Hello all,

I use a Chromatec AM-2 as a PPM when mixing for TV (I also run an RTW Portamonitor too), along the bottom of my TV is a bar which checks for phase.

My question is this, when I pan something in ProTools all the way to the right/left (100) I get a phase error? What actually causes this error, physically?

I know why a stereo sound will cause a phase error, but this is a mono sound panned.

I always set my FX and Music buses to 75 pan either side as this corrects the vast majority of errors caused by either panning or stereo files.

  • What is a "phase error"? It shows a warning when the right and left channels have opposite polarity?
    – endolith
    Aug 12, 2010 at 14:21
  • Correct! It's a sliding bar that goes purple if an error occurs. It's mainly caused by stereo audio when you mono it. This mono thing is just strange.
    – ianjpalmer
    Aug 12, 2010 at 19:06
  • It doesn't make any sense. There is no way a mono file can be "out of phase". If it happens on all mono files no matter what, I'd disregard it because all you're doing is assigning it out to one channel and not the other - there can not be a phase problem with it.
    – Utopia
    Aug 13, 2010 at 0:55
  • Well bringing in the FX bus to 75 on each side cures the problem and I've certainly never failed QC, been like this since I started working here and no one here can explain either. Gremlins methinks as you're right it makes no sense what so ever.
    – ianjpalmer
    Aug 13, 2010 at 9:30

1 Answer 1


No offend but when you say you get an phase error does the correlator go to the center or full to the red zone?

If the latter occurs it may be because of the sound path between DACs and correlation meter. Do you have Phasescope plug-in? That would help to find oud what is going on.

Small amounts of delay between channels can cause phase inverted metering at the correlator for certain freqs, too. When I use delay to spread some mono sounds it´s usual to see the correlator at the center, buncing to the red zone. I use to insert a Phasescope instance at the main outputs in ProTools and I use an external computer with Pinguin Meter for spectrum an XY fast metering. Most of time I use XY metering since it gives more information about these signals.

  • No offence taken. The meter goes all the way to the left (forget which colour it is off the top of my head). My RTW is a different beast and reacts in a totally different manner. However I've not tried a plugin. I'll have a play this week and see if I can narrow down what's happening with all the meters and report back.
    – ianjpalmer
    Sep 10, 2010 at 20:25

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