There are many threads that give you the answer you are looking for, but I try to give you some info here:
Your gear seems to be allright to get the sound you want. As you know Jason used Sadowskys trough SVT-2 (non pro) with miced 8x10 (some di might be involved allso) and guitar head (Marshall 100w tube head I assume). I had a picture about his rig that I found somewhere from the internet, but I have lost it..
If I remember correctly the eq settings for his Ampeg were:
Bass 1 a clock
Treble 11 a clock
Mids 12 a clock
Frequency 3
Graphic Eq is used for uppermid boost (this is hard without picture) Boost 300hz bit, 1khz bit more, 3khz even bit more and 10khz bit les. Making frown from 300hz to 10khz. There might have been slight cut at 40hz. He had 3 Ampegs in a rack, all eq like this. Have no idea if some switches are on or off (hard to tell from picture)
So it`s bit complex to get exact settings.. But if you use your Ampeg eq somewhat like this and play your bass both pickups full, heavy down strokes with heavy plectrum (Jason has Tortex blue triangle and I like them allso) you should get really close...
In my experince it has a lot to do with your bass and playing style.. With my Ash body maple neck jazz copy (alltho it`s passive) I somewhat get his sound, with my other basses I just don`t..
Here is his more recent rig:
I hope this helps a bit.
