External mic to Zoom H4N to 5D2

[eco_bach1]

Hi
Thinking of getting this cable
http://www.sescom.com/product.asp?item=LN2MIC-ZOOMH4N
to patch the audio out from my H4N to my ML hacked 5D2.

From what I've read elsewhere, even if you do this, the audio recorded by the Zoom is still going to be far superior than that in the 5D2.

Can anyone confirm this and explain why?

[ZeroUnityGain]

Hi Mate,
I've used the H4N, but I'm not too familiar with the 5D2--I've got the 550D.  I suppose what you're trying to do is utilize the H4N's XLRs and mic-pres to get a good recording and then send that to the 5D2 to  use as your audio track -- rather than line up the H4N's audio.  I suppose you have to look at the rationale behind doing that.
You would be bringing a mic signal into the H4N and using its mic pres to boost the mic signal up to line level.
As you know what good mic pres do is make a nice clean boost to line level from a signal that is sometimes as much as -60db -- that's 60db below line level.  So if the mic pres aren't nice, noise-free amps they just boost any inherent noise as well.  That's the theory.   But look at what you are proposing: To boost that low level mic signal in the Zoom and then pad it back down to mic level and then boost it again in the Canon using its mic pres.
Well that's the theory but my tests have shown that it doesn't even work that way. Damn! 
In the 550D there's that troublesome AGC, which ML can disable.  I think you can manually disable this in the 5D2, but I'm not sure. 
But once you disable the AGC (Automatic gain control, which raises and lowers gain automatically) my tests have shown that the camera's input is back to line level.  So buying a cable that is padding your signal to mic level would be pretty useless.
Since you have the Zoom and the camera a simple experiment would be to disable the AGC in the camera and simply run line level into the camera (not sure if you can attenuate this from the Zoom, but that would help).

In summary, I don't have a problem with the 550D's audio recording quality, in fact, I've found it's quite good. But once you disable the AGC--because it's noisy--you need to pre-amp any microphones before going into the camera--like with a mixer or a mic pre amp.

And just a word on XRLs.  The only advantage of an XLR is that it is balanced.  Balancing simply means that the same audio is run in-phase on pin 2 and out-of-phase on pin 3, and pin one is earth.  What happens is that any noise picked up by the cable cannot be exactly the same  on both pins 2 and 3 -- because it's intermittent noise.
But any audio originating from the source (like the microphone) is, of course the same on both bins.  So a summing amp at the input stage of a balanced XLR input simply discards anything that is not exactly the same on both pins--like noise.  This is useful on long runs where cable become susceptible to noise--but generally on short runs this is not a problem. 

[Malcolm Debono]

From what I've read elsewhere, even if you do this, the audio recorded by the Zoom is still going to be far superior than that in the 5D2.
Can anyone confirm this and explain why?

2 reasons:

• You are using the H4N's preamps instead of the camera's preamps (which should result in cleaner audio)
• Recording on the H4N is a WAV file (uncompressed) (as opposed to the compressed audio track in the video)

Just make sure to get a decent mic that's suitable for your purposes.