Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Robert Lunceford]

I worked at a documentary film festival yesterday where there was a live band playing to a film.
The first section was a film that included an audio track along with a live voice over. After the first section I was to mute the audio track of the film at my board, which I did, as the band played music for the rest of the film.
After the first musical piece by the band, I could faintly hear the film's audio track coming through the sound system even though the channel was muted. I unplugged the feed from the film at my board to get rid of the audio leaking through.
I believe the film was being played from either a laptop or from the theater's server. I was given a single channel XLR feed from their projection room. This feed was plugged into channel 24 on the QU mixer. Gain adjustment was at minimum as the signal they gave me was pretty hot.
Any ideas of how audio could have been passing through the mixer with the channel muted?

[Mark Amber]

This is not un heard of on the mixers like a mackie VLZ but certainly surprised on a QU. Let us know how it goes. Maybe A@H can help out.

Sent from my Pixel using Tapatalk

[Robert Lunceford]

One thing to add. There was a wireless mic in channel 23.
Wireless was operating in the upper 600 region.

[Magnus Högkvist]

Any ideas of how audio could have been passing through the mixer with the channel muted?

Pre mute send to a monitor mix? So what You actually was hearing was a monitor and not the PA.

[Roland Clarke]

Pre mute send to a monitor mix? So what You actually was hearing was a monitor and not the PA.

This was my initial though.  I don't like the QU as a mixer.

[Gordon Brinton]

I worked at a documentary film festival yesterday where there was a live band playing to a film.
The first section was a film that included an audio track along with a live voice over. After the first section I was to mute the audio track of the film at my board, which I did, as the band played music for the rest of the film.
After the first musical piece by the band, I could faintly hear the film's audio track coming through the sound system even though the channel was muted. I unplugged the feed from the film at my board to get rid of the audio leaking through.
I believe the film was being played from either a laptop or from the theater's server. I was given a single channel XLR feed from their projection room. This feed was plugged into channel 24 on the QU mixer. Gain adjustment was at minimum as the signal they gave me was pretty hot.
Any ideas of how audio could have been passing through the mixer with the channel muted?

The manual says that the mute button affects all sends, including groups, FX, and mixes. The only way I can see how a leak might occur is if an Effect or Ducker is inserted directly into the channel. The insert point comes before the mute. See the attached diagram.

To check it...
Touch the fader strip SELECT key, (for channel 24).
Press the PROCESSING Key.
Touch the upper-left part of the screen to see the Input Parameters.
Notice if the INSERT button is lit up.


...Or simply mute the FX channels to see if the leak goes away.

[Robert Lunceford]

I set up the mixer (still in same configuration from the film fest) and hooked up mains, monitors, audio source into CH24, and wireless in CH23. I could not duplicate the problem. When I engaged the CH24 mute it muted signal to both mains and monitors. No inserts in any channel. I'm baffled.
It is an educated guess that the music coming through the system was the audio track from the video but I do not know for sure. Once I unplugged the send from the projection room to my mixer I never had the problem again.

[Stephen Swaffer]

Silly thought, but is it possible it PFL selected coming through headphones?  Sometimes it can be hard to localize a low level sound.

[Geoff Doane]

If the signal coming from the projector is somehow driving the shield of the cable (as well as pins 2 and 3) I can see that it might be modulating the ground of the console and that sound is then leaking out.  I've seen that kind of problem with SMPTE feeds into cameras (Sony likes to use unbalanced BNCs for time code) from balanced sources, and it creates nasty crosstalk, even with a moderate time code level.

This is essentially a "pin 1 problem" (if that is actually what is happening), and so far my experience with the QU-16 has been very good in that regard.  I have one set up right now with simple hard wired splits on 12 inputs between it and another console in another room, and there isn't even a hint of a ground loop.  I do have at least one very hot line level signal (coming back from the other console), so I should probably see if it is being muted completely.

GTD

[Rob Bernstein]

I worked at a documentary film festival yesterday where there was a live band playing to a film.
The first section was a film that included an audio track along with a live voice over. After the first section I was to mute the audio track of the film at my board, which I did, as the band played music for the rest of the film.
After the first musical piece by the band, I could faintly hear the film's audio track coming through the sound system even though the channel was muted. I unplugged the feed from the film at my board to get rid of the audio leaking through.
I believe the film was being played from either a laptop or from the theater's server. I was given a single channel XLR feed from their projection room. This feed was plugged into channel 24 on the QU mixer. Gain adjustment was at minimum as the signal they gave me was pretty hot.
Any ideas of how audio could have been passing through the mixer with the channel muted?

I have done over 100 shows with my Qu-16, have never had an issue like this. I mostly use the Qu-SB now but these are essentially the same engine. Have been reliable night after night. Not sure what was going on with yours.

[Robert Lunceford]

If the signal coming from the projector is somehow driving the shield of the cable (as well as pins 2 and 3) I can see that it might be modulating the ground of the console and that sound is then leaking out.  I've seen that kind of problem with SMPTE feeds into cameras (Sony likes to use unbalanced BNCs for time code) from balanced sources, and it creates nasty crosstalk, even with a moderate time code level.

This is essentially a "pin 1 problem" (if that is actually what is happening), and so far my experience with the QU-16 has been very good in that regard.  I have one set up right now with simple hard wired splits on 12 inputs between it and another console in another room, and there isn't even a hint of a ground loop.  I do have at least one very hot line level signal (coming back from the other console), so I should probably see if it is being muted completely.

GTD

You may be on the right track. I believe the feed I was getting was taken from the laptop's stereo minijack, then into a stereo miniplug to mono RCA adapter, then to a RCA to XLR adapter.

[ProSoundWeb Community]