Disabling the Canon AGC

[ZeroUnityGain]

Hi Guys,

Saw the video about disabling the AGC and using a mic pre.  Does this mean that the AGC in the Canon (I've got the 550D) is incorporated in the microphone preamp.  Because I really didn't want to use an external mic pre.
I'm using a nice pro Sony electret condenser mic (battery operated) and I just want to disable the AGC and take advantage of ML's input sensitivity controls.  I suppose I could try it, but can you not use the ML -- or disable ML if it doesn't work this way?

Thanks

ZUG

[ZeroUnityGain]

I'll try another approach:  Has anyone used the ML audio feature of disabling the AGC and then plugged a mic straight into the camera -- and what was the signal like?

[nanomad]

AGC should have nothing to do with the amplifier. An amplifier simply "boosts" or "pulls up" the signal level of a fixed amount (i.e. +5db). AGC acts like a variable amplifier, aiming for an average "audible" signal level throughout the whole recording thus boosting silences and producing horrible hisses. So, unless the engineer was dumb, AGC off should simply disable AGC while leaving mic boost untouched. You may need a higher boost though (due to AGC being off and not trying to pull up the signal by itself)

[ZeroUnityGain]

AGC should have nothing to do with the amplifier. An amplifier simply "boosts" or "pulls up" the signal level of a fixed amount (i.e. +5db). AGC acts like a variable amplifier, aiming for an average "audible" signal level throughout the whole recording thus boosting silences and producing horrible hisses. So, unless the engineer was dumb, AGC off should simply disable AGC while leaving mic boost untouched. You may need a higher boost though (due to AGC being off and not trying to pull up the signal by itself)

Yep, understand all that.  Used to use AGCs or Levellers + mic pres in the analogue world.  Actually mics can be down around -60db and the mic pre usually pulls that up to around +4 or 0db line level. 
I'm quite happy with the Canon mic pre but the AGC is giving me a prob.
But thanks very much for your response, as I'm getting more confident that what you are saying is correct of the Canon.  What threw me off is the actual ML video, which wants you to use a JuicedLink pre-amp -- but when I listened to the JuicedLink video instructions, although they keep singing the praises of their mic preamps, you ultimately have to connect the unit's microphone output to the camera's mic input.  Of course this runs against everything I've ever done in my life: Like why use mic preamps -- which were always designed to boost to line lever -- and then pad the signal back down to mic level for the camera's mic preamp to re-boost.  Doesn't make any sense at all to me. 
So I think you have answered the question.  Thanks.