i have this peavey blazer 158 for 1992, and it sounds better then my marshall mg30dfx. any way i found it downstairs and just started playing it right. well it makes a big sound some times like errrrrereeeeeeeeeeer!!!!! when i go to reverb and it makes poping noises even if it's a one when i play chords. any help on whats wrong with it?

sry for crap description, if you need more just ask and i will try to write more if i can.