Part 2 where I show how to create a cable that will disable the AGC (with the addition of a noise source).
Note: I tried a new render encoder on this video and it appears that the audio is a little out of sync. (I used the Sony AVC *.mp4 codec – this also creates a file 3 times larger than the MainConcept encoder) – yes, I am always testing. 
Sorry it has taken me a bit longer to publish part two of this hack to disable your AGC on your Canon DSLR (7D, T2i 550D).
Our family took a trip to Ouray Colorado to visit some friends over the 4th of July weekend where I took hundreds of photos and tons of video clips.
I am getting more and more comfortable taking pictures and video with just one camera now.
Anyway back to the hack to disable the AGC.
If you haven’t yet, go back and watch part one of this hack where I demonstrate the differences between the AGC enabled and disabled.
Part 2
From Tarvi Roos For the Mac Final Cut Pro Users
To create this adapter you will need two stereo 1/8″ jack connectors and one 1/8″ stereo plug. That is about $8 in connectors.
I had some old West Penn 2 conductor #22 gauge stranded shield cable lying around that I used for the audio cable.
You don’t need something as professional as West Penn wire but you should buy the best cable you can find because we are unbalancing the Rode Videomic which means you will not want to remote this microphone more than 20′ away because it will probably pick up a lot of electromagnetic noise around other electrical devices. I have remoted this cable over 10 feet without any noise or frequency response issues.
Strip back the wire and solder the red wire to the tip, black wire to the ring and the shield to the sleeve.
On the connector that will plug into your Canon camera, connect the red wire from the mic connector to the tip of the 1/8″ plug and the red wire of the mp3 player to the ring of the 1/8″ plug. Clip off off the black wire for each. Then solder both shields to the sleeve to the 1/8″ plug.
You might think you can just buy one of these y-adapters from radio shack like I did but you can see that the shield is missing from the connector which is required for this to work so don’t waste your money on this connector.
Then connect your Videomic and your mp3 player and then connect to your T2i 550d or 7d.
What I liked about having an mp3 player is I can accurately reset my level adjustment on my mp3 player each time. You can use many other things for this like a metronome tone or even a pick noise generator.
You need to accurately set the level each time you record. If the level is to low it won’t squash the AGC all the way but too much and you can get cross talk in to the mic channel. Even though I can’t hear anything above 16k since I was a teenager you can still hear some of the sub harmonics of the tone but it is not too annoying on playback on the small t2i speaker.
Download the 19kHz tone (one hour long). Right click and “save target as” (unless you are really young you will not be able to hear this).
That is pretty much it, watch part I on how to processes the audio tracks.
Some Picture from the July 4th Weekend
I dont have a Rode microphone but i do have an external mic, but will this hack work with other external mics? I have a Audio Technica ATR-6250
Thanks
Hi there
What if you use the analog video output of the camera and inject it into one of the channels
It might be too loud and we’ll get some crosstalk. Give it a try and show the results!!!
If the video sync signal is too loud, just add a resistor and a ceramic condenser (as a lowpass filter) until you get the right amount of “signal” into one channel!!!
The video mic pro has built in 20 db gain. Will that solve the abc problem without the hack?
Agc
Hello,
I´ve tried the same procedure like you explained in your site, but with another microphone -Zoom H2- it doesn´t worked. By wathing the the recorded videos you can hear the 19khz noises. Can you help me please to solve this problem.
Best greetings from Germany
ozo
@ozo sorry I only know it works for the Rode Videomic
Hello sir, How do I sync the audible noise you have on your site to the mp3 player?
Thanks for the post. I will be visiting your blog soon! Cheers!
Hey Dave,
Your videos really helped me with learning DSLR for videos and also buying my gear.
I was surprised that my T3i had some constant loud hiss and noise with a Rode Videomic.
The problem wasn’t AGC because of the manual audio control, but still i follow the steps and built the AGC hack setup thinking it would stop the hiss. First I did a test with manual control and turning on and off the mp3 player didn’t change nothing to the audio (and the hiss just kept loud). Then I tried with automatic audio, just like your setting and it really worked! The AGC hack with auto audio was better than just the manual settings (with or without the hack).
I searched on the internet about the T3i’s audio problems and found almost nothing.
(I’ve use another solution that is recording the audio externally with a cheap camcorder and the rode mic and it is was great also.)
Maybe if owners of the T3i (and even 60d’s) knew about this they would be pleased of the solution.
For me, I’m sticking with the simple AGC hack with T3i’s automatic audio control.
I just don’t know why the heck is there a problem with the manual audio control of the T3i
Thanks a lot, man
If you want, I can give you more details!
Does anyone know if this will work with the Rode Videomic PRO? I have a similar cable but all I got was a quieter hiss yet no voice with my video.