In Part 1 we looked at what we really mean when we talk about phase and polarity - now let’s look at some real life examples. It’s worth to note that although we often talk about “fixing” them, phase and polarity are not really the bad guys - they are just part of what happens whenever we add more than one source of sound together.
Phase and polarity of a single sound.
Let’s start simply and record one guitar, one amp, one speaker, one microphone and no reflections, so that we have a clean, single signal.
Phase can get fairly complicated fairly quickly (Google “Phase Shift” and “Group Delay” if you can’t sleep some night) because moving a microphone a few millimetres will make a small difference to an open low E string of a bass (where 10mm is equivalent to just over 0.4 degrees phase difference) but much more to the 24th fret of the high E (where 10mm equates to just under 14 degrees), so a sound that’s made-up of more than one frequency WILL change absolutely with mic position (which we already knew). Once that sound has been recorded and we nudge the track forwards or backwards, we’ll just hear it as playing slightly earlier or later until we have another track to compare it with.
Bottom line; put the mic where it sounds good and then don’t worry about it.
Two mics on a single source
Now let’s put two mics onto our cab.
Two mics on a single source – opposite directions
Obviously, all of the examples we’ve considered apply to anything where we might have more than one mic (or DI or trigger or pickup) for a single instrument, voice of source. When I first started recording I thought I understood that reversing polarity of a track or two would give an obviously “better” or “worse” sound. Examples in tutorials (often using sine waves) always seemed to be completely clear-cut, and I couldn’t understand why I rarely found a completely obvious ”right way”. Later I tried various phase shifting plugins and nudging the positions of tracks on the timeline in my projects, and still it didn’t seem to be as “night and day” as I expected. Ultimately, the moment we move away from recording a single-frequency, reflection free, symmetrical wave – we run into phase considerations: it’s basic Physics, and Physics doesn’t care about making our lives easy. The answer is to be aware of it, then don’t worry too much, and stick with Joe Meek; “If it sounds good, it IS good!”
Next time, we’ll take a look at handling phase issues from bleed from multiple tracks. Deep Joy!