Hey folks,
i need your help here!
i am building a mic preamp (based on hamptone FET). my preamp is 2 "gain stages":
Tranny->Stage1->Pot (Voltage divider) - > Stage 2 -> Pot (voltage divider) -> Line driver (IC)
1. when no mic is conneted i get crazy oscilations.
2. when mic is connectedm i get high pitch "squeeling" background noise. that "squeeling" noise changes pitch and level when i touch the body of the knobs, as well as changing pitch when rotating the knob.
i used a star ground (See pictures). and placed 470uF and 1000uF capacitors between the +16 and gnd.. grounding the body of the pot's isnt helping. it sounds like some ground loop, but how is that possible?
i need your help here!
i am building a mic preamp (based on hamptone FET). my preamp is 2 "gain stages":
Tranny->Stage1->Pot (Voltage divider) - > Stage 2 -> Pot (voltage divider) -> Line driver (IC)
1. when no mic is conneted i get crazy oscilations.
2. when mic is connectedm i get high pitch "squeeling" background noise. that "squeeling" noise changes pitch and level when i touch the body of the knobs, as well as changing pitch when rotating the knob.
i used a star ground (See pictures). and placed 470uF and 1000uF capacitors between the +16 and gnd.. grounding the body of the pot's isnt helping. it sounds like some ground loop, but how is that possible?