I recently received a question in my inbox:

In passive crossovers, many are phase incoherent,
meaning that the phase shift of one frequency will be different than another frequency.
Do you agree?  Am curious how this is dealt with in the active crossover’s of B&O products?

At first, I debated just sending a quick email back with a short answer saying something pithy. But while I was thinking about what to write, I realised that:

• This is actually a really good question / topic
• I haven’t posted anything about crossovers in a long time
• I’ve learned a lot about crossovers since the last time I did post something
• I still have a LOT more to learn about crossovers.

As a result, this will be the first in what I expect to be a long series of postings about loudspeaker crossovers, starting with basic questions like

• Why do we use them?
• What do we think they do?
• What do they really do? and
• How are the ones we implement these days different from the ones you read about in old textbooks?

As usual, I’ll probably get distracted and wind up going down more than one rabbit hole along the way… But that’s one of the reasons why I’m doing this – to find out where I wind up, and hopefully to meet some new rabbits along the way.