E.B. (maybe this shows my age), and ported boxes just don't cut it for most of their songs. Too much port noise, and too much over excursion of woofers.

But, I don't by any means hate ported boxes. They have their uses. Plus really big ported boxes tend to work well in home audio applications.

One box you won't ever catch me using though is a bandpass...

[audiophyle_247]

I find that 90% of all ported setups sound like ass, and I'd agre with Eric & Scott on their comments.


However I said a well designed ported box which to me is ultra low tuning for a near flat freq response that no sealed box without bass boost can match. I cannot stand the freq roll off on a sealed box, and adding subs to get that 35hz louder makes everything else too loud (50hz +). I have also found that boosting the signal to make a sealed sub hit low also significantly increases power demands & decreases accuracy more than a ported box, making the sealed one sloppier.

With a large enough port air turbulence is under control & there is no audible noise, easy enough to avoid with a little forethought. Lol
And a small chamber stupid long port will keep that sub just as accurate as a sealed box (un-bass boosted) but push out 2~3 times the volume in the lower octaves with less power.

The only draw back I see to ported is the complexity in design, error free construction required, and the spatial sacrifices, but totally worth it when I can get a small 8" to hit the low lows accurately and with authority. Lol

[Mr. Wild]

It also depends on the driver. Some _have_ to be ported.

[zeropoint0.5]

For most people it is just a matter of personal taste.....

Some prefer to listen to a sealed one, some to a ported one.....

You can never go wrong with building both enclosures, and then continue with the

one that gives the best result.

If you chose to use just one subwoofer, the sealed enclosure will certainly save you more space,

but a high output vented box will give you way more output !!

I prefer a vented enclosure tuned around about 30hz, but that is personal taste......

sometimes it depends also on witch type of music you want to listen too.....

I would only use a bandpass box in a car where the trunk is totally sealed with metal from the interieur,

so i only have to cut metal to let the port enter the inside of the car......

[Eric D]

Sealed boxes play flatter and lower than ported boxes. I am not so sure this is my opinion, up until this discussion I have understood this to be a fact based on physics. I could be wrong though, or I might not understand the topic entirely.

Since a sealed box is flatter, adding more woofers just adds more output. It does not add more above a certain frequency. The addition of more woofers is a linear relationship.

It has also been my understanding that a ported box adds output at the tuning frequency. Below it the driver "unloads" and output falls off drastically, as excursion increases drastically as well. This is the very reason for the use of subsonic filters. They prevent an amp from over driving a sub below its tuning. Above the tuning frequency the output will be similar to a sealed box. Maybe less or maybe more depending on the situation.

So, if you want a ported box to be flat, you can EQ out the spike in its output, but then you are defeating the whole point I would think. Or, maybe you could EQ some of it out to keep the over all response flatter until below tuning, which might then be flatter than a similar sealed box.

One thing is for sure, unless you do something wrong, ported will always have more output than sealed. This is the number one reason people build ported boxes, you get more out of your investment, but at a trade off most are willing to make (control of the driver).

Increasing power to a sealed box won't make it sloppier, that comment just does not make any sense. If you are increasing power beyond clipping or something, then that would be the reason for it to be sloppier, not the box itself.

I am not trying to argue that ported boxes are junk, and sealed is the end all of everything. Each has its merits. However to make the comment that ported is "ALWAYS" worth the effort is not only inaccurate, it is misleading. I personally am not a "bass head", and instead prefer very accurate bass reproduction, at the expense of being louder than my neighbor. For me, ported is not worth the effort at all, and would be going in the opposite direction of my goal. But, I am not a representative sample of the market for which car audio is currently sold to (maybe I represent a market long since disappeared).

As for port noise, every ported box will have port noise, it is just a matter of how annoying it will be. I don't care how big you make the port, it will still have its own sound to it, which for some people (such as myself), can not be tolerated when sitting close to the enclosure. When RF came out with the Power HX2 subwoofers, I happened to be working for them. I built countless boxes myself, and others did too, as we worked towards developing the published recommended box designs for the manual. At one point I built an 8 cuft box with a 24in x 8in slot port in it for testing, and even this box had port noise when sitting close enough to it (which is hard to get away from when the box is 8 cu ft, unless you drive a school buss). That big ass box had some incredible output, and still sounded great, but it was certainly not for me personally.

[Eric D]

I suppose for some additional information to anyone interested, I need to add some background.

I don't design boxes. I used to around 10 years ago, but I since gave all that up. When someone comes to me now asking about an installation I take a different approach...

First I ask them what the max space they are willing to give up is. Once this is established I start building a box to fit that space. I will calculate the volume of it using math, or if the box is complex, I just plan on using something like packing peanuts to estimate the volume. When I get a feel for how big the box will be is when I advise them on the woofer size to go with, and the quantity.

During this process I do what I can to get a feel for what the person would prefer, either sealed or ported. Most people are easy to figure out with regard to this in a matter of minutes.

If the box is to be sealed, then everything is done. The next step is the rest of the installation, then when done, adjustments to the box can be done if needed. These can be adding polyfill to change the response, or even adding blocks to take up volume. This is more rare, but I have done it.

If the box is to be ported, I may calculate a starting point using port formulas, but more often I pick a size which makes sense, and then temporarily mount it. Once the system is done, I then run impedance curves on the box to get the EXACT tuning of it. It seems most people overlook the fact that the box and the vehicle are a system working together, so calculating a box outside of the vehicle is not going to get you where you want to be. Heck, rolling the windows down on the vehicle changes the tuning.

Once the exact tuning is known, I then will lengthen or shorten the port and retest until it is at the desired point. It then gets mounted.

Way back when, I did some installations using a reference box. I had a 12" woofer in a 1cuft sealed box. I would put this in the vehicle and use impedance measurements and even some frequency response measurements to get an idea what the transfer function of the vehicle is. I then used software to calculate boxes for the desired woofers and quantity. This ended with some great results, but I was never sure the amount of work was justified.

I realize my approach to this is very unorthodox, but it has worked well for me. I would say 90-95% of people have been happy with what I have come up with. The majority of those unhappy were because I misjudged them and built a sealed box when they really were a ported guy. I have a friend of mind with a sealed setup which I would take off his hands in a second. It is easily the cleanest sounding system I have heard, but every time I see him I get "I wish my system was louder", or "my system is not as loud as ***'s system is..."

I guess you can't win them all...

[ttocs]

good debate all around. I too agree that saying you don't like the roll-off on a sealed box vs a ported box doesn't make much sense to me. A ported box has a larger roll-off around the tuning freq. Adding signal manipulation(bass-cube) can make a sloppier signal with out any doubt but I think its easier to adjust that dial down when it happens then it is on a ported box. I also have to agree that throwing more power to the sub as long as it isn't into clipping is better then feeding it too little power if we are talking accuracy.

I can't wait to hear all 3 of my 10s pounding away in my car of course they will be tightly x-over to keep them from messin with the Ti9's in the doors.

[audiophyle_247]

good debate all around.

Agreed, but lets move it to a dedicated thread instead of super-hijacking this one. lol
http://phoenixphorum.com/viewtopic.php?f=3&t=21723

I look forward to the responses, you anti-ported people. lol

[nutxo]

LOL. The whole reason this thread was started was that odd box I wanted to build. My mmats system 2 years ago ran sealed. I ran 1400 watts to a sealed box and honestly the output was a little disappointing. It was very clean but its not like it murdered the lows and it was loud " ish" but not LOUD. The box I was looking to make was not a bunch of random shit I threw together. I did the math and utilized what space I have to get a box with a relatively flat response. I ran it thruogh winisd and got a relatively flat response from 30 to 100ish. I used aeros to save space and offset the the inside of the box to get the inner ports as far away from the subs as possible to avoid premature unloading.

Dividing the box.. I know some people will disagree but to my ear divided sounds better than common for 2 subs. The bass is tighter and more well defined.

[Eric D]

LOL. The whole reason this thread was started was that odd box I wanted to build. My mmats system 2 years ago ran sealed. I ran 1400 watts to a sealed box and honestly the output was a little disappointing. It was very clean but its not like it murdered the lows and it was loud " ish" but not LOUD. The box I was looking to make was not a bunch of random shit I threw together. I did the math and utilized what space I have to get a box with a relatively flat response. I ran it thruogh winisd and got a relatively flat response from 30 to 100ish. I used aeros to save space and offset the the inside of the box to get the inner ports as far away from the subs as possible to avoid premature unloading.

Dividing the box.. I know some people will disagree but to my ear divided sounds better than common for 2 subs. The bass is tighter and more well defined.

What kind of a post is this? Plenty of people gave you some thoughts on your design, and like with many threads, the discussion wondered from the original topic at hand.

I am not going to re-read this whole thing, but I don't remember anyone claiming your design is some random shit thrown together. Obviously your concept with the ports being in the opposite chambers took some thought.

I personally am not trying to sway you from building a ported box either. Maybe others would, but I even doubt that. If you had 1400W on a sealed setup, and it was not loud enough, you NEED to go with a ported setup, as sealed will never satisfy you.

It is great that you used Winisd to design your box, and it is even better that you actually know how to use this software (I personally have never used it, or had a chance too). However, all the modelling in the world will do you little once you stick that design in your vehicle.

Unless you have access to CAD models of the vehicle, the only way to get any idea of how the vehicle will affect the system is to do testing in the vehicle. Typically you would need some sort of swept sine wave analyzer. You can get some results with an RTA, but it won't be as easy. Until you do the testing, the modelling is only good for a large open space (like a living room)...