I originally had two dual 4Ω 12" Alpine Type-R subwoofers. I blew one subwoofer; don't ask me how, it just one day completely sealed/locked-up on me. Instead of just replacing the blown sub with another Type-R, I thought I would upgrade. Thus, I bought two 12" Alpine Type-X Subwoofers and installed the good Type-R in my Jeep (winter vehicle). Here's what my current set-up looks like:

Since my sealed box was custom made for my Type-R, I have to modify it for the Type-X. There is about 1 cu. ft. of volume per sub in my current enclosure. I made the mistake and ported my original sealed enclosure without doing any research. I installed two 3" port holes. It sounds like shit! When I cover my hands over the holes, they sound twice as loud. The wind whistling through the holes sounds like my entire car is rattling even at low volume (which it is not actually since I had my entire whip wrapped in Dynamat). Here's how the porting turned out:

Should I cover these port holes or build a new box? Sonic Electronix recommends the following box volumes for the Type-X: minimum sealed - .66 cu. ft., maximum sealed - 1.25 cu. ft., minimum ported - 1 cu. ft., maximum ported - 2 cu. ft. I originally went with a sealed enclosure for my Type-R's because I love low-end bass. However, I am weary of going sealed again because I am afraid I will blow one/both of my Type-X's. What do you guys think; should I go with a sealed or a ported enclosure for my Type-X's and what volume?

 

Personally, I'd run ~1.5 cubes per sub net volume ported, tuned at 32-33hz, in a common chamber. You may be able to modify your current box, but I highly doubt it. The only way you'd be able to do it would be to run external aero ports. You could start out trying that, then if you don't like it, build another box. Personally, though, I'd just build a new box right off.

 

Wait a second...

You are saying you don't know why you blew one of your subs, yet you have a box that has holes cut in it randomly? You didn't port it, you put holes in the box, right?

Son, putting a hole in what was a properly sealed box makes the box pretty much free-air, infinite baffle, AKA no air spring for the sub to work off of. You destroyed your sub most likely because it was flopping about like a wet fish on a sundeck at low frequencies.

Definitely have a box properly made to the dimensions required of a Type X. Hint: Go big, and use polyfil to get more F3.

 

fourthmeal, I have to disagree with you on your box suggestion. You're calling him out for cutting holes in his box which significantly decreases the amount of backpressure on the sub's cone, which could cause it to bottom out. Would this ruin a sub, yes. Would it lock up without making any strange noises, no. Since OP didn't mention any crazy noises coming from the sub before it locked up (which you would've heard had it been bottoming out) I highly doubt this was the case. But then, you say he should use a big box for the Type X. That will put more stress on the suspension of the sub than a box with a 3" dia hole in it.

And simply putting a hole in a sealed box will not act the same as Free Air or Infinite Baffle (which are quite different things). It will then be a ported box with a port length of 3/4" (assuming 3/4" thick material) and a port area of (1.5)^2 * Pi = 7.0686 square inches. This will give you some very high tuning, which will cause the box to sound like shit, as OP described...

 

What amp are you running and how is that setup? Also, alpine subs are not necessarily meant for ported boxes. Yes, you could do it and it will work fine with proper tuning of the enclosure, but these subs have higher qts values which normally call for smaller sealed boxes or really good free air setups. The type x's sound really nice in a proper free air setup with a really nice flat response.

 

Be mindful that below that very high tuning point, the meager 3/4" hole no longer acts as a column of resistive air, and so the box is now "free air" / "IB". Those two things are 100% exactly the same, at least in implementation. There is no reason on this earth you would want a free air sub to have its back wave contact the front, therefore when using the term free air it is understood to mean IB. There, in the world of the internet, the terms are used mutually.

Moving on to the box...If you have two 3" x 3/4" holes, I'm pretty sure this nulls out any tuning point (probably will get a calculation error) and you've effectively made the box IB...EXCEPT for one very valid issue and that is that when you run IB and then have the back wave reach the front, you could have intense cancellation effects. Do this, and you might wish to crank up the volume to get more out of your contraption. Do THIS too much, and you'll surely kill that sub, possibly thermal it. We're not there, I don't have the sub in hand to deconstruct it, I can't prove it. But I bet it is smoked or dislodged at least.


We can all agree it isn't a way to make a box!

 

Infinite baffle = front wave is completely separated from the rear wave. This generally involves a baffle that is completely sealed to the car. Open the trunk (generally where the rear wave is "housed") and you have an effectively infinite enclosure that is the earth's atmosphere.

Free Air = no enclosure. So this could be the sub sitting on a test bench, mounted to a baffle that's not in a box, etc. There are several ways to free air a sub.

It's really that simple. They are nowhere near the same thing.

And playing well below tuning will not create an IB effect. You have rear wave escaping through the hole, which is no longer separated from the front wave. Will it sound good? No. Will the sub unload because of the lack of cushion on the suspension, quite possibly. And yes, that would damage the sub, as I mentioned earlier.

 

<sigh>

http://autospeed.com.au/cms/article.html?&A=2940

quoted:
A speaker designed for a ported enclosure has certain characteristics, and a speaker designed for a sealed enclosure has other, different characteristics. The same applies for a free-air application. That’s not to say that there isn’t some blurring together of the categories – some drivers can be used in both ported and free-air applications, but for best results, you want to use a driver that is designed to work in your specific application.
There are two ways of obtaining such a speaker. The first is to buy new – look for a manufacturer that lists the speaker as appropriate for a free-air or infinite baffle application. (See Installing a Free-Air Sub for a story on installing a new free air sub.)




Secondly:
http://www.caraudiobook.com/car_audi...fer_system.htm


Enclosure Types

Infinite Baffle "Enclosure" The simplest enclosure type is an infinite baffle or free air system. Note: Free-AirT is a trademark of Stillwater Designs (Kicker) In this system the woofer has the front of its cone isolated from the back of its cone by mounting the woofer to the rear deck or on a board placed across the back of the rear seat.
Advantages of this design include simplicity, minimal occupation of space and lower cost due to not having to have a box type enclosure.
Disadvantages of this design are a larger power requirement, difficulty (sometimes extreme) in completely isolating the two sides of the cone from each other, and slightly less accurate sound reproduction.





Are we done?

 

Sealed boxes are actually the healthier enclosures for any speaker because of the air cushion they have, assuming everything else is absolutely perfect, though I have never seen the box be the weak link..

Sounds like your amp has some tuning issues, because the way your sub went out indicates excessive heat. Upgrading to the Type X will mean you should also upgrade the amp, to something that will push them properly. I would go for a sealed enclosure, separate chambers, around 1 cu ft (+the volume of the sub, of course). I would also make sure you are using a legitimately sized, name brand, power kit.. I have seen amps wipe out subs when they cannot pull the power they need to.

The box is totally up to you and depends on what kind of bass you like. Sealed=tight, accurate. Ported= efficient, boomy. I build boxes for Type R's all day long at Best Buy and will tell you that if you're going with ported, build it to Alpine's specs, because they have done all the hard work for you. Just be aware that the boxes need to be BIG, especially for the Type X. Box design isn't for amateurs, and its really easy to end up with one that doesn't give you the sound you want.

 

Hey guys, I'm new to the site so i hope you can help me out.

I have Currently *** 15in Kicker Solo baric L7, Rockford Fosgate T-1500-1BD, Stinger 2 Farad Capacitor

i just need help with choosing a OEM interface, so i can use my Stock navi in my 2007 Acura Tl Type-s. i have been looking at the Alpine Vehicle Imprint, but im not sure if i should just do a custom radio install and just put an Alpine in?!

I also need help on choosing the Speakers, my price range is $600-900.

please help me out guys,
thanks, mike

 

Well, considering you proved your own point wrong with that post (completely isolating the two sides of the cone from each other) then yeah, I'd say we're done. Go on any legitimate audio forum and start this discussion, and you will be proven wrong very quickly.

1. Ported box have an air cushion as well. Anything slowing down the air will cause an air "cushion". This could be the dash of the car, the back of the enclosure, the guy sitting in the drivers seat, anything. Oh, and I've seen the enclosure be the limiting factor several times in competition. In fact, that's where most of the time/money is spent for competition audio setups, and there's a reason for that.

As for the sealed box being "healthier" than the other types of enclosures, I have to disagree. Like you said in your 3rd comment, all enclosures serve a purpose. What you want out of a setup will dictate the enclosure used. For example, if you want SQ, there are a couple of ways to go. Most will tell you sealed, but you can also use an IB setup (provided you're 100% sealed off), a bandpass, or sealed. These are probably your top 3 choices, but again, you can really do whatever you want. For SPL, there are several choices, and all can be equally effective, with the right equipment. Again, it's all in your goal for the system.

2. I agree. He needs to have his amp set up properly to get the full sound out of any speaker setup.

3. Common misconception that ported boxes are very boomy. In fact, they can (rather easily) be designed to not react that way, depending on the sub you're using. As for Alpine doing all the research for you, maybe and maybe not. I was told by the owner of AudioQue (an internet based audio company with amazing products) that they're recommendations are given with the idea that given rated power, this will be the best performing enclosure. However, "best performing enclosure" is completely dependent on the car. What works in a crx will not work in an SUV. Hell, what works in 1 crx probably won't work in another of the identical year, model and options. Just a little heads up for someone building a crx for SPL, they're all different and all very finicky. You're right though, box design is not for amateurs. I've said it once, I'll say it again, the enclosure will dictate most of the sound of a sub (or even mid) setup. So it is the last place to skimp.

Thread jack much? Start your own thread instead of posting in here...

 

You didn't read that, then. It states specifically "Infinite Baffle, or Free-Air applications.

"Infinite Baffle "Enclosure" The simplest enclosure type is an infinite baffle or free air system."

"The first is to buy new – look for a manufacturer that lists the speaker as appropriate for a free-air or infinite baffle application. (See Installing a Free-Air Sub for a story on installing a new free air sub.)"
http://autospeed.com.au/cms/article.html?&A=0333

You will see that they interchange the terms, they are not exclusive.

Don't speak down to me like I don't know audio. If there is ONE thing I know, it is audio. my username is unique and used in all places I visit, so this notion can be disproved immediately with a simple search. You are not talking to a novice. Let's both agree this is a semantic issue, where we're both talking of the same product and purpose and leave it there.

Now to deal with the actual issue and cease this back-forth of semantics, from some actual real-world experience. A little while back I met a friend that did a similar thing to his box. In this case he simply pulled the speaker terminal box out of the enclosure, leaving a 2.5" x 3/4" round hole. The speaker's response was, of course, horrible. The cancellation effects and lack of proper tune caused the sub to "unload" as if free-air at almost all frequencies tested. This flopping about damaged the speaker but did not lock it up (YET). The thing about it was that of course at the driver's seat, the cancellation was so strong that the gains were cranked to "11" to attempt to compensate, which only exacerbates the issue. The subs were stretched a bit but not ruined, so the solution here was simply to reattach the terminals and seal the box back up. Your situation may have gone beyond that.

 

Where did I call you a n00b? Not on here, that's for sure. I don't care if you hold several world records, you're wrong on this. The thread you linked is an IB build, not a free air build. A free air "build" would be just a sub sitting somewhere receiving power.

Examples:

Free Air:
http://www.youtube.com/watch?v=PMryX5t40q4

Infinite Baffle:

 

Sir, the words are interchangeable, the links proved my point, you are reading them as if they are talking about exclusive terms but it isn't. But whatever. Owning a pack of Alumapros made for "free-air" application http://alumapro.com/docs/alchemy_mxfa_10.pdf , that company uses the term to describe the same thing as IB. Some brands just call it one thing, some another. Exactly like you might call a sealed box an acoustic suspension model, or a ported box a bass-reflex model.

I'll give you this, it isn't an accurate way to describe it as infinite baffle is, but we all know in the world of audio that terminology is quite loose. The reason all of this popped was simply to explain that when someone is "free-air" on a sub, they have no cone control from an airspring restorative force, nor a resistive force of a column of air like a ported box.

Either way, you can have the last word if you want it.

 

another pointless thread

 

Fourthmeal and matt, you guys are not helping the OP at all, hijacking his thread to argue is pointless, either help answer questions about what he's asking or gtfo with this stuff

 

I understand. I am trying to help but semantics got in the way. I'm trying explain that those holes are a huge issue, and very likely the cause of the damage or at least a big contributor. A new box or at least a repaired box properly sealed must be considered first before ordering any new equipment.

The first post questions whether or not to go "sealed" for fear of damaging the equipment again. I'm simply stating that the box wasn't actually sealed at all, and that is where to start to fix the issue.

Copacetic?