I have an audio signal coming out from an iPhone which I would like to record in iPad using its mic input.

I have tried this with simple resistor divider (and TRS-TRRS connectors), but it seems to worsen the sound quality.

How can I do this without worsening the sound quality ? Are there any off the shelf components I could use to achieve this ?

I came across this adaptor, but it says 50dB loss, I guess my sound quality would drop, which is not great for my application.

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    \$\begingroup\$ 50dB loss refers to a decrease in signal amplitude .... it does not refer to signal distortion \$\endgroup\$ – jsotola Sep 27 '18 at 1:34
  • \$\begingroup\$ "but it seems to worsen the sound quality.", where is your proof to back that up? - "I guess my sound quality would drop", that's a non-logical assumption you've made, unless you... again, have proof, or no proof. \$\endgroup\$ – Harry Svensson Sep 27 '18 at 2:59

You need to add an AC coupling capacitor before your signal goes into the iPad. I'm thinking that about 30dB attenuation should get you in the ballpark level-wise.

Also be careful of the TRRS pinout both coming out of the iPhone and going into the iPad. Check online sources for the pinout - my recollection is that Apple does things differently from anybody else.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ "my recollection is that Apple does things differently from anybody else." - Sadly and annoyingly true. \$\endgroup\$ – Harry Svensson Sep 27 '18 at 2:26
  • \$\begingroup\$ Make sure you pick a CLEAN GROUND for the bottom connection to R2. \$\endgroup\$ – analogsystemsrf Sep 27 '18 at 4:01
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    \$\begingroup\$ Both ground connections come from the TRRS plugs used for the two devices. That's as clean as it gets. \$\endgroup\$ – Dwayne Reid Sep 27 '18 at 4:53
  • \$\begingroup\$ @Dwayne Reid, When I use a capacitor as shown in your circuit iPad doesn't detect the mic. I believe this is because iPad requires a DC signal for the mic to be recognised. \$\endgroup\$ – Pravi Sep 27 '18 at 11:20
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    \$\begingroup\$ Please let me know if that works for you and I'll modify my answer for the next person who is trying to do what you are doing. \$\endgroup\$ – Dwayne Reid Sep 27 '18 at 16:24

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