According to my practical tests about inductor cores at 200khz switching of which is my best preference for class d amplifier, i noticed too much noise at (music pause) using a phone as audio source charger plugged in then thru a mixer to my class d prototype using sg3525 as signal generator & ir2110 & buffers as fets drivers. There's too much noise using t130-2 core carbonyl than when i changed to a blue aph33p60. Infact this blue core is absolutely quiet. Some things are better done practically than reading theories to actualize outcomes.
