i have a squier j but i know its the same case with almost every jazz bass with single coil pickups that the moment you turn down the neck pickup for that growly tone the 60cycle hum comes dancing around loud! i personally always loved that jaco'ish tone with full bridge pickup and almost nothing or very little from the neck pickup. for over a year i have been trying to figure out a way to do this. replacing the stock pickup with a noiseless bridge pickup was an option but i knew that they can never sound like the real single coil pickups! so i kept scratching my head.. even with the best shielding that inherent hum never goes away which is exaggerated whenever i turn on the preamp or the fuzz. the lightning just struck me an hour back! it is the simplest (and the best) idea i ever had! i just unscrewed the neck pickup out, removed out the foam and springs and screwed it back as low as i could so bassically i just lowered the neck pickup's height so low that there is hardly (very little if at all) any output from it! so now both the volume knobs are on full so no more 60cycle sicko hum of course its not a ground breaking development and neither i think i am the first one to think of it but am so goddamn happy that i had to share with ya all! i think the output from the bass has gone down but i can crank it up at the preamp so no big deal for me!