Sorry for the long read and as usual thanks to anybody who offers advice. I'm starting to realize the more I learn the more I need to learn. I'm setting my crossovers. 2 way passive comps up front, stock rear fill, single sub.

Headunit options
High pass (slope): -6 or -12
Cut off: 50, 63, 80, 100, 125, 160, 200Hz
Low pass (slope): -6, -12, -18
Cut off: 50, 63, 80, 100, 125, 160, 200Hz

1) I chose -12 slope and 50Hz for the front comps (DLS UP6). It sounds good but is this too low?

2) I'm clueless what to do about the stock rear speakers. I'm guessing -12 slope but what cut off frequency? I believe I'm supposed to make the cut off high so it's less directional?

3) I chose -12 and 80Hz for the sub (JL 12w6 v2 ported to spec). I thought -18 would be better, I think a phase reversal is happening though. Not sure. I can reverse the phase fot the sub at the headunit, at the amp or both. Man I'm lost.

4) After you've figured out the headunit settings what the heck do you do with the amplifier crossovers? I've got a pdx 2.150 powering the comps (-12db slope 30-400hz adjustable x over). I have a MRD M500 powering the sub (-24db slope 30-200hz adjustable x over).

I've gotten some pretty generic answers from literature and by visiting local shops. The advice I get here is always more thorough. I'm hoping one of you guys can explain this stuff a bit better or point me in the right direction. Thanks.

 

Definitely cross the rears as high as you can, and better yet invert the phase one one so it doesn't interfere with the front stage

Its important to note that crossovers also introduce a phase shift in the frequency response:

6db: 90 degrees
12 db: 180 degrees (or exactly OUT of phase)
18db: 270 degrees
24db: 360 degrees

What does this mean? at the crossover point, you need to play with the PHASE of the subwoofer to match that of the front, dependent on what crossover point you use. Don't worry about the slope, 24db isnt really needed unless you plan to cross over much above 150hz. However, if you have access to it for BOTH the subwoofer and the front stage, its usually a good idea to try it since it adds zero net phase shift

Also, if you are crossing over near the limit of the front stage (which is what you are probably doing with that low of a crossover point), then you have to take the roll off response into account as well. For example, 1st order (sealed, IB) alignments roll off at a rate of 12db per octave. So if you cross at this point, you need to take that into account because it adds ANOTHER phase shift of 180 degrees around that point.

My suggestion? If you can turn off the crossover on the amp, turn it OFF. Otherwise, raise it to 200hz. For the component amp, turn it off as well or lower it to its lowest point to remove its influence. Set the crossover points on the HU for 12db for both high pass and low pass. Raise the high pass on the components to its highest level. Start with really heavy midbass music and play it as loud as you want to without distorting, and reduce the crossover point while still maintaining low distortion and not straining the woofer. Don't be afraid to use a higher crossover point. For example, I am using 125hz for mine, subwoofer crossover point at 100hz both at 12db per octave.

Then introduce the subwoofer. Start with the crossover point of the fronts and see what phase sounds best to you (likely inverted). Then play with the crossover point until you get what you want. Remember, nothing wrong with the subwoofer picking up some slack in the midbass. Playing with the subwoofer slope is a good idea once you get it to sound good. Just keep the fronts constant. Adjust one variable at a time

Finally, you need to take the level into account as well. You would be surprised how slightly too much level on the sub will steer the bass back and ruin the illusion of up front bass. Play with the level and remember it. When you want to rock out, raise it to have some fun. Otherwise set it at a level for a good balance of transparency and presence.

Remember, the goal is to have a SEAMLESS integration between the two systems, whether it be at 50hz or 125hz. Any gap in the frequency response will ruin the effect, steering the bass back. So if your comps run out of steam at 80hz, then crossing them over lower is actually worse, since you have that gap.

For this to work to its full potential, you need to isolate and remove any rattles that are audible from the cabin, and if possible add time alignment capabilities. Then you can experiment with adding T/A to the sub or comps. I am using 6 milliseconds on my sub and the bass literally sounds like its coming from the engine bay



Hope this helps.

 

Thanks for educating me. That answered a lot. Can't wait to get home and play with my toys.

 

Let us know if you have any more questions

 

ok i need way more help then this dude, so PLEASE HELP

my car: 95max auto GLE (iffey about)
heres my setup:

HU - im not exactly sure what it is, because dad put it in a while bad, but its not aftermarket, its another stock nissan HU.

Amp - its a KICKER, i think is a d-class mono block. has the red/black output, 12v (power), remote, and ground. it only has one + and -, thats why im guessing its either and mono block or one channel.

1 10'' sub - plugged into the amp

the front and rear speakers, are hooked up normally.

so i toke apart the hole radio, vents, astray, etc. and i found that there are two jacks plug into the HU and there were two more jacks back there that werent pluged in. so i did some reseach (http://www.moodym.com/maxima/audio/m...s/4th-gen.html) and found that the 95 non-bose system has those extra jacks.

heres my problem, the settings on the amp really suck, so i wanna install a crossover. i have an ALPINE crossword (dont now what type), my dad used to have this crossover in his truck, which as far as i can remember always had a SICKASS system. so i know its good.

so i was wondering how could i hook this up. the crossover has a wire for ground, remote, and battery. and of course red/black outputs for front, rear, and sub. it also has a red/black for input.

the HU doesnt have the red/black so i cant jus run it into the crossover and run all the speakers to the crossover. and right now i dont want to change the HU.

if u look at the diagram on that link (http://www.moodym.com/maxima/audio/m...s/4th-gen.html), the extra jack has a wire for power 24. i was wondering if i could run that wire into the battery plug for the crossover, made it its own ground (using the amp theory and just run the ground wire though are screw thats screwed into metal. if you look back to the diagram, take wire 10 ACCESSORIES (which is pluged into a jack into the HU). strip a piece of the wire and mesh that with the remote wire for the crossover. and then just run all the speakers into the crossover. my question is:


WOULD THIS WORK??????????