This is a Yamaha compressor. There are no particular operational issues, but please consider that it is old. In my subjective opinion, there is no noticeable crackling, and the operation is good. YAMAHA CO-10M II compressor effector. Equipped with three controls: OUT LEVEL, ATTACK, and SUSTAIN. - Brand: YAMAHA - Model: CO-10M II - Function: Compressor - Controls: OUT LEVEL, ATTACK, SUSTAIN - Power: DC IN 9V - Input/Output Terminals: IN 4, OUT Thank you for viewing. Type: Electric Guitar