There are no standards to preserve absolute phase in any items of audio equipment - and I would only worry if the main L+R outputs were out of phase with each other!
Occasionally with microphones you might see it specified that a positive going increase in air pressure on the diaphragm with result in a positive going output on XLR pin 2, but this is not generally done for power amplifiers, mixing desks or other parts of the audio chain.
It is easy to make up a useful device with just a resistor (almost any value from 1 - 10K ohms for example) and a small signal diode, such as a silicon signal diode 1N4148.
Connect the resistor in series with the sine wave generator and the diode from the output side of this resistor to earth.
I have made one in a very small die cast aluminium box fitted with jack sockets for input and output - making this sort of test very quick to carry out.
If you apply a 1 volt sine wave to this network - the output waveform will have the top (or bottom, depending on which way around you connect the diode) of the waveform clipped, or squared off.
You now apply this asymmetrical waveform to the amplifier or mixer under test and observe the output on a scope - it is easy to see if any inversion has occurred.
Occasionally with microphones you might see it specified that a positive going increase in air pressure on the diaphragm with result in a positive going output on XLR pin 2, but this is not generally done for power amplifiers, mixing desks or other parts of the audio chain.
It is easy to make up a useful device with just a resistor (almost any value from 1 - 10K ohms for example) and a small signal diode, such as a silicon signal diode 1N4148.
Connect the resistor in series with the sine wave generator and the diode from the output side of this resistor to earth.
I have made one in a very small die cast aluminium box fitted with jack sockets for input and output - making this sort of test very quick to carry out.
If you apply a 1 volt sine wave to this network - the output waveform will have the top (or bottom, depending on which way around you connect the diode) of the waveform clipped, or squared off.
You now apply this asymmetrical waveform to the amplifier or mixer under test and observe the output on a scope - it is easy to see if any inversion has occurred.
Otherwise take a messurement software like ARTA (free to download)
Then you can make line messurements up your line and observe the impuls answer. This is going to show you if your output is the same polarity like the innicial signal. Polarity is what you are looking for, not phase. Phase will shift occasionally by filters used.
Arta gives you a signal which can be fed to any input at the desk.
Just make shure that the cables you use for hoocking up the mixer to your soundcard are correct.
Then you can make line messurements up your line and observe the impuls answer. This is going to show you if your output is the same polarity like the innicial signal. Polarity is what you are looking for, not phase. Phase will shift occasionally by filters used.
Arta gives you a signal which can be fed to any input at the desk.
Just make shure that the cables you use for hoocking up the mixer to your soundcard are correct.
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