C300: C300 MK3 MIC terminal audio question

M

MartinF

Active member
Hi all, I need your help.
I want to connect two sources to the MIC terminal of my C300-3 and record them to channels 3 and 4, in my case two Sennheiser AVX receivers. I tried to do it using a WoodenCamera A-Box DSLR as well using a simple splitter Cable.
And while it works how I was expecting it to (one receiver goes to CH3 and the other to CH4) the signal is bleeding quietly into the other channel, meaning you always record the signal from MIC R/CH3 also to MIC L/CH4, although very quiet. This renders the whole setup useless, as you never get a clean recording of the different channels on the MIC input.
Anybody else had that problem? Is my camera broken or is this normal behaviour of the MIC terminal?
Which also leads to the question if it is a good idea to record a stereo mic via the MIC terminal or if a dual channel receiver like the Sony URX-P03D even makes sense if you connect it to the MIC terminal to get two wireless signals into the camera...
Thanks for any clues!

PS: please don't tell me to hire a sound guy, I enjoy working alone, this is a purely technical question :)
 
Thanks Rob, oddly enough that is exactly the same cable I tried (next to the Wooden Camera A-Box). And you don't get the bleeding of one channel into the other?
 
MartinF said:
Thanks Rob, oddly enough that is exactly the same cable I tried (next to the Wooden Camera A-Box). And you don't get the bleeding of one channel into the other?
Click to expand...

I don’t think so but will test and report back. Are you using the a-box at the same time as the hosa cable/have you tried the cable only?
 
It's either or, as the A-Box has a 3.5 stereo plug as well. But both give the same bleeding effect. I just ordered another splitter cable to try, dual xlr female to 3.5 stereo plug, but I don;t have high hopes...
Thank you for taking the time to test!
 
How did you discover this issue? Meaning...can you hear it in your headphones when monitoring? Or only on the computer?

If the latter, is it possible it's a post/post-production handling problem?
 
You can hear it in the headphones and see it on the meters. I discovered it setting up my rig for a shoot where I needed to lav two people. Wanted to keep my shotgun on Ch1 with CH2 as a safety track and record the lavs to 3 and 4. I am using the Sennheiser AVX system, which works great when you are working alone as it has an insane dynamic range and you hardly ever have to change the levels once you set it. I did that a lot back in the days when I was still an FS7 owner, always worked perfectly with that little XLR accessorie for the MI shoe.
I also checked it with the splitter cable and two cheap rode videomics, problem is still there, so it got nothing to do with the AVXs or their supplied XLR to mini jack cables.
 
If you haven't already, try the most common troubleshooting like resetting the camera, switching inputs, turning phantom power and and off (if applicable), and trying another wireless system, if possible.

However, I just said the same thing last week to someone else who was having an issue with their audio on a Canon camera and that didn't help.
 
Are you sure the cross talk is a camera audio issue, or could you just be getting pickup of both people on both lav mics acoustically? If the lavs are omni-directional this is likely unavoidable in a typical two-shot scenario.
I use a Sennheiser AVX system too. The omni heads on those lavs are sensitive enough that I often use mine as a boundary mic on a table top between two talkers.
There is a trick you can try in post. Switch one of the lav audio tracks 180 out of phase. It might cancel some of the cross talk. Or set up gates on the lav tracks in a DAW and set threshold above the cross talk level.
 
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It is not that the lavs pick up both sources, I tried it with the lavs in two different rooms: one was like 10 meters away behind a wall and under a blanket together with my phone playing some music, the other channel still recorded that lav. So, no, it must be either the splitter cable/A-Box, the 3.5 stereo plug on both of those or the camera itself responsible for the bleeding of the signal into the other channel. And as I mentioned before, it also happens with other mics than lavs...

Did anyone here ever try a Sony URX-P03D dual channel receiver on the MIC port of the C300-3? Would love to know if that one gives a clean signal to both channels or if it also suffers from that bleeding effect...
 
To finish this up:
I talked to CPS about the issue and they basically told me that it is not possible to get two clean channels from the MIC terminal and that there always is cross talk between the the left and right signal. The only way to get another two channels is to use the extension unit.
 
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