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Today I met with a vendor regarding the installation of a PA system at our facility. We currently record meetings with a handheld camcorder mounted on a tripod, and we're looking to add microphones in order to feed a clearer signal into the camcorder's audio-in jack directly from the mixer board.

This guy is supposed to know audio equipment, and at first he seemed knowledgeable until he made one statement that left me confused: he said that if we input an audio signal that is too high into our camcorder, the camcorder will stop recording video (i.e. the video will be either distorted or blanked out) until the audio levels are correctly adjusted.

Short of actually zapping circuitry inside the camera with an exceedingly high voltage and causing it to stop working, what on Earth is he talking about??? How could a high audio level affect the recorded video feed in any way?

Note also that he had no idea which camcorder we use because I never told or showed it to him. He was speaking in generic terms and applying this statement to all camcorders.

After he said this, I started seriously questioning if anything else he'd said could be taken seriously.

Any light to be shed on this?

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  • \$\begingroup\$ It is possible that your intuition about zapping the camera with a high voltage is the right track. If the source has a high enough voltage it could go through protection diodes without exceeding maximum IC specifications, but leading to all kinds of temporary problems. \$\endgroup\$
    – Edgar Brown
    Commented Nov 6, 2018 at 0:56
  • \$\begingroup\$ This sounds like a problem that would occur with analog cameras and one that could potentially happen with digital cameras. To be sure it wouldn't happen, one would need to test with the specific camera in question. This sounds like something he does as a best practice, because it is simpler/easier to prevent the problem for every camera than it is to troubleshoot individual cameras. I would note that if you're using a separately powered mixer board to output to ANY low power audio input(camcorder or not), take into account that you could damage the connected equipment by overpower. \$\endgroup\$
    – K H
    Commented Nov 6, 2018 at 1:00
  • \$\begingroup\$ Some professional sound boards can output a differential 20 volts P-P into a 600 ohm load. If a mic input is expecting a old standard +/- 1 volt P-P this higher voltage could damage the mic pre-amp and leak into the power feed to other IC's. Some to watch out for. \$\endgroup\$
    – user105652
    Commented Nov 6, 2018 at 1:04
  • \$\begingroup\$ He was almost certainly not referring to permanent damage to the camcorder because he implied that adjustments to the level would restore the image. Also I'm confident he knew the difference between 1vpp and 20vpp. \$\endgroup\$
    – Ryan Griggs
    Commented Nov 6, 2018 at 3:08

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The only thing I can imagine is that this guy had a bad experience a long time ago with an analog tape based camcorder. I could conceive of a situation in which a badly-designed unit would allow an excessively hot signal from the audio track to bleed over into the adjacent sync track. Any decent unit would have been designed to limit the audio level before this could possibly happen.

I assume your modern camcorder is both digital and uses solid-state storage. In which case, there is no possible way for the audio signal to affect the video (or vice-versa).

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  • \$\begingroup\$ Thanks for your answer. Yes our camcorder is a brand new Sony which records to a SD card. So I wonder how credible this guy is? or is he living in the past? :) \$\endgroup\$
    – Ryan Griggs
    Commented Nov 6, 2018 at 15:37
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    \$\begingroup\$ It's hard to say. If he works for the vendor, one would hope that he's at least up to date on their gear. And it would be in the vendor's interest to make sure he's aware of how their gear interfaces to (modern) external equipment. But yeah, it sounds like his knowledge is a bit dated. \$\endgroup\$
    – Dave Tweed
    Commented Nov 6, 2018 at 15:43

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