How To Diagnose Phase
Did I ever mention I nearly wanted to pull my hair out. Is there a solution? Thanks to the Don, yes there is an easy way to determine your system’s phase (i.e. test if positive is positive). And it is a very simple test.
All you need to do is play a known input signal called “Speaker Pop".
The following picture shows the wave form of a speaker pop track (Courtesy Studio Six). The entire waveform is above the zero crossing. There are no values below the zero crossing at all. When you are playing this track in your audio setup, there is only voltage on the positive (+) wire and nothing on the negative (-) wire.
Sharp minded readers will recognise this waveform as a simple digital pulsating direct current (DC). DC basically means always positive while AC (alternating current) switches polarity over time.
When you are playing this track, your drivers only move forward from rest (0), and from forward back to rest again. In layman terms this means you’d literally see the driver ‘popping out’. Confirm your drivers are doing this, this means your speakers are in phase.
If your system is phase inverted, your drivers will be ’sucking in’ instead of ‘pushing out’ when playing this track. If you see this, your setup is out of phase.
So do you get the joke now from the first page? Notice how everything seem to be drawn into the speaker rather than blown away like the classic picture? It’s a reference the drivers are sucking in more than it’s pushing out.
In general phase issues that are audible tend to be caused by mid-range and sub-woofers. Just confirming these two should be enough. For testing tweeters’ phase you’d require an iPhone. Also, I think it’s possible for tweeters to be wired 180° out of phase with the woofers. So do not be worried if your tweeters are not in phase as it’s the biggest drivers we are focusing here.
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