I've noticed that all over the internet there is misinformation about how to get Mark Hoppus' bass tone. The typical suggestion is to get a Mark Hoppus signature bass, Ampeg SVT, and 8x10 Ampeg Cab but you can get his tone using any bass setup. The most important thing is new strings. Aside from that start with all knobs at 0 i.e. with no boost or cut. Set your amp with low-mid and high-mid boosted all the way. Treble is boosted halfway (3/4 of the whole knob) and bass is cut a little more than halfway (1/8 of the whole knob). If you have contour settings set the low pass at the same level of cut as the bass and high pass at the same level of boost as the treble. You have to play with the bass and low pass until they just barely take the edge off the mid and treble twang without adding any thump. This should get you as close as possible without buying Mark's actual set up from Take off Your Pants and Jacket which is going to run you about $2,000.