Is it possible for audio on one track to "bleed" into another?

nedcam

nedcam

Well-known member
I know it was possible in the analog days, we'd sometimes have time code bleed into an audio track.

I had a loud fan noise (camera mic) on channel 4. I don't believe that can affect audio on the other channels, correct? I don't think digital can "bleed". Anyone know a lot about this?

The camera in question had it's audio controls up max because the sound from the board (live event) were low.

Thanks,

Ned
 
There is always crosstalk when the analog stages are in the same device and there is a rating for that in dB. An analog to digital converter does not remove the existing crosstalk, it just adds a little more. There is no crosstalk created by the fact that the digital files are in the same media, that's the only difference from a fully analog device.
 
I got an answer from Trew Audio: no bleed in digital audio tracks. They probably had not muted Channel 4 so we're listening to all tracks at once, thinking the fan noise was on the good tracks. Pheeew!!
 
nedcam said:
I got an answer from Trew Audio: no bleed in digital audio tracks. They probably had not muted Channel 4 so we're listening to all tracks at once, thinking the fan noise was on the good tracks. Pheeew!!
Click to expand...

Glad it was something so obvious. "No bleed is digital audio tracks" is certainly BS. Only the storage is digital, everything from the mic to the mic preamp and down to (and including) the AD converter is analog and has crosstalk. The only digital recorder that is free from crosstalk is a recorder with digital audio inputs.
 
Otis Grapsas said:
Glad it was something so obvious. "No bleed is digital audio tracks" is certainly BS. Only the storage is digital, everything from the mic to the mic preamp and down to (and including) the AD converter is analog and has crosstalk. The only digital recorder that is free from crosstalk is a recorder with digital audio inputs.
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This is true. But if the circuitry was designed well, the crosstalk should be
at a decibel level (-70 or more) that would be imperceptible in the track.

If the crosstalk is perceptible, then you should debug your analog chain to
figure out where it's coming from. From the HPX300 audio inputs in, you
should hear zero crosstalk.

jeff
 
jmarkham said:
This is true. But if the circuitry was designed well, the crosstalk should be
at a decibel level (-70 or more) that would be imperceptible in the track.

If the crosstalk is perceptible, then you should debug your analog chain to
figure out where it's coming from. From the HPX300 audio inputs in, you
should hear zero crosstalk.

jeff
Click to expand...

Better than 70 probably. John Beale tested a DVX at some point and it was -70dB at the worst point.
 
if you have noise one channel and it bleeds into the other, you can usually remove it by putting into Protools and summing the two tracks and then putting the noisy track out of phase.
 
A lot lot editors inc me are not used to four audio tracks from a camera, crosstalk is possible in the analogue stage of the matrix but i have generally found the 301 to be very good for audio and it is very flexible to the extent that I mostly don't use a mixer and use those four tracks to the max!
 
ksteiger said:
if you have noise one channel and it bleeds into the other, you can usually remove it by putting into Protools and summing the two tracks and then putting the noisy track out of phase.
Click to expand...

It's the same signal and it's in sync, but the frequency response is unknown and not always flat. Changing just the level of the new (phase inverted) copy of CH2 that is added to the CH1 can fix 80% or even 90% of it. A little extra EQ on the CH2 copy can almost fix 100%.
 
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