Having an interesting LCR (3.0) playback issue

Question

I am teaching my students how to do LCR (3.0) through quicktime mov and when I ran a test in a teaching venue, we got all our discrete channels correct but when we disabled our centre channel which has dialogue, sound effects and foley on it, you can hear that all of these sounds coming through the left and right which has the ambiance and music. The sounds are a lot lower than when they come through the centre but it is still a problem.

When the LCR was delivered to the editor, they assigned all the channels to their correct discrete channels and the left and right was panned off and the centre channel pan was in the centre. We ran the test a few times changed the distribution of the tracks from LCR to LRC etc but we still had centre channel bleed into left and right.

It could be our system but before I start to take apart our system I just want to know if anyone has had this problem before?

Thank you

Answer 1

It sounds like it could be one of several possible causes:

• An effect used in the signal processing during playback. Without knowing what your playback system is, this is just sheer guesswork.
• Bleed that was imprinted at mixdown time due to simple channel bleed or due to signal processing

Questions:

Are you using active monitors with dedicated signal processing or passive monitoring with separate amplifiers?

If active, what is the brand and model and are there different modes for playback?

You mentioned that the ambience is assigned to left and right. Is it possible that what you're hearing is the imprinted ambience, which happened to include the "ambience" of the center channel?

Can you verify at the editing suite (or wherever the mix was delivered for final output) that there IS or IS NOT bleed of the center mix to the left and right? Personally, I would start there at the editing suite and verify that your assumptions are correct before dismantling your playback system.

I hope that helps, but answers to my questions would be helpful in narrowing down a long list of possible causes. Regardless, I wish you good luck in determining what's responsible and I request that you come back and tell us what was the cause, if you find it.

Answer 2

If your laying back the tracks in Quicktime you want them to be assigned to "Lfet" "Center" and "Right" no panning involved. Otherwise maybe you have some divergence or bleed on your center channel feed.