SPC Video #005-Recording Cockpit Audio

Okay everyone.  I’m finally releasing a quick video covering how I record cockpit audio.  This is my most frequently asked question.  The video does not tell the whole story, so I’m doing that here on the website as well in this post.  I may make it a permanent feature on the site as well.

So take a look at the video, but here are some more details.  The first thing to understand is that what you record to doesn’t really matter.  I use a digital audio recorder, but recording to a video camera, an mp3 player, or even an old fashioned tape recorder is the same thing.  The trick is getting the audio from the plane to a level that can be recorded by one of these devices correctly.

The Levels.  Whatever your method of recording, you will likely be using the Microphone (Mic) input jack of some sort of recorder.  The levels that a Microphone puts out are much lower than the levels that are needed to drive headset speakers, which is why just plugging a headphone output directly into the Mic input on a recorder will likely not work well.  The audio will be overdriven and garbled.  So, the first issue is to reduce the levels coming out of the plane’s audio system to a mic level that can be recorded.  There are several ways to do this, but we’ll get to that in a moment.

The Jacks:  The other issue is much more straightforward; you have to use adapters and cables that allow the different jacks for headsets and recording devices to be connected.  This is a simple physical plug problem which can be addressed with various adapters.

The Solutions:  There are probably many more ways to do this, and I welcome comments from readers/listeners for more ideas, but I’ll likely cover most of the common ways to accomplish the same thing; record audio in the cockpit.  Here are various solutions in no particular order.  I will list pros and cons for each solution.

• Probably the simplest and least expensive solution from an equipment perspective is to use a simple attenuating cable that can be found at many audio and electronic parts stores, including Radio Shack, like this one.  This type of cable is special because it has electronics built in that will “attenuate” the higher speaker audio signal coming out of the plane down to a lower signal suitable for recording from a Mic input on your recording device.  The one I’ve linked here attenuates 90 dB if I remember correctly, which is about right for this application.  Notice also that the cable is a mono 1/8 inch male to mono 1/8 inch male plug.  That means you’ll have to buy adapters to match the output and inputs that you’ll need.  In most situations, that will be a 1/4 inch male (stero or mono depending on your plane’s audio panel…mono being safest) to 1/8 inch mono female adapter.  The 1/4 male plug would plug into an unused headset port in the plane.  Pros: Cheap, simple, parts likely locally obtained. Cons: Requires an unused headset port in the plane (i.e. in a four seat airplane, you can’t have 4 people with headsets plugged in), doesn’t record ambient noise.
• Another solution would be to build on the attenuating cable solution into a pass-through attenuating cable.  Using the solution above you can add additional adapters and cables to allow the contraption to pass through the audio while attenuating and splitting the audio to a recording device.  This would necessitate some additional splitters and adapters that can likely be found at local or online parts retailers such as Radio Shack and PartsExpress so that you would split off the audio from the airplane’s audio panel into two paths, attenuate the one to the recorder, and pass through the one to the headset.  This would allow a jack that is in use by a passenger to be used to record as well.  I have not used this setup myself.  Pros: Parts likely locally obtained, can use an in-use jack and works with any headset.  Cons: Solution getting complicated with many wires, adapters, etc., doesn’t record ambient noise, and is starting to get expensive with all of the adapters.
• The purpose-built patch cable solution is probably the most simple and the hardest to screw up.  It is not necessarily the cheapest of the solutions, but isn’t too expensive.  This is the solution that I have used for the vast majority of my recordings.  I have chosen this because it is simple, reduces clutter in the cockpit (least amount of wires), and reduces the likelihood of missing audio because of batteries, wires coming unplugged, etc.  This solution simply involves purchasing a purpose built cable for recording in cockpits and plugging it in between the audio panel plug and your headset.  This solution works with virtually any standard airplane and any headset, and is the solution outlined first in the accompanying video.  It is essentially a pass through attenuating cable that is packaged into a small and simple cable.  Various versions of this type of cable can be purchased through aviation audio specific resellers and manufacturers, including Marv Golden, Barnstormer Audio, Aircraft Spruce, and probably others.  I personally use the one from Barnstormer, but they all do the same thing, and will likely cost somewhere between $30 and $40.  Pros: Simple and foolproof, can use an in-use jack and works with any headset.  Cons:  More expensive, doesn’t record ambient noise.
• A lavalier microphone (lav mic) solution can be used as well.  This is a more organic solution for recording the audio in the cockpit because it doesn’t interface with the airplanes audio system directly.  I touch on this near the end of the accompanying video, and I have used this method personally with success a few times.  You simply use a lav mic that can be obtained from many places, including this one from Radio Shack, and you simply plug it into your recording device and put the small microphone into an ear cup of your headset.  Electret type microphones will give better results, but require batteries.  You’ll need to play with the levels a bit to get it right, but this method does work, and will record some ambient noise as well…something many people desire.  It is more like the sound of actually being there, but does require having extra wires dangling from your headset and of course does not work with in ear headsets such as the Clarity Aloft.  Pros:  More organic sound recording, doesn’t use an audio jack in the airplane, relatively inexpensive (especially if you already have a lav mic or another need for one).  Cons:  Works only with “over the ear” headsets (most of them), increases clutter and wires in the cockpit, could require additional batterries in the mic, could be uncomfortable with some headsets.
• The poor-mans lav mic solution is simply a variation of the lavalier microphone solution outlined above.  Everything is exactly the same, but instead of using a real lav mic, some people have had success using a set of cheap earbud style headphones (like those that come with an iPod for example) as a microphone.  Simply stick the earpieces in your headsets earcups and the other end into the mic jack of your recording device, play with the levels, and cross your fingers.  I have actually tried this for giggles, and it does work, but the levels and sound quality are nowhere near that of a good electret microphone, or one of the other solutions listed here.  With the right combination of earbuds and recording device (with various levels of input), there is nothing wrong with this, but you will have to experiment a little.  Once you find a combination and settings that work, it shouldn’t be a problem and should produce results similar to the lav mic solution above, but do your testing.  Pros and Cons are the same as above besides the extra testing mentioned here. 

Okay…there’s the rundown.  For what I personally do, as I mentioned, most of the time a use the Barnstormer purpose-built cable for audio.  As I record video, though, I’m trying different things, including splitting the audio coming from the cable to my audio recording device AND the video camera, or using the splitter cable for the audio only device, and using the lav mic solution for the video camera.  This gives me the best of both worlds as far as audio goes (more organic audio with the video and more pristine audio with my audio recorder).  This is an especially useful scenario if I have a passenger who is willing to put the lav mic in their earcup, that way it keeps the extra cable away from me and reduces the chance of it interfering with my PIC duties.  The Barnstormer cable and other solutions like it are absolutely bullet-proof…I’ve never had a failure or forgotten anything, etc.  There are no batteries to change, no extra cables into my earcups to deal with, etc.  I just leave the splitter cable attached to my headset and carry it in my headset bag as if it were part of the headset.  Works out well.

Hopefully this post and video answers this question for everyone.  I’ve tried to be as comprehensive as I could, but I’ve missed anything or made any mistakes, please let me know through the comments (so others can see as well).  Happy flying (and recording).  Can’t wait to hear everyone’s cockpit audio.

SPC Video #005-Recording Cockpit Audio from Bill Williams on Vimeo.

Podcast: Play in new window | Download (41.1MB)

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