Hi guys,
I need some help on setting up the crossover settings on ny head unit. I have the Alpine IVA-D900 and it allows you to set frequency ranges for all the speakers. Will adjusting this make any difference, or will the amps crossover points simply be the end control of what reaches the speakers?

Front Speakers: 48 Hz - 25 KHz ± 3 dB
Rear Speakers: 53 Hz - 22 KHz ± 3 dB
Subwoofer: JL 10WD6 - Not sure on this...

Any suggestions on setting this up?

Also, how important is time correction? Will I notice anything by changing it?

 

I would start your front speakers at anywhere from 60-100hz and let them roll off naturally on the top end (still use the x-overs that came with the to protect the tweet). The rear speakers I would start anywhere from 100-250hz depending largely on what music you listen to and how you listen. As far as time alignment goes I use mine and it does give you a better focused center image and stage but it depends alot on where the speakers are mounted and how close the tweet and midrange is. Then you factor in how they are aimed and how they are phased. There is alot to look into and to really try and tell you everything you need to know online would be impossible because it really comes down to listening and tweaking to make fine tuning adjustments. I personally would not even use the x-over's on the amps and instead would use those on the IVA-D900. My suggestion to give you a start point would be to delay the passenger side 2.20ms and then fine tune from there by adjusting phasing and delay unil you get it sounding right. If you have never listened to a really well tuned car audio system then I would first start by finding a winning system to listen to and then try to duplicate it. What area of the country are you in? I may be able to tell you of somebody in your area that has a top notch system for you to get an idea on. Otherwise, you could go to a high end home audio shop and let them give you a listen for reference. Oh, and when I say high end I don't mean Circuit City, Best Buy or any of the other big box chains. I mean a smaller home audio focused store that all they do is home theater and Hi-Fi. Here is a tip, if the store doesn't have high end turntables and/or CD players in the several thousand dollar range just walk out because they are not serious. Anyway, once you get a reference of what great sound is then you can really tune your system in perfectly. Other options are to go watch some live Jazz, Orchetral or Blues performances and preferrably get a good mental image of how it sounds. What would be even better is if you could get a recording of the same songs by the same band that you heard live and then try to duplicate how that performance sounded.