I looked up your manual online, I suggest you read it.

It looks like the9835 was the 2004 predesesor to my unit the 9855, so has much the same functions.

Make sure you re-set as soon as you power up for the first time. Just like the manual says.

First, there are 2 switches on the bottom of the unit., one is for setting it for external processor, and if thats on, it would sound really bad, the second is for setting it for 2 or 3 way crossover mode. And again, if it's wrong, it would sould really bad. You didn't say how you're set up, i'll assume your running front/rear off deck power and the car has a built in crossover for the tweets?

second, you need to set crossovers and time alignment to match your system. I would suggest using the alpine i-personalize online configurator, downloading, burning onto cd, and uploading it to your deck.

Otherwise, get yourself a pot of coffee and a pack of smokes, bring your manual and magnifying glass and go through the procedure for setting crossover points and slopes for each of front, rear and sub.
(Hope you have the correct outputs hooked up where they should be.)
Then you need to set time alignment for all six speakers.
Get another coffee and more smokes, recharge your battery.
Then there are EQ settings and sub settings.

Once it's set up right, that alpine should blow away your JVC for SQ.

On the other hand, if you bought it used, and it's got a problem, that could be a whole different story.

__________________
Alpine CDA-9887, TUA-T500HD, CHA-S634, CHA-1204 & KCA-410C
Pioneer TS-A6981, 6 x GM-5100T
Kicker 2 x CVR15,
MBQ RCE-216
PG MX2
Soundgate LanStar1
PAC SWI-ALP