So, I have a 98 4-door 4x4 Blazer & I'm installing a new system. Subs are 2 12" Pioneer DVC (TS-W310D4) on a PRS-X720 (4Ω mono), front are Pioneer component 6.5" with the tweeters installed in the dash & haven't decided on rear door speakers and thats where my question begins.

In regards to the 12s, is the placement of the box something that I should be concerned with or can I just have the box up against the back seat & all will be well? By that I mean will the sound improve if the box is closer to the rear hatch VS near the back seat?

Would ported or sealed be better for such an open space? I know it's more speaker dependent I'm just looking for an overall consensus on what people personally run.

The rear door speaker placement really sucks for people in the front seat. Has anyone run front facing 6x9's (or others) incorporated into (built on top of) the subs box? If so how did it go & was it better than just running 6.5's in the door?

Eventually I will be using the X720 to power the fronts & running either a GM-D9601 or GM-D8601 for the subs. But for the next month or so the fronts will be head unit powered. Also going to need a bigger alt so if anyone has a part#, manufacturer &/or price for a 200W (+/-) alt that'd be great.

 

That is truly something that is vehicle dependent and a little dependent on your own ears. Every setup is different, different subs, different enclosures, tunings, settings etc. affect the way they sound and will change how placement affects the sound as well. The absolute best thing to do, and truly the easiest, is to move it around, rotate it, play with it and find which placement sounds the best to you.


First of all, using a ported or sealed enclosure starts with the driver(sub). Some subs really only prefer a sealed enclosure, others a ported, and some are at home in both. The documentation from the manufacturer will give you an idea, but there's an easy equation called the EBP (Efficiency Bandwidth Product) that is calculated by taking a few numbers from the Theile/Small parameters which should be in that documentation. Using that equation will let the driver tell you exactly what it really works best in. After that, if it's one that is at home in either style of enclosure, it will come down to the sound you prefer the best. I've seen subs in sealed enclosures drop down and play the lowest notes with authority like you wouldn't believe and I've also listened to some in ported enclosures that were so tight a sealed enclosure couldn't touch them. Most of that has to do with how well the enclosure is designed and understanding what compromises you have to make in each situation to get the sound that YOU want from the driver.


In all reality, why are you worried about hearing music from behind you? The music was recorded in front of the band, not behind them, and that's how the playback through your speakers works. Now, to each his own, and if you wanted to put 6x9's in the sub enclosure facing forward you can certainly do so as long as they're not sharing air space (enclosed in there own space) with the subs. That being said, I would highly recommend NOT doing it and I'm not even going to go into the disdain I have for 6x9 speakers. If you concentrate on ensuring your front speakers are installed in the most ideal way possible, doing everything you can to give them the best installation it will go a lot farther for you than what the 6x9's could ever hope to.


I'm certain you mean 200"A" alt and why do you think you'll need a bigger alternator? You're really not going to have enough power on tap to cause any major issues with your electrical system unless you're also going to be running a great deal of lights or something. A "BIG 3" upgrade and making sure you have a good, strong battery should serve you well for what you're doing. Now, I am a fan of excess and usually don't hesitate to go above and beyond the requirement just for the "Just In Case" reasons or even possible future upgrades. Now, if you do find you want a little more alternator you can pick up an AD244 GM factory alternator off of many different full size trucks and other vehicles that is rated a solid 145A output and has on many occasions been measured a fair bit more than that. Pulling one from a pull-a-part yard is a very cheap and easy alt upgrade that just bolts and plugs in with no modifications, except possibly a slightly longer belt. If that's not enough for you and you have at least $400 to burn a 200-250A alt from Singer Alternators (what I have), Mechman, or DC Power Engineering would definitely give you some output to work with. In most cases though, a solid battery up front and even a small second in the rear with the amps is all anyone would ever need with the power you're looking to run.

You need to learn to trust your ears with your speakers though. YOU are the only one who knows EXACTLY how you want it to sound. We can help you get there, but it's really all you in the end. If you're happy, we're happy, even if we think you're out of your mind! (LOL, just kidding)

 

I get what you're saying about sealed vs ported. My main concern is that the bass will sound.. not sure how to explain it .. over resonated. Like when an exhaust leak makes that droning sound within the passenger compartment. I like the bass tight without the bass becoming dull as the note trails off. If that makes any sense. Describing sound is like describing the color blue..lol. I've run both ported & sealed but prefer sealed within the confines of a trunk. An SUV with an open area is new to me.

I will be running 2 batteries,1 up front 1 in the back unless I can get both under the hood.

In regards to the alternator, the current alt is 100A. The current amp (850W peak, around 60 amps draw) has 3 x 30A fuses & my upcoming, additional, amp will have either 2 x 40A or 3 x 40A. So at peak it's going to draw a lot or amps which the 100A alt wont be able to handle. I was thinking the exact same thing you suggested with the 140-145A alt. I can get a new aftermarket (Remey) for around $65 or a new AC Delco for $105. I'll definitely be going with the 140A. Will the OEM cables handle the extra amps or should I upgrade them like I would if I was installing a 200+A alt?

As for the rear speakers. I personally like sound to come at me from all angles. I use headphones a lot & my ears are used to sound being everywhere & not just coming from the front. Having it only come from the front just sounds weird to my ears. I'm still pondering the placement of the rear speakers but my main concern with them is not the sound but the aesthetics of their placement. I don't want 2 stupid looking bulky protrusions. If it ends up looking terrible then they're going in the doors & my ears will just have to deal with it.

I am curious as to why you don't like 6x9's. I have a pair of Cerwin Vega 6x9's in my Z24 that I've had forever & they are some of the best sounding speakers I have ever heard.

 

If that's what you prefer, then run them sealed. What sounds good to you is what matters the most.


Adding the fuse value of your amps together isn't really the best way to determine the draw you'll have. The amps do not pull that amperage all the time, only during musical peaks because music is dynamic or constantly changing in amplitude. Even on the strongest peaks the amp will only draw that current for a split second, not even enough time for the alternator to ramp up and commit to providing the current. Having the two batteries and doing the BIG 3 will be plenty for what you're doing. If you do happen to get voltage drop the 140A alt will be all the upgrade you'll need to make.


Designed correctly it would not be a bulky protrusion, but that will depend on your ability to design and fabricate what you're looking to do. It's a matter of retraining one's ears. A person gets used to hearing music played in that manner and it seems right no matter what the situation is. Think of a home stereo, there's only two sets of speakers in front of you yet you can (should) hear the band playing around you, singer front and center, drums behind him, bass guitar to the left, lead guitar to the right, for example. That's how it is recorded and the playback can be exactly the same as it would sound if you were in the microphones position. In a vehicle that is often lost with speakers in the worst locations all around the listener, it destroys the recording. Headphones work the exact same way as a stereo set of speakers, it's still only a left and right stereo signal, the difference is there's no distance for the sound to travel, no surfaces for it to be reflected or absorbed by, no panels to rattle and nothing in the environment to introduce anomalies in the sound. A well installed, well aimed, well EQ'd and time aligned set of stereo speakers can sound very much the same in a vehicle. It takes time, planning, patience, attention to detail and a little bit of processing to make it happen. The results, however, are nothing short of awe inspiring.


That's the difference between different peoples listening tastes and experience. To me 6x9's are sloppy sounding. The causes of that are odd order distortions that can't be tamed and issues with directional reflections and phasing issues that ruin their ability to give a proper sound stage and keep the imaging accurate. It comes down to a speaker that just has no real use. I'm a little over critical than most people, if you haven't already noticed. I like the sound to be smooth and detailed with a proper sound stage and imaging that gives the realism to the music it was intended to have.