I could really use a continous running (automated) test that gives me a green positive or red negative, depending on the polarity relation of input to output. Is this on the to-do list?
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This is an excellent idea!
Hi @philipppaulklose, the QA401 had a measurement tile that indicated degrees (at the current frequency), and also a mic-test plug-in that would give a go/nogo test on polarity. I will look at getting something resurrected. The measurement tile would look at phase difference between output and input.
For an automated test, you can use the AMP frequency Response Chirp and take a look at the plotted phase.
Do you think a measurement tile that works in single-tone mode that displays phase degrees (output versus input) at the current frequency would be helpful? This will get confused if the amp has any DSP. In those cases, the AMP Frequency Response Chirp with right channel as reference will be needed.
Thanks so much for considering this! QA401 is before my time 
Polarity testing is always to be taken with a grain of salt especially when DSP is involved and in small acoustic environments. A measurement is always an accompanying thing to do.
I like NTI‘s approach on polarity testing. They use a looped impulse and split the received signal into several bands (I think it is five or seven bands) and then show the results (pos, neg) per each band.
I made a phase test for Tractor a few months ago if you want to check it out. There’s one for the QA401 and one for the QA403. I think I made one that just does 180 polarity checks against a reference before and after you manually flip the polarity. I’ll have to dig it up if you’re interested in that one as well.
Cheers.
Tom
The easiest way IMO is an asymmetrically clipped sine, viewed in the time domain. (scope). Or run a series of impulses (one polarity) and view. Doesn’t matter if there’s delays or DSP then.