Problems recording audio using Rode Videomic
 

I have just purchased a Rode Videomic to moutn on top of my 7d. However, on the first few tests I am noticing a huge amount of hiss in the background. I've researched this problem on the web and notice that it seems a relatively common problme particularly when this is no/little audio and the 7d tries to compensate for this by boosting the audio signal (cusing it to amplify 'ambient' sounds in the room).

What workaround do people use to combat this as it's extremely frustrating for interviews when there will naturally be breaks in speech and I don't want to have to edit all the audio after the event.

Welcome to the 7D. Untill we either get a firmware fix disabling the AGC or Magic Lantern, your on camera options are limited. I purchased the Beachtex DXA-5D which inputs an inaudible tone to keep the AGC from boosting up, JuicedLink also has something simular. You still get noise but it is much better. Your other option is dual sound with something like a Zoom H4n.

Unfourtuantly, all these options are over $300 :(

Ok, thanks. What I'm finding odd is there are plenty of videos up on youtube/vimeo with people using the Rode Videomic with the 7d and there is no hiss in their videos or mention of any post-editing undertaken to correct hiss. I note that Philip Bloom also used this mic and didn't report the problem...ah well, will just need to make do

In the right conditions it is possible to not have the AGC too noticable, but your experience was the same as mine prior to the DXA-5D

For the 7D, you need two things: a hot signal, and a way to defeat the automatic level control (ALC).

The DXA-5D defeats auto-gain, but doesn't include an amplifier. It uses a high frequency signal, so you can record two channels of sound.

juicedLink has the CX211 and CX231 preamps that offer gain. You can add on the DN101 to defeat the ALC. It uses white noise into one channel. The advantage is that there is no tone to remove in post. The disadvantage is that you will only record one channel.

You can also use an active preamp to add gain and hook up an MP3 player that blasts white noise into one channel of the 7D. That will give you gain and kill the ALC, but it won't give you headphones or meters.

The best sound will come when we can get Magic Lantern on the 7D.

You can check out my six part series on 5D2 audio here:

vimeo.com/5370880