Posted by Mark Robinson on 11/30/05 01:11

Rob J wrote:
> These miniDV camcorders have an input for an external (stereo) mic. That
> is the input to use if you want to drive it from an external sound
> source while recording onto tape in camera mode.
>
> I have tried this a couple of times, using a computer audio cable
> plugged into the external mic jack, but the sound was ruined by a very
> loud hum.
>
> As the camcorder was running off its own battery in one case, it could
> not be an audio hum loop, and the source device was not producing the
> hum.
>
> Any ideas?

With no knowledge of this device:

A loud hum could be caused by a broken earth wire in the microphone lead, or by
the connections being reversed at the plug end.

Some microphone inputs supply a voltage to power the microphone. If your
microphone doesn't require this (if it's dynamic rather than electret) putting
a capacitor of say 1uF in the signal leads should stop current flowing out of
the input through your microphone. Messing around with a multimeter and a plug
in the microphone input socket should give you some clues. Also, you should be
able to make each channel hum in turn by touching the tip and ring contacts
with something metallic and ungrounded. That would prove that it's a stereo input.

Many microphone inputs are mono only. What does the user manual say about the
microphone input ?

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