i have the original big box holy grail and i had a lot of problems with humming and buzzing coming from the pedal.

when the pedal was in my amps effect loop (marshall avt150H) it sounded fantastic but there was constant hum coming from it, so i thought id put it back in the front of my amp, but the humming stopped and the buzzing got worse. so i took it out and put it back in the effects loop and now i had buzzing, humming, farting, squeling, everything you dont want from a pedal.

so i asked a few people on here and various other sites, and few people said a few different things, and i eventually found out i was overloading the power supply. i used the original power supply that came with the pedal, but the extension cables i was using etc, couldnt handle the power and what not, and for some reason it just took the holy grail and buzzed that, none of my other pedals had this problem, just the holy grail, it was also worse in my fender hot rod deluxe, but i had some problems with that amp, and thats another story. but yh just check the power and make sure your not overloading the pedal, try it on its own, and see what happens

anything else you need help with just ask here, and we’ll hopefully sort it out !!!