Field mixer for gain control on DSLR?

O

Oaken

Active member
Anyone know or have tried to use a field mixer as a go between to DSLR? I have a nice mixer I use with a boom with 1/8inch output. I was thinking of using that instead of a H4N and record directly to say a T2I or something. Would that help with the auto gain or would it matter as the camera senses levels anyway. The bonus would be I can use headphones through the mixer at least.
 
Not the best idea. Think about the sound quality in the camera, much better quality off the H4N. Just use the DSLR for scratch.
 
First problem: The T2i has absolutely no manual control over audio, and the AGC (Automatic Gain Control) must be deactivated in order to record anything resembling usable audio. This can only be done by using a firmware hack such as Magic Lantern.

Second problem: The 1/8" output of your mixer is most likely line-level. The 1/8" input on the T2i is mic-level. Pumping a line-level signal into a mic-level input can damage audio circuits, and turning the input gain almost all the way down to compensate leaves you little wiggle room for proper gain staging. You'll need to get a padded line-to-mic 1/8" cable.

Third problem: If you are at all concerned about high-end sound quality (in other words, if you are doing anything that isn't Internet-only distribution) then internal audio on a T2i still isn't the best solution.
 
C2V said:
First problem: The T2i has absolutely no manual control over audio, and the AGC (Automatic Gain Control) must be deactivated in order to record anything resembling usable audio. This can only be done by using a firmware hack such as Magic Lantern.
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Or a Juicedlink device I'd imagine.


C2V said:
Second problem: The 1/8" output of your mixer is most likely line-level. The 1/8" input on the T2i is mic-level. Pumping a line-level signal into a mic-level input can damage audio circuits, and turning the input gain almost all the way down to compensate leaves you little wiggle room for proper gain staging. You'll need to get a padded line-to-mic 1/8" cable.
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That's exactly what I do and this is what it sounds like with a 5DMKII:

http://www.santucci-cinematographer.com/MISC/MVI_3253.aiff
 
Chris Santucci said:
Or a Juicedlink device I'd imagine.
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Yes, there are boxes from JuicedLink that use one of the two channels to send a tone that (sort of) defeats AGC without a firmware hack. This doesn't improve the quality, and you sacrifice 2-channel recording.

Chris Santucci said:
That's exactly what I do and this is what it sounds like with a 5DMKII:

http://www.santucci-cinematographer.com/MISC/MVI_3253.aiff
Click to expand...

To be honest, that sounds bad to me. It's very thin, and is plagued with distortion on the peaks... analog distortion, which is probably happening in the camera's pre-amp. Though, not knowing your full signal flow, it could be happening somewhere upstream... but knowing that you're pumping a line-level signal in and just turning the camera's gain all the way down tells me this is the likely culprit.
 
I really wouldn't bother. I record on a 7d with a small mic, but it's purely gun &run.quality audio needs end to end quality, IMHO.
 
I spent 10 minutes tweaking the gain settings and have achieved a much better balance. It's super-clean. Thanks for the feedback.
 
Thanks everyone I think I'll get an H4N just to be safe. But being able to record to the camera in a pinch would be great. Also the Beachtech series looks like a good way to go.
 
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