It's unbelievable now..this is the first P pickup in this bass that rocked...not just flat and lifeless like most of them...fat, tone galore, mids and highs are there too.

the J breathed new life into this great instrument. It growls, has punch like you dream of..

to quote Dimarzio: The DiMarzio DP123 Replacement Neck & Bridge Pickup Set for Fender J-Bass keeps the crunchy, focused sound of the traditional Fender Jazz Bass tone while boosting gain and response. This additional presence means a bigger sound with improved attack and bite - great for highly articulated playing! The sensitivity and deep tone of these DiMarzio pickups are also the perfect complement to the warm character of fretless basses.

Unlike traditional pickups, these DiMarzio DP123 pickups are individually humbucking. They're not a stack: each coil picks up one pair of strings. By doing it this way they keep the resistance down and the tone clean and clear.

I'm not sure if a mediocre toned instrument can be helped by these pickups, but wouldn't be surprised....Put these in a bass with serious tone capability and they will rock your world...Using roundwounds now but am real curious as to how some Thomastic Infeld Jazz flats would sound with this setup.