Recording Aircraft Intercom
I know its been discussed quite a bit but there's nothing that specifically answers my questions. I have a sony px 470 voice recorder which i am planning to plug into the spare output on the passenger seat in order to record intercom audio in a PA28. Previously, i have tried the sony px240 and initially i thought it would be fine because i ran a test recording pre-flight and it sounded okay apart from a slight whining in the background. After my flight i listened back to the recording and from when the engine had started the whining was very loud and increased in pitch as RPM increased and voice was slightly overdriven. After a bit of research i have found out that overdriven audio is because i was using mic-in instead of line in/ audio in, but nothing to explain the whining (my guess is alternator or something). Since then, i have now purchased the px 470 because it has an option in the settings to change external devices to audio in instead of mic in. Here are my questions:
Is 'line in' and 'audio in' the same?
Would the whining effect be eliminated with Audio/line in input?
Has anybody had any experience with this?
I am aware that you can place a small mic inside the headset (which will be my next option if this fails), but i would prefer to have something out of the way. Also, i am aware that there are certain laws regarding ATC transmissions etc, this is purely for personal use so don't worry!
I know its a bit of a techy question so i appreciate any advice or knowledge!
Thanks
Matt