Cockpit Audio and Patch Cables

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Addicted2climbing

Pre-takeoff checklist
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Addicted2climbing
Hello All,

I have done a search on this in POA and found a good deal of info, but not exactly what I am looking for.

Since I have been working with recording my own videos with an externaly mounted gopro I also wanted to get my COM audio track recorded as well. I know I can buy a patch cord and connect it between my headset and the plane, or possibly just connect it to an unused passenger imput. However, my question is I have the Bose A20 Bluetooth and there is an AUX audio in and curious if that could be used to record audio.. But if it is IN only I doubt it. Any possibility of connecting my phone with the buetooth as if I was going to make a call and just use it to record audio?

Or back to basics and I make a patch cable. I have read that people say they made their own and installed a resistor to bring the levels down. Anybody have a schematic so I can make one? Chances are Ill just connect it to my Iphone on a passenger Com line..

Best regards,

Marc
 
Mike I said:
No chance with the Bose AUX jack.

Make your own with the following:
http://www.radioshack.com/product/index.jsp?productId=2062456
http://www.radioshack.com/product/index.jsp?productId=2103841 (brings levels down)

That's all you need.
Click to expand...


That attenuated cable may not be enough attenuation depending on the recorder being used. Those are typically for a fixed line level output. Plugging into the panel will have higher voltage output and vary based on volume setting on radio.

You could build something easily if you have basic electronic abilities ( as it seems you do if asking for a schematic) with a variable resistor with the right tolerances.

Something like this may give you more flexibility to fine tune the audio if you are getting distortion .. but would have to convert from stereo to mono with a TRS to a TR adapter.

http://www.radioshack.com/product/index.jsp?productId=2102975
 
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Hey Guys,

Thanks for the quick reply.. I am more then capable to solder up a cable if there is a schematic to follow. Using a variable resistor is fine if needed. I am sure I can also adjust the levels in Post so long as they are not distorted due to being maxed out on the recording.

The Radio Shack version is about as easy as it gets with just a plug swap.. However if its not ideal then I am totaly fine making my own with whatever is required...

Also I know I can do the mic in the earcup, but I think I want to avoid that..

Marc
 
Don't knock the mic in earcup. It gets the feel of the background noise that is lost with an intercom-only feed. The only problem is, it's hard to control levels of good vs bad audio.

When I get back to doing video, the cameras will record "raw" audio. The Tascam DR-07 will be hooked to the intercom via a 20dB attenuating cable. And the intercom and raw cockpit audio will be merged in post-production into something that both has high-quality voice comms as well as some level (reduced) of background raw audio.

Anything else does not end up "feeling" right.

The Tascam and various other recorders have built in ALC. ALC can be used for good or evil but generally since we're setting levels to our own ears in the intercom, setting a generally good level at the recorder and then activating ALC as a form of "anti-clipping" has worked well for me on a few test recordings. ALC can also salvage a total screwup on setting levels if you really mess up. Won't sound good but it's better than overdriving the recorder into clipping and nastiness that's not even usable.
 
Hey DenverPilot,

I just looked at the Tascam unit and it looks really nice. I will give it consideration. However the Iphone app I plan to use may have ALC as well. I will have to look.

I know the earcup method sounds more organinc and normal, but I was trying to avoid another wire attached to me. I suppose I could just zip tie it to the cord for better cable management. Would an in ear microphone have any problems with the ANR from the bose?

On the tascam, is it possible to use both the wired mic and the onboard mike. Maybe the onboard could get the engine sounds with a very low sensitivity level.. I am concerned the engine sounds from the in ear mic may sound odd from the ANR..

Marc
 
Negative. On the Tascam it's internal or external audio, never both. It's a menu setting actually not the usual "when a plug is inserted the audio is taken from the line input" of cheaper recorders.

M-Audio also makes some nice recorders with similar features for slightly lower prices. I have some M-Audio studio input (XLR or 1/4" Instrument inputs) to FireWire converter gear that works well on both Windows and OSX. (Heard that it works in Linux too, but haven't tried or tested.)
 
Addicted2climbing said:
Hey Guys,

Thanks for the quick reply.. I am more then capable to solder up a cable if there is a schematic to follow. Using a variable resistor is fine if needed. I am sure I can also adjust the levels in Post so long as they are not distorted due to being maxed out on the recording.

The Radio Shack version is about as easy as it gets with just a plug swap.. However if its not ideal then I am totaly fine making my own with whatever is required...

Also I know I can do the mic in the earcup, but I think I want to avoid that..

Marc
Click to expand...


Adjusting the levels post will work to a point, but if it is over driving on the initial recording , you will just lower the total over driven volume..... If that makes sense.
 
denverpilot said:
Negative. On the Tascam it's internal or external audio, never both. It's a menu setting actually not the usual "when a plug is inserted the audio is taken from the line input" of cheaper recorders.

M-Audio also makes some nice recorders with similar features for slightly lower prices. I have some M-Audio studio input (XLR or 1/4" Instrument inputs) to FireWire converter gear that works well on both Windows and OSX. (Heard that it works in Linux too, but haven't tried or tested.)
Click to expand...


Do they have some sort of visual metering you can see the peaks to made adjustments with initial recording?
 
I used the Radio Shack attenuating cable, routed it into the audio-in jack on a Canon digital video recorder, and it worked very well. Clean audio, no clipping.

Ymmv.
 
I tried the attenuating cable with my iPhone, it didn't work. I believe the iPhone expects to see a certain impedance.
Addicted2climbing said:
Or back to basics and I make a patch cable. I have read that people say they made their own and installed a resistor to bring the levels down. Anybody have a schematic so I can make one? Chances are Ill just connect it to my Iphone on a passenger Com line..
Click to expand...
 
Try using a spare headset. Mount the mic between the cups and tape them together. You can adjust the seal to get the desired "ambiance"
 
The attenuating cable works great with a GoPro. It over-attenuates just a bit, so I have to pull the levels up slightly, but it definitely doesn't clip. I think the RS cable is about a -60dB attenuator, and -40dB is desired...but it works and it's cheap. Can't speak to using it with an iPhone though.
 
cavmedic said:
Do they have some sort of visual metering you can see the peaks to made adjustments with initial recording?
Click to expand...

The Tascam does. I think some others also. Not all.

Typically the cheap digital recorders meant for dictation and college students don't. Ones built specifically to capture audio for project work, do.
 
I used a 4 conductor TRRS and an attenuator, still no joy.
 
I went to radio shack and bought both options (the mic in the earcup and the mono to mono 1/4" Y-Splitter plus a 1/4" to 1/8" cable).

One was almost $40, and the two little adapters only $4 - $6 each. They worked! I plugged the 1/8" into an "aux in / mic in" on a handheld sony audio voice recorder that I wore around my neck on a lanyard I made.

Lots of cords and it ran out of space (bummer, he was a good CFI and I wanted to replay the lesson in my car)..... but.... it worked!

I am totally recording my flights from now on (audio).

Video I just hand a passenger my cell phone and show them how to record a short HD video.
 
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