>>>>I think with synthetic music you pretty much have to do it intentionally, in which case you probably want the sound. I mean it's not necessarily bad.<<<<
Not necessarily true, although a "real recording" (with microphones or live instruments DI'd with microphones as well) certainly create more opportunities for phase issues. Anytime you have stereo sound, and doubling/chorusing, or the ever-elusive "wideness" that everyone is going for today, you have the possibility of phase problems. And of course, the other kind (as posted above)-- your speakers could be wired wrong as well.
>>>>For example lots of people are mad about constructing bass drums from layers, that could (almost certainly will) introduce phase weirdness but if that results in a drum sound that works then the phase cancellation / doubling might be contributing to it working.<<<<
I get what you mean. But if those bass drums are hitting at the same exact time (let's call that point "0"), then you will not have any phasing issues per se. BUT, you can create problems with all of that low frequency, whether it be phase-based or just not enough definition because you need more "EQ carving" due to all of the competition for that same freq. range. But yes, there is also a "desirable" range of phasing/comb filtering that occurs when you say, double a vocal track and pan it wide L & R, and set them off from each other a few clicks for "thickness." The questions are 1) Does it sound good to you? and 2) Does it still sound good to you in mono? Mono is the great arbiter. And before anyone says, "Yeah, but nobody listens in mono anymore!", I would say, "Hold on there, lil' buckaroo; there's plenty of mono out there in the wide world." Whether it's your music being played by a DJ in a live situation, or your backing track being used in-concert/in a club for an artist to perform with, your music over a live PA in between acts at a show, or in the bathroom at that club, at the gas station or in other retail promo settings, on a ear-bud-less iPod, or just about anytime someone steps far away enough from a stereo image, or out of the room when they can still hear the sound-- Bingo! Your track is in mono. And that is where the phasing issues really appear, as your big-fat-wide whatever tends to disappear or just sound like cheese-y crap when it folds into mono.
So, always check it out in mono and if it's good to go, you're good to go. Some people prefer to start their mixes in mono, only moving on from relative volume and EQ to stereo imaging, _after_ they have checked-out the mono mix.
If your monitor controller has a "mono" button, you are golden. Then it's easy to check it every once in awhile and move on. If not, you need to set something up to monitor your summed content on, whether it be one of the Auratone/Avantone mix cubes, or a single PA speaker, or a single monitor you have set-up for that. Before we got the current speaker control unit we have now (that has a "mono" button), I had one of these with a mono feed just so we could bounce back and forth (ok, can't find the Yorkville, but here's one sort of like it):
Galaxy Audio MS5 Micro Spot 5 Passive Personal Monitor .
GJ