a 10" sub is the best size to go with. now u can put it in sevral different boxes witch will change how it sounds. sealed box is for the best sound quality, then theres ported vented banpass..... ect. now they do make shallow mount subs that dont require alot of room to sound nice. but me i like the big hitting bass so i have mine vented out to about 34hz most people think i have 2 12" or at least a 15" in the back of my jeep. but do pay attention to your rms ratting thats what you want to go by and depending on your amp depends on how it will sound a good buget amp is hifonics there about 80% efficiant. and you wanna do a sub about 2ohms dont go with a class A or B amp there mainly for mids and highs what you want to get is a class D amp (mono) and remember in car audio watts aint jack RMS is what your really looking for

 

Um... Yeah...

While all input is appreciated, let's see if we can interpret what "H-Town" is trying to say.

1) You don't have to have a 10" sub for it to be "the best". Sound is subjective and largely up to your tastes. Many modern 6" and 8" subs, given proper enclosure characteristics, are quite capable of rivaling many 10" or larger subs in terms of overall sound volume and low-end extension. I have computer speakers at home with a 6" sub that will rattle the pictures off my walls. Further, unless you use a very shallow mount 10" sub, you're not going to get the same kind of "factory look" install that I have without a major hack job of your interior panels, or you'll need to buy one of several "custom" boxes that some of the guys on these forums make for sale. By all accounts, they are built well, integrate fairly well with the interior, and will hold 10"-12" subs. Personally, I'm just not fond of the look and don't care to advertize my system to prying eyes that much. However, to each his own.

2) Sealed boxes are generally more musically accurate than ported or band-pass boxes. Ported will get you a nominal 3.1 decibel bump over sealed, but can introduce some exaggerated resonance at certain frequencies. Band-pass will give you a similar bump, but due to their nature often have reputations as "one note thumpers". In reality, they tend to perform very loudly (not necessarily accurately) in a narrow "band" (thus the name) of frequencies; usually about 3/4 to 1 1 1/4 octaves, but outside of that they will have a very rapid falloff in sound, and the frequency transition from your door speakers to your sub can frequently have dead spots. Personally, I like sealed, and many subs designed for small enclosures will actually call for a smaller sealed box than for a vented box.

3) As has been stated in my previously referenced posts, a given sub doesn't "need" any particular amount of amplifier power. Most of the time when you're listening at the 75-85 decibel level, your speakers are only receiving fractions of a watt to a few watts each. Just match up the RMS of your sub, to the RMS of your amp, and while tuning it in, adjust the amp gain so that you don't bottom out the sub at max volumes on your head unit.

3A) Class D amplifiers are technically more power efficient. They can also cost more. On a smaller sub-400 watt system it is debatable whether you really gain enough benefit to justify the premium price. Depends on how good of a deal you find on a D Class amp, but I on something less than 200 watts nominal/400 peak I wouldn't pay more than about a 20% premium to get one.

3B) Class A and B amps are not "mainly for mids and highs". There are a boatload of systems, including factory systems with external amps, that use only Class A or Class AB amplifiers, and they sound just fine. In fact, there is a reasonable argument that Class A amps have the best sound quality, even if they are the least efficient.

4) You do not have to go with a 2-ohm sub. This old argument is also covered in one of my previously referenced posts, and any advantages of 2-ohm subs really only kick in on multi-sub configurations. In a single-sub scenario, you can actually spend more money for both the 2-ohm sub and the 2-ohm capable amp, and because the amp will have to deliver around twice as many watts to the sub, you'll need to seriously ramp up your power wiring and possibly incorporate a capacitor. MORE MONEY!

All that being said, you mentioned you're not a techie so I'll try to make this easy for you.

Get a 6.5", an 8", or a 10" sub that fits your liking in terms of frequency response, and has a 4 ohm nominal resistance and power rating around 125-300 nominal and 250-600 watts peak. And remember, an SPL of 89+ is better than 85, IF you can get it, but it's not a deal-breaker. Then, buy the amp that I mentioned in my build, stick it under your passenger seat and hook it up to whatever sub you bought in the ranges mentioned above. It will power them all just fine on its 200 nominal/400 peak watts. Remember, the difference between putting 400 watts into a sub and 800 watts is only a 3.1 decibel increase. In other words, not enough to warrant the expense, in most cases. With speakers and amplification there is a rapidly diminishing rate of return on sound volume vs. power requirements/system costs once you get above about 500 watts nominal.

If you go the way I did, you can get the 6.5" sub, the amp, and a wiring kit on Amazon for a total of $150. You can upgrade to the 8" version for another $20. Or, get the all-in-one unit you originally mentioned and be done with it. It will also save you the cost and time of an enclosure (although my enclosure was $20 worth of materials) Although, I'm not sure how that's going to look or fit in the back of your XJ.

Best of luck to you. Just realize that there is real math involved in system design, which I've linked to, so don't let people try to confuse/BS you, and that ultimately what is "best" for you is what sounds good to your ears and fits within your budget. I've just tried to give you some info to get the most bang for your buck.

 

check craigslist and make sure you hear it first! best way to save money. i picked up a fosgate 12 and fosgate amp for $100. Mounted the amp under back seat and the 12 in a sealed box doesn't take up much room

 

whew. Thank to all your guys input and advice (particulary macgyver35) Its all starting to make more sense. While the actual box building plan of attack is still being worked out, I think ill go with most likely an 8 in (little of everything) with a higher sensitivity in a sealed enclosure. The amp matching got easier after looking at the math posted that it isnt super important to have a super powerful amp.

then as suggested I browsed craigslist and found one of these http://www.crutchfield.com/p_575P3S2...1#overview-tab for 50 bucks and a RF 10" 250 watt 2 channel amp for 60.

The sub seemed perfect (even though its a 10in) as it is shallow mount, and cheap but theres two downsides I see and I dont know how big of a deal they are= its a 2 ohm (thus needing the thicker wiring), its sensitivity is only 83 db, and its range doesnt go below 40 Hz. how big are these negatives do you guys think? the deal seems great, almost too good... can subs be inconspicuosly damaged?

 

thanks again, after all I learned it seems I might as well go with making my own and know ill get good sound and be happy with how it looks and runs.

 

hey I saw one of your threads and saw you did the whole fat mat lining. hows it holding up?? I've heard so many different reviews Id like to hear a first hand account. I was thinking of doing my roof since I'm replacing the headliner.

 

what kind of music do you listen to

 

Mostly country and rock but I delve into some pop and minor dubstep and other fax machine sex noises now and then

 

just step it up to a 10 and be done. It will sound good with all music. I hate when people waste money on something and expecting more out of it and redoing it all over again. Ive had everything for 4 12's to 18's to 8's. Ive been into audio for almost 15years now

 

Dang that's a repotoire for sure. Yeah Ill probally just get the ten cuz I found a really good priced one. That way like you mentioned I can can get it done and let it be.

 

macgyver35 u do have a vast knowledge of car audio I'm not a pro at it. But I've always have had nice systems. I've always had a problem using class a,b amps for my subs that's y I don't recommend them for subs. But u did get a lot more time to explain a lot that I couldn't do in a 5 min break.

But one thing on vented boxes that wasn't mention is if u build a vented box u have to choose what Hz u want it to be before u build.

 

That is good advice from Macgyver35 and I have to back him up on the class AB comments. Class AB amps are excellent for subs and a good quality AB amp is going to sound better that a cheap class D. Class D is relatively new in car audio. We managed to build some pretty amazing systems in the 80s and 90s with no Class D available! Class D is also relatively new in pro audio yet I've heard and built some pretty awesome stage systems with class AB QSC amps.

Class AB amps probably get a bad wrap in car audio because the most common system these days seems to be the best subs that the buyer can afford paired with the cheapest POS amp they can find. Just look at systems for sale on Craigslist. 80% of stuff for sale is a good pair of subs with a crap amp that probably produced 50% of the claimed power.

My advice, purchase quality components and build the right box for your subs and you will have a nice system. They best sounding shallow 10" (that's not a fortune) IMO is the Kicker CVT 10.

 

Listen to Macgyver...he knows what he is talking about.

My only "complaint" of his advice is that he says sealed boxes are best acoustically...he should know transmission line are the "Best"

Seriously though...don't stress it that much. You'll be happy with ANY sub you add to your system. It all depends on how much you want to spend and how loud you want to go and how much space you want to sacrifice. Even the all-in-ones will be a world of difference to the non-sub system.

 

alright thanks to all three of your input and time spent. As suggested I wont stress to much because im not a huge audiophile but I think Ill go with a tight sealed box and a 6.5 - 10 in.

Im currently looking at a RF shallow mount p3 10 in and 250 watt 2 channel sub that I could get for 100 bucks on craigslist. Does this seem like a decent combo to go in a box that I will build? It seems to fit Macgyvers math theories that he posted in terms of wattage.

 

Ha! You're right! My mind just generally doesn't gravitate toward transmission line enclosures when talking about cars because of the typical space requirements and/or fabrication issues. If you have just the right small sub and mad fabrication skills, it can be done in a way that is somewhat concealed. I guess he could do a simple box with a tapered path, but that doesn't sound to me like what he's after. And I don't think our OP is ready to tackle that the design calculations.

You just reminded me of the transmission line sub setups that were put in the third gen Mazda RX-7's when they hit the market back in '92. I can't remember if it was a Bose system or not, but I do remember all that "plumbing" in the back for the sub. I did a transmission line once for a friend that was a 10 inch Vifa sub mounted to the top of a 10 foot tall hollow decorative column in his house. He had high ceilings and the idea worked for his set up and decor. It wasn't my idea; I saw it done in Audiophile Magazine back in the early 90's and we decided to make our own version. When it was all said and done it sounded mighty sweet, and the lower notes seemed to come from everywhere. People could never figure out where the sub was. God, I haven't worked with a TL in so long I'd have to re-teach myself...

At any rate, I hope the OP has enough info to properly guide him, but not so much that he gets "analysis paralysis".

However, if he chooses to learn more, he can spend some time on www.the12volt.com and pick up a copy of a book I first cut my teeth on: