As what the title says When I connect my designed preamplifier,which is in a breadboard, unto a power amp kit (Acoustic 50W Mono) with a speaker, there is a farting sound, as if it is a pulsating DC. And if I directly connect my music or mic to the power amp the output of the speaker is fine but very weak since there is no preamp.
In addition, the farting sound is always present, meaning with or without an input of music or mic the farting sound is there.
From what I could think of right now is that it is due to the bias also going to the poweramp or too much low frequency that I'm not aware. And I need help in solving this problem.