Using a smartphone to record live audio and/or video

This is a tutorial on how to use a smartphone (or cell phone) to record any performance for which the phone’s microphone is inappropriate (as is the case with DJs, live electronic music, or really anything that is amplified). You may have tried this before & found that the result is an unintelligible noise, this happens because there is no gain control between your source & the recording, as there would be with a multitrack or other professional recording system. To circumnavigate this problem you will need a few things…

Things you will need:

• A smartphone or cellphone or even an iPod. The important part here is that 2 requirements are met:

1. The device must have a 3.5mm jack (a headphone jack) that accepts a pair of headphones with an inline mic (a hands-free wired headset). The reason for this is that a standard pair pf headphones has 3 contacts on the plug while a hands-free headset has 4. The extra contact routes back into the phone.
2. Your device must also have the capability to record from the mic input. This sounds obvious, but there is often no way to know whether this will work without trying it.

• A 3.5mm Plug (4 Pole) To 3 RCA A/V Cable.
  
• A suitable cable to connect one of the RCAs to your source. The most common connection I see is 1/4″, so a 1/4″ to RCA cable will do in that case.
• Adapters to plug it all in together. This is an optional accessory depending on the cables you have. If the 1/4 to RCA or the 3.5mm to RCA A/V cable has female RCA connections you will not need the adapters  otherwise you will need a female to female RCA coupler (most commonly available at Radio Shack or any home theater distributor) to link the two cables together.
• An audio source. Ideally this will be a mixer that has a record out or booth out if you are recording a DJ or, if you are recording a band (etc), you will pull your source from the front of house mixer.
• Something to hold your phone to record the video. This seemed pretty obvious & self explanatory, but it is a DIY tutorial, so there. I actually saw a retailer recently that was offering small brackets meant to hold an iPhone for video recording (which even had tripod threads on it).

The procedure:

The procedure is quite simple, you only need to connect the source to the RCA that connects to the contact normally used for the microphone in a hands-free headset (which I believe is the yellow if you have a standard color coded A/V cable like the one shown above), the other RCA connections will only output sound & not accept an input, so this will only produce a monaural recording, but most phone’s video software doesn’t record stereo anyway. For this reason, if possible, you will want to connect to an output that combines the two channels into one signal stream (not possible with most DJ mixers, but possible with some FOH mixers).

A few notes:

• Connecting this apparatus is an exact science, the recording itself is not. When I say that I simply mean that you will need a bit of trial and error to get the levels right. When in doubt, record a few seconds and listen to it before your friend, the headliner, whoever, plays their set. This is not something you will get quality audio out of if you are in a hurry (unless you are incredibly lucky or know the mixer’s output levels well and have recorded it this way before), the reason for that is you will (typically) not have a meter for the audio levels coming into the phone so you won’t know if the output of the mixer is coming in too hot without a bit of testing.
• The RCAs on the cable you end up using for this may not be color coded the same (or the pinout may not match the standard if you scrounged a cable that came with someone’s camcorder) so test that as well before you need this to work for you.
• When in doubt about the recording levels, run it lower than you think you will need. This a basic concept to studio engineers, but it may not be as obvious to someone who hasn’t done it a lot. The reason for this is that once you clip a signal the sound is completely lost, whereas if your signal is a bit too quiet you can always amplify it in post-processing.
• While it is possible to span long distances with an RCA cable added into the middle of the connections, it is not advisable. The more adapters & connections used reduce the signal quality of the final recording & for that reason the shorter the distance the sound has to travel in the cable the better it will sound.
• While it makes more sense to plug this apparatus into the venue’s mixing board if you are recording several different artists who are running separate inputs, it may be much easier to do this using the booth out connectors on the DJ mixer (assuming they aren’t in use) if everything is running through that mixer.
• This entire article can be applied to recording with a laptop as well as long as it has a line in or mic connector (if it is a dedicated mic port & cannot be switched to a line level input remember that a mic is amplified more than a line level input).