I just installed new aguillar ag 4p/j-hc hum cancelling bass pickups in my american deluxe p bass. Which already has fenders active circuit. The bridge is dead silent but the neck pickup is humming. Also when i turn blend knob to 50/50 it sounds like a notched wah pedal. When i touch the bridge the hum goes away. However I play nylon tapewounds so they do not ground out when playing. I have to keep my palm on bridge to eliminate hum. Playing through an aguillar tone hammer 500/ sl 112 cab. Any ideas???