enter image description hereI am not an audio engineer, but rather for my company we are in a situation where we need the following customer variables met:

Multiple customer locations have variations of mixing decks and speakers that in turn have variations of output types. i.e. RCA and 1/4 and XLR / any other output a deck might offer.

What I am trying to do is patch the output from any one of these sources (dependant on what that location has) into a mobile phone 3.5mm jack so that I can make a call and have the output from the source act as the microphone-in - effectively relaying the audio from the source to the listener on the other end of the call.

What I have so far:

RCA L+R male to 3.5mm male TRS Mic / Headphone splitter of 2x female 3.5mm to 1x male 3.5mm TRRS 1/8 Stereo male to 3.5mm (TRS?) male adaptor. TRRS to TRS Inverter (ensuring both android and iPhone compatibility)

Could anyone please offer advice on which cables would fulfil my requirement of multiple sources?

Is there anything I need to be aware of on the deck?

Thanks so much!

Edit: Uploaded image: IS there something like this?

2 Answers 2


This is going to be fraught with problems. Microphone inputs on cellphones are likely to have some amount of detection logic to try to determine what kind of device is connected. You can't be sure of the cellphone's reaction if you plug something else in.

Your best chance of making this work involves a transformer, in order to deal with signal unbalancing and ground isolation. You will also need level reduction, preferably by having a step-down transformer, i.e. 4:1 or more, because the cellphone will amplify the incoming signal, and the amplifier will almost certainly be overdriven by normal signal levels. You will also need a capacitor for blocking the bias voltage that the cellphone feeds to the microphone.

This sort of thing is very unlikely to be available ready-made. It is a DIY job that will require some amount of expertise.

  • Have uploaded image into question for clarity - do you know of an adaptor that might perform the above without regards to adjusting the amplification?
    – leo_cape
    Commented Jun 26, 2017 at 0:45
  • No. I guess you would have to build this yourself. The 4-way plugs are available from a good parts distributor, but finding a suitable transformer might be a bit harder.
    – sh-
    Commented Jun 28, 2017 at 10:50

This sounds like a nightmare, I agree with Sh- nothing like this will exist you will have to make it yourself. You are also going to need to know what output level these devices you are connecting to have(mic, line, consumer) and build pads for them.

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