Exact Input Impedance of 5D2?

D

David Yoyo

New member
In my quest to make a custom attenuator/pad cable to hook a mixpre up to my 5D2, I would love to know what the input impendance of the camera is?
I have made a few cables so far, but even though I am getting very close, I am not sure the resistors actually have the right values to match the cam and mixer.
Is the input impedance a hardwired value or has it changed with firmware upgrades? Is it the same with or without Magic Lantern. Does it change with amount of gain in camera, no right?
I have searched all over and found quite fluctuating figures like 600ohm, 4 K and 10 K.
Can I measure this directly with a multimeter? I don't think so, right?

All best,
David
 
I think there are 2 issues to be taking into consideration. First is the input impedance of the mic input. Second is the gain of the 5D2 mic-preamp. The latter is more important in your case since you have to adjust(drop) the output signal from you mixer before feeding into the 5D2.

If I were you I will experiment by dropping the mixer output signal with a resistor network, say, grouding the signal with a 5K resistor and feeding the divided signal through a 100K resistor to the 5D2.
 
OK, thanks for the input. I am trying to make the perfect pad - not only in terms of value of dB, but exact values of resistors. I have a pad that has the right dB. But I am not sure whether the resistor values are correct to match impedances of MixPre and cam. The gain, I don't think has anything to do with it. From my research on getting the right values for the resistors, I have found that one needs the impedances at both ends. I know the impedance of the mixer, but not the cam.

Best,
D.
 
Hi Derek,
thanks for the link. Good, but not exactly what I was looking for as she does not come up with any specific values. Perhaps, I should just end my quest. I have a pad that works and it may not be theoretically perfect but since I am not sure how much that means - if it can land me in trouble, I may just have to get on with life.
Anyways, for others making pads - here are a few succesful attempts, though not varible like the one in the above link.

http://www.cinema5d.com/viewtopic.php?f=75&t=12985

D.
 
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