Normal behavior for a high impedance input with 20 meters of unterminated cable connected to it.Hi there, hoping someone with better skills can help me please.
I have a long 25 meter RCA (budget one, no shielding) running to the SAT input on my old Pioneer AX10Ai AV Receiver.
It works but is noisy when unconnected at the far end.
The line is to allow a small mixer and guitar to be used outside.
Strangely when the mixer and reverb unit is connected to the RCA wall plate, and tested with a microphone, the noise goes! And the input to Pioneer and output to garden Evid speakers is perfect .... no noise, no hum, no loss. Good but odd.
The RCA is housed in a waterproof wall enclosure. It feeds into metal trunking in which there is data, power and indeed irrigation pipes and then back to the house. The cable itself is an Amazon cheapo.
Wandering if it's earthing? And if it is, is there anything I can do about it?
As I say when connected it works very nicely, but when unconnected at the far end it's hums away quite badly.
Would very much appreciate any help you might have. Many thanks in advance
You could make a shorting plug or a plug with a 100 ohm (or less) resistor from the pin to the shell that you plug in to the end of the cable when the mixer is not plugged in. That will solve the issue.