As a bassist and (sometime) soundman, I've experienced a LOT of polarity problems/phase issues. Most recently 2 have cropped up:
1.) (2)DNS 112-N cabinets delivered with reverse-polarity woofers installed- but NOT compensated for.
2.) Digital latency delaying sound enough to throw the on stage bass cab out of phase with the house.
There are few things that can kill your bass mojo faster than phase/polarity issues. Anyone else having issues like this?
As long as both DNS 112-N cabinets where in phase with each other, not much of a problem. If your worried about absolute polarity, simply flip the polarity at the board or DI and the problem is compensated for, but not typically dealt with in any effective way. Why? Mixing cabs with different tunings results in phase and group delay errors as well. It's likely your bass amp and the monitors and subs or mains are tuned different enough to cause problems even if the speakers are all in polarity and placed right next to each other.
Another problem is the separation or physical offset between like speakers producing the same sound causes phase problems. Consider all the monitors spread out across a stage. Depending upon where you are in relation to each monitor, it takes a different amount of time for the sound from the monitors to reach you. Stated simply, the sound can only be in phase for all frequencies if you are equidistant from each monitor.
So mix and match subs, monitors, and the bass amp, which are physically displaced from one another and have different phase and group delay characteristics. Yeah it's a mess, but the digital latency actually may help resolve some of the issued. Why? You can attempt to make some correction with delay. IE, delay the closest speakers back to the farthest speakers. This strategy is designed to improve sound for the audience, and may make things worse for the poor bass player. A philosophical decision is required on whether the performer or patrons experience should be prioritized. As a bassist and audio tech, I generally argue to favor improving the audience's experience, but there has to be a reasonable compromise since musicians need to be able to hear well enough to perform.
It's pretty common to delay the subs and mains to the backline, but unfortunately if you think about it, you realize delay cannot be used to get perfect phase alignment everywhere in a venue because the spacing between all speakers is not exactly the same. Basically you can only make a judgment call and adjust for the best possible compromise. I use a large tape measure to get in the ball park then dial it in with my ears. I usually walk the room a couple of times while making adjustments.
Crossovers also introduce phase errors, so pro-level system tuners typically use a program like SMAART to phase align speaker elements and time align speaker arrays for best results. A bit higher in the food chain than I exist, but I do find the theory interesting and useful.
Phase and polarity can also be your friend. Directional (cardioid) subwoofer arrays can be formed with physical offset, delay, and polarity. Also some degree of lobe steering is possible with precise delay adjustments between speaker elements.
