audio input to samsung S4

[lechat]

bit of a tech sort of question for anyone who is capable.
I'm trying to get sound from a digital piano to the audio recorder of my phone so I can get a clearer recording to go with the video. I think what I want to do is use RCA line out to 3.5mm aux and just plug that into the phone.

I've managed to output the audio to an amp via a 6.5mm (1/4 inch) aux cable and it plays fine but whichever of my billion audio cables I try I can't seem to get anything to the phone so I'm thinking maybe this.
http://www.ebay.com.au/itm/331560135819
I can't seem to wrap my head around all this trrs shit so if anyone can point me to a 2m cable which is plug and play it would be much appreciated.

 

[SnowyGamester]

Your existing cables don't work because they're only designed for transmitting stereo audio but the 3.5mm port on most phones nowadays allow for simultaneous stereo output and mono input, the problem being that the contact point for the input is separate from the two output connections (diagram [http://www.cablechick.com.au/resources/image/trrs-diagram2.jpg]). Ideally you want an adapter like this [http://www.ebay.com/itm/161825576934] that will separate the input and output into separate standard jacks. The adapter you listed could work if you ran the audio input through the video jack however there are a few different wiring standards for those type of connectors so it's difficult to be sure if the grounding connection would be in the right place for it to work.

 

[Albino Boo]

You need a 4 pole 3.5mm jack to work with the phone. You can get RCA to 3.5mm 4 pole cables. There could be another issue of impedance not being matched causing the sound clip. If that happens you best bet is get a 3.5mm 4 pole to stereo 3.5 jack converter and plug it into the headphones output of your piano. Then just plug in a 3.5mm 4 pole male to male cable in.