I recently went through my pedal board on a quest to find pedals that were causing excess noise. I run a strat through a cranked jcm800 so any noise early in the chain becomes really prominent. I noticed that my two hartman pedals, an 8va octafuzz clone and a rangemaster treblebooster both inject a low hum into my signal when the pedals are DISENGAGED. The hartman pedals run on batteries, so they dont share a power supply with all of my other pedals that run on a pedal power 2. Any ideas what could cause this?