Headphone amplifier for Camera without audio jack

Question

I am thinking about a project for my camera. A problem that often occurs with cameras and I haven't found a solution yet is, that there is an external microphone input but no audio output to monitor the sound.

Could I "split" the signal that comes from the microphone and feed it into the camera but also to an audio amplifier like this: amplifier

Would this reduce the quality of the recorded audio? Also can I safely use any headphones on such an amp (like the ones that come with Apple products)?

Answer 1

If the amplifier has a high input impedance, running the signal from the microphone to both the camera and the amplifier, e.g., through a Y-connection cable, should not noticeably degrade the signal.

That said, here are some caveats.

• Realize that you are monitoring the signal from the mic, not the actual recording. Though this would give a relative perception of echoes, location background noise, etc., it would not show issues during recording such as excessive compression, electronic noise in the camera, distortion due to high amplitude, etc.
• The amplifier you suggest is class D, which is more efficient than linear amplification, but it uses high-speed digital switching. If some of the switching transients were to leak into the camera sound input, it might affect the audio quality... or might not. If you're just driving low-power headphones, think about using lower-power linear preamplifier.
• Be careful to avoid damage to the camera or introducing hum due to power supply issues. Perhaps run the preamp from a separate battery.