Canon 7D/T2i AGC Bypass Trick

Like my "Red Pad Rockband Fix" video, I enjoy finding these cheap workarounds to expensive problems and logging it somewhere for the benefit of the community.

In this case, I am tackling the dreaded AGC 'feature' on the Canon 7D and T2i.

Here's a copy of the tone in a 30 minute mp3:
http://bit.ly/9C0hSR

Category:

Howto & Style

Tags:

• canon
• EOS
• dslr
• video
• hack
• bypass
• gdc
• magic
• lantern
• 5dfilmschool
• adapter
• rig
• hellaghetto
• cheap
• diy
• do
• it
• yourself
• biymcanonLOL
• firmware
• lenses
• camera
• camcorder
• mic
• amp
• preamp
• spoof

[ReberthFilms]

This trick lowers the gain, but it DOES NOT disable it or give you a constant level. After following the instructions exactly I can report:

(1) Much improved agc / audible hiss

(2) Gain still increases very slightly during silence on the mic channel

(3) The auto levels still clamp down harshly when someone starts talking

So you get much much more usable audio then without this trick, but you don't get a constant level and you're much more prone to clipping then with an external recorder.

[wowfony]

@ReberthFilms You have to crank the MP3 player, and make sure the generated tone is normalized to 0db for it to push it down to the point of zero auto-gain.

[papikache]

WowFony i am about to go buy the adapter it sounds great. question. besides playing the 20 min clip while recording do i need to set any aoudio settings on my 7d? or is just plug and play?

[wowfony]

@papikache plug and play.. if you are using a rode videomic, you'll need another adapter. It's a 1/8 stereo to 1/8 mono (I think)

[KowalFilms]

If anyone really wants Canon to update the firmware to the 7d, please write them a letter. Here is the link to their site. Click on the Professional Services tab and leave a comment.

usa.canon. com/cusa/professional?pageKeyC­ode=contactUsLanding

[KeroroGunsouTX]

I am really disappointed with Canon. I wish I had known about this problem beforehand I would have never bought one of their cameras.

[shadeogray1]

Well I inquired several times about the AGC issue and I actualy got a rely this time. Unfortunately, the response pretty much told all 7D owners to go F them selves:

Thank you for your inquiry about adding Audio Gain Control to the EOS 7D. We value you as a Canon customer and appreciate the opportunity to assist you.

[paul1010hotmailcom]

An old trick to extend the dynamic range is to record the signal into both channels of a stereo recorder, but you attenuate ONE channel by say 20dB. Then on playback, choose the attenuated version for loud sounds (so it won't clip), and the the non-attenuated version for quiet sounds (to minimise hiss). Any tried this on the T2 or 7D?

[strewnshank]

That's a great trick.... Side chain, basically. Smart

[AandDProductions1000]

smart ! thanks

[DirectorJesseHicks]

IPOD!!! that's amazing. I was aware of this problem with the 7d. but never thought of the ipod. awesome idea. thank you

[JonandSamTV]

@wowfony I got the 1/8 stereo to 1/8 mono, and the Y adapter, with an iPod, playing the tone, and it didn't fix the problem for the rode video mic. :( Any suggestions? Or has this already been proven fact, that you can't use this technique for the rode videomic?

[21jake21]

@cannedgravy rub it in..

[rafaelunplugged]

how do you reduce it when the sound from the tone mixes into the sound of the microphone line? its very noticeable.