changing the LP will not damage the sub as ive being told before, right?
my LP has 32Hz to 320Hz - currently set on 32Hz
my HP has 10Hz to 100Hz - currently set on 10Hz

so you said put the LP on 100Hz, what about the HP?
and what are the effects of doing so?

 

You're taking what I said out of context, nobody is saying two seperate things.

With the amp gains set high you're sending unclean power to the sub, which will damage it more-so than the bad box. You can damage the sub because of the box though. If you have a leaky sealed box than the sub is going to be sloppy and as a result succumb to distortion (which is a speaker killer). Your port hole isn't big enough to let the air in the box breath and so your box is already performing like a leaky sealed box. If you were to block the hole than the sub may perform the same but it will last longer. I think sealing it will be louder because with that small of a port, albeit little influence, it will tune it somewhat to 30 Hz, and the some-what sealed theory is tuning it to around 35-40hz, which means two frequencies are trying to play at once and they're both cancelling eachother out and causing distortion. The box is essentially making the sub work against itself.

Porting only gives you +3 decibels at the tuned frequency and it doesn't get louder below the tune - the opposite happends. Porting is more or less a specified compromise.

1.6 cubic feet ported or sealed is too small. Don't use less than 3 cubic feet ported and 2.4 cubic feet sealed. Alpine recommends 3.5 cubic feet. Use up to 5 cubes ported and 15 cubes sealed.

I didn't say that sealed = louder. Just in your case, yeah, it might be because it's a poor ported design to begin with. In the correct design, ported is louder. Ported is not "way" louder below 140dB (you should be putting out 130dB). The difference between 137-140db I cannot even tell, it's miniscule. 150-153 is a MUCH bigger gap. With your output goal of 130dB you're not going to tell the difference between sealed and ported - not with all that box-flex from the paper-thin .6" MDF. +3dB is miniscule starting at 130db. You would probably be louder with a giant sealed box (like 5+ cubes) over a 3.5 cube ported box, and you'll like the SQ and low end more.

Block the entire port with a towel, all 6.5" of it. A very secured towel. Test it and let us know what you think because we don't often know of people using designs like that. This is good for future reference.

In English with a picture:

This is a QTC graph for use with sealed boxes. It measures how loud a sub can play whichever frequencies that it'll be handling in comparable air-spaces. Notice how it's not a flat line? That's because it can't play each frequency at the same loudness. You can pick which line you want (simply by changing the air-space), the turquoise is the most space and gives better low-end while the violet line is the smallest box, it will have less low end and seems a little peaky. The turquoise line has less high-end while the violet has a louder high-end. Turqoise = QTC .5 and violet = QTC .9. Frequency response.

 

High pass allows frequencies above x value to pass and blocks frequencies below x

Low pass allows frequencies below x to pass while blocking values above x


As for dual-pass setups like that they work a bit differently in that they just won't interfere with each others frequency band

Anyways, if you seal the enclosure I would run from 10hz on the HP and 100-120 on the LP

With ported I have no idea what your tuned frequency is and do not have the knowledge to determine what it is so I can't comment on what your pass(es) should be set at.

Edit: And yeah.. Sealed really is just a nice simple solution. The sub has complete control of its movements and will operate great within it's design parameters. Ported is definitely for when you know what's what.

 

... and like I mentioned before, you can take out that 4x6.5" port and stick in a 8" port but with your trunk height it will be tuned into the high 40's. If you could re-locate the port and use a 8x22"-long port than it will be tuned to 34.87 Hz and that is good. Still though that sub will create a lot of pressure inside the box and I'm willing to bet that it'll just fall apart so like n0catchyname said, just get a custom box.

... unless you want to take it out and glue another .6" box around it and re-locate the port.

By the way an 8x22" port is like $25-$50 lol.

 

The new type-r 15" models better than most subs and I've modelled most subs. It's like Alpine knows it will be sealed more often than ported -_-. Flat in 2.4 cubes @ 36hz is hard to come by.

 

okay. i guess ill make a box then. you convinced me
for now ill just cover the ported hole and as Dilatory said, set the LP to 100Hz.

ill go with a cubic box.
so i need 5 ft^3 box volume correct? (not including the sub in or anything)

Width: 30 inches
Height: 13.5 inches
Depth: 29 inches
Thickness: 1 inch
=
Interior Volume: 5.03125 ft^3

would that work? the bigger the box the louder it is right? this box that ill make will take most of my trunk so great

 

Does your rear-seat fold down? It's easier to fit a box inside the trunk that way. How much space are you comfortable with the box taking up? Square off the cabin-to-trunk opening and give us those dimensions to work with. If it isn't square than give us all 4 dimensions (as in the two differently shaped squares).

Not quite. For a high-frequency SPL burp-box playing only one tone frequency a smaller box is best (up to a point or obviously it's free-air). A box cannot make use of a low-frequency tune (like 30-35) unless it has the space to accentuate the lows. Generally more space = lower tune & smaller = louder. You'll have a hard time making a small box get really low, it'll drop on its face after the port tune. For instance this is why companies will suggest lower port tunes for each of their larger-sized subs, it just makes better use of the low tune. For every time you say "louder" you'll have to also say "at ____ frequency".

5 cubes with an 8" aeroport (10" of port area per cubic foot) would be great. 1" MDF with a 2" face (baffle = face = where the sub is), the sub sunk 1", three 45-degree corners as in two in the NET space and one in the port (hope you have access to an angular table-saw for an angled cut/home depot can do that too), resined (as in fiberglass resin) on the inside & outside, clamps, really good wood glue, and lots of screws (dunno what length/someone will/don't google it that'll be misleading).

A night & day difference.

Here's what a ported 15" in a trunk can do (150dB @ 32 or 33 or 34 hz can't remember), that's with like 2000 watts.

http://www.youtube.com/watch?v=zMipcT5z1Qc

 

my rear seats fold but there is no way to fit a box through there.. there are some walls and speakers and all that on the way. the trunk is the only way.

so what volume should i make a sealed box to get loud bass and safety for my sub? 2.4, 3, 5?

the lower the Hz the louder it is right? so i prefer loud lol i dont know the Hz number.. i know that my trunk in my civic can probably hold up to maybe 7 ft^3 volume, i didnt measure the exact numbers though

 

I don't understand. Your rear-seats fold but what are you saying, there isn't a hole there? What do you mean there will be a wall and speakers in the way? Why would you build a box to even touch the rear speakers in the rear-deck? Obviously you wouldn't build it big enough to hit them. What do you mean "walls"? Like the wheel-well housings? Why would those be in the way? How are they not in the way with your current box? I don't think you understand what I mean at all lol.

Here's what I'm talking about:



Stick the box through that hole and into the trunk. How would anything be in the way if it isn't already?

Again, no. Lower frequencies are harder to get louder. This is why high-pitched sounds can be so ear-piercing (like a siren). Bass doesn't hurt your ears at all, it's distortion that will hurt your ears and it doesn't have to be loud at that.

A musical tune is considered to be between 30-35 hz.

That sub will work in (sealed) 2.4 cubes (flat response - the red line in the graph) all the way up to 15 cubes (more like the turquoise line).

You can make a ported box easily, it's not like it's much more work than a sealed box. Few more cuts and some sanding, really. You wanted louder so go ported.

These are quality. Made by Thumpper (of PoundThatSound), who is also in BC.

 

I should also say that lower frequencies travel further, and that even though you might score louder on a meter it won't always sound louder because of the pressure. A sub might hit 150 at a high frequency and a sub that does 140 at a much lower frequency will SEEM louder because it's more violent. It's hard to say that lower = louder but I know what you mean.

What are you listening to anyways? That should have been my first question -_-.

If you have the LP & HP set properly than a sturdy ported box isn't going to damage your sub unless you're playing orchestral music that dips below 20 hz (you can't hear below 20hz, nobody can). For instance most of Jeezys' songs are from 32hz at the lowest and 50hz at the highest. 35-40hz is where you really feel heavy vibrations in music and is where the acoustical spike is inside a vehicle cabin. Every vehicle peaks at a different frequency, even the same model of vehicles. There are different peaks too, for instance you might see a gain at 43hz and 70hz. Because of cabin-gain, for most cars like yours a box may be tuned to 30hz but it will still be loudest at 38-42hz.