KU40

Reliability. Is the amp going to last longer than 6 months? It's just like anything else electronics- cheap stuff burns out faster.

On the Alpine head unit the subwoofer setting likely controls the subwoofer RCA output if it's like my Alpine. That's fine to turn up, in fact I'd recommend setting the amp gain with it all the way up. That setting is not a bass boost. It adjusts the overall level of the subwoofer output relative to the signal strength of the interior speakers. The "Bass" part is the bass boost.

Yes. Just use 3/4"-1". I hope you have a bit of money to spend on it.

No, multiple ports is fine. Many people do it. But unfortunately ports don't work the way you envision. The tuning frequency isn't dependent on volume of the port, it's the relationship of port area to port length. You're not going to like me when I say this, but if you add another 3" port, each port actually has to be longer. Here's what I would suggest. Get yourself a 4" aeroport. If you're really scrapped for space, you might be able to get away with it. I think they arrive at 16"? Anyways, leave it as long as you can and plug it into the box. A 4" port at 16" long would leave you approximately 1.7 cubes tuned to 32 hz. That's about the best you can do to keep the internal volume as high as possible while having a chance that you won't have port noise (although you still may). How did you get a 2.4 cube box? According to my calculations with the dimensions you described as being the outside dimensions and assuming 3/4" wood, you have 1.9 net volume inside the box.

If you cannot feel an obvious leak with your hand, one trick is to lightly sprinkle baby powder or the like around the edges. Any puffs of air coming out will be noticeable with the powder.

Bummer

Ask yourself if that extra money is worth 1-2 dbs. Doubling power theoretically gets you 3 dbs, but as many a competitor will tell you, the real world results are generally in the 1-2 range.

But it's not unheard of. Look at Ford/Mercury, Chevy/GMC, etc. Not to mention all the regular knick-knack consumer products that have a brand name and "budget" brand that are the exact same thing.

Exactly, do it right the first time. Piecing together like you plan is perfectly fine though, just as long as you have one solid end goal in mind. I'm not sure what the capabilities of bass box pro are. I have always used winISD, and in it you can plot the frequency response of a sub in a given box. However, you must realize that the frequency responses given in these programs is in a perfect environment with no resonances or cabin gain. Once you put the box in a vehicle the frequency response will change. However, at least going into the situation with a good box in the first place is the thing to do.

You know that you can bend the port, right? Put some 90* angles in there and turn it to run wherever you want it to. Is your sub firing backwards with the port up right now? That might be your problem. Subs normally work better if you can load them off of a surface, like the rear bumper. If you can, try pushing the box to the back of the trunk and have it only a couple inches from the bumper with the sub firing backwards. What if you scrapped the idea of porting through the rear deck and just did a backwards-firing setup? Otherwise, if you want to port through the rear deck, I'd recommend sealing the trunk off behind the box and firing the sub forward, because right now what you basically have is the port sending sound one way and the sub sending sound a completely different way and into two separate chambers (trunk for the sub, cabin for the port).

Some people on a street corner by work were holding up signs that read God hates fags and you will eat your babies. One of them was stomping on an American flag. There needs to be a dumbass clause for the freedom of speech amendment.

It falls off big time at around 44Hz and only gets worse from there. My subs suggested ported box size is anywhere from 1.5-2 cubes each. Something I didn't know at the time is that the size box you use/build should be determined, in part, by how much power you're going to run to your subs. The way I understand it is that, in general, if you're underpowering your subs then you want to go with a box on the bigger end of the scale, if you're giving them rated power then you want to go with a box that's about in the middle of the scale and if you're overpowering them then you should go with a box on the smaller end of the scale. That being said, and considering that i'm running my subs at nearly double their rated rms, I should have gone with a box that's about 1.5 cubes per sub.....my box is 2.0 cubes per, so it's too big. I'm not getting full power out of the amp because i'm running it at 2 ohms, it makes full power (as far as what it's maximum output rating is, which is 1470 watts) at 1 ohm. I can't wire these subs down to 1 ohm and even if I could it's not likely that they'd be able to handle triple their rated rms handling. So since my subs are rated at 250rms, and i'm running them at 2 ohms so the amp is putting out 870rms, that means each sub is getting 435rms....that's not almost twice their rated rms?Do you think I could get away with running a 160a H/O alt, or should I bite the bullet and go with something in the 250a range? I took your "full power" comment to mean at the impedance you were running the subs at. Not what the amp could do at 1 ohm. I figured perhaps you toned the gain down from the full 870 watts or whatever at 2 ohms so that it was around 500 watts. But even still, have you tested the output of the amplifier to see if you're actually getting all of its rated power at 2 ohms? While box size does manipulate power handling, that is the last thing I would base my box size off of. I care more about the response of the box than the power it will handle. So what size ported box are you going to make for your new 12s? I would rather have the larger alternator, at least 200 amps. If you're already spending a bunch of money on equipment, what's another 50-100 bucks or whatever it is to go from a 160 to 200+ amp alt.

So you are totally against having any of the port inside the box?

I don't see why you would want to set the gain at 40 volts then use the boost to get it up to 45. That will not only provide the same power as just setting the gain at 45 in the first place, but doing so would increase a hump in the frequency response. What you're likely getting now is probably something like 130 db at 20-40 hz, 135 db at 40-50 hz, and 130 db from 50 hz +. The hump at 40-50 is because of the bass boost. Is that the kind of response you want? Granted this is not a given since you would need to play test tones with a mic over all the frequencies to prove this, but this is generally what happens when you use bass boost. Yes there have been needs to have the gain all the way up. The gain is just a potentiometer to match input voltage to your head unit voltage. If you set your gain with the head unit at, say, volume 3 out of 40, you won't be getting much voltage down the line and will need to turn the gain all the way up most likely. The gain is not a "dirty" knob, where turning it up is always bad.

Do you know how big the enclosure is for the towers and what they are tuned to?

Either 150 or 200 will work fine. Doesn't really matter that much. Once you put it in, there's a 99% chance you will never think about it again. It's not like a gain setting that has to be just right. Just as long as the fuse is at or under the current carrying capacity of the wire, which there are numerous websites that tell you that information.

This is exactly what you do NOT want to do. Doing this is what causes clipping. If you set your gain to say 45 volts or whatever with the bass at 0, then you increase the bass setting on your head unit, the voltage at the amp will increase to, say, 50 volts. But if 45 volts is the maximum unclipped power the amp can provide, that extra 5 volts leads the amp into clipping and/or is just more power than you set up the amp to send to the sub. Your voltages at 2 ohm and 1 ohm will be close to each other, because multiply out what's in the parenthesis. 2 * 900 = 1800. 1 * 2000 = 2000. The square root of those numbers will be close. Your bass on the head unit is a bass boost. That will increase the bass at a certain frequency, like 45 hz. Basically you'll get a hump in your response (in addition to possible clipping). I will say this again- turn up the gain before using the bass boost. I guarantee you that if you use that bass boost, you are basically moving the gain to 0.2. The extra loudness in the sub using the bass boost has to come from extra power, right?

Yeah, you have to figure out if the bass feature on your head unit is a boost or just an overall voltage increase. If it's a bass boost (a boost in output at a given frequency, like 45 hz), don't use it. But if it's a level adjustment, as in it affects the signal as a whole just like a volume knob, then you can turn that all the way up as Jaycee said. However, I'm guessing that since you're just using high-level inputs (correct?), that it's just a bass boost. As far as I've ever known the overall level adjustment are only for if you have a dedicated subwoofer RCA output on the head unit. They have front, rear, and sub RCA outputs.

Have you had a system on that alternator before? It's gonna be stressing.

Why don't you just post your dimensions and specifications desired.

Exactly what high bass frequencies are you lacking? I don't understand how you can say the current two 12s ported box is too big, yet plan on buying another two 12s in ported boxes. If you know you aren't getting full power out of the amp, then you aren't sending the subs almost twice their RMS. You cannot run 2200 watts RMS on a 105 amp stock alternator.

There's nothing wrong with a 24db slope on the lowpass filter. If your system isn't even close to its limits, you can turn the gain up.

OK, hold on, this is all getting confusing. Start over. List the dimensions of the box and what you want to do with the port and what limitations you have with where you put it.

Cold won't burn voice coils. Too much power does. If the voice coil is messed up, as it seems to be, that is just from putting too much power to it. Even if it's the tinsel leads messed up, after 6 months that's no longer a manufacturer defect, either. Overpowering a sub will eventually kill it, sometimes it's just a little-by-little process.

Honestly all you have to do is use four butt connectors and plug in RCAs. Can you handle that?