Does the hot shoe microphone adapter interfere with the sound?

[TapDaddy]

I have a Canon Rebel T3i and I put a microphone holder on to my hot shoe (the adapter is metal) and after this my microphone won't work when plugged in to the body. Is the metal interfering with it? When I unplug the microphone from the hot shoe the audio is back but if I put just the hot shoe on and the microphone off, the microphone won't work again! Can anyone help?

[Skirball]

It's certainly a reasonable assumption.  If the holder is connecting with any of the contacts on the hotshoe you could get any sort of grounding loop with the microphone.  Try putting a piece of electrical tape over the contacts and see if that works.

[TCampbell]

Specifically which microphone and holder are you using?

The Rode "VideoMic" series is very popular, but the mounting bracket is designed to work in the hot-shoe and does not conduct any signals into the microphone -- but that's their brand.  I don't know what brand/model you are using.

The rails on the camera hot-shoe serve as the ground pin and of course the small round contacts are actually live when the camera is powered on.  If for some reason you have a microphone and/or hot-shoe bracket which is metal and actually conducting those pins through to the mic... then I could certainly see it interfering.  But as ALL cameras using those rails as the ground pin (that is an industry standard -- not just something unique to Canon) then it would not be a good microphone mount design.

[Skirball]

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@TCampbell wrote:
But as ALL cameras using those rails as the ground pin (that is an industry standard -- not just something unique to Canon) then it would not be a good microphone mount design.

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That's what I was thinking. 

If the mic was poorly designed, or maybe just has a short, the common line might be conducting through the metal chassis of the mic, which in turn is conducting through the metal stand and thus grounding on the hotshoe rails.

Regardless, if it works until you plug it into the holder, and works again when you take it out, it's a safe bet it's the holder/mic causing the issue.