Is cable capacitance the reason why my amp will run happily with the 10' headphone cord plugged directly in, but when I plug in a 15' extension too it complains with loud buzzing? The loud buzzing only happens throughout about half of the volume range.
Top Mall-Fi poster. The T in META42. Formerly with Tangentsoft Parts Store
Sep 27, 2001
Originally Posted by kin0kin I was not aware that the capacitance of the cables is almost around 500pF
Yes, I've seen this myself. It's one reason high-power op-amps are so popular for audio: they're often made to have high output currents precisely so they can drive heavy capacitive loads easily.
By the way, your "at 20 kHz" qualifier above isn't necessary. The capacitance is the capacitance. Changing the frequency you measure at only makes your measurement job harder, since it's easier to test capacitance at higher frequencies. You can talk about the impedance at a particular frequency, but that's a separate issue.