What do you think of passive crossovers – page 41 – diyaudio j gastroenterol impact factor

Be aware that "minimum phase" measurements which calculate the minimum phase response only from the amplitude response rather than actually measuring true phase cannot capture any relative time delay differences between the two drivers due to misalignment of the acoustic centres.

This means that unless the drivers do have their acoustic centres exactly aligned with respect to the design axis and measurement microphone, you won’t get valid phase information to allow you to get the phase tracking through the crossover region correct.

For example in my case where the tweeter is ahead of the woofer and needs the delay of the all pass filter the minimum phase responses would make it seem as if everything was ok and no all pass filter was required, when in fact that’s not the case and the phase is out by nearly 180 degrees at the crossover frequency due to the different time of flight between the drivers.

To get valid phase data for the simulation you also need the microphone height equidistant between tweeter and woofer (or on the design axis of you choosing, which some people make the tweeter axis) in the exact same place for both driver measurements, and either take the measurement in dual channel mode (where the 2nd channel is a loop back connection from the driver terminals) or use a sound card that has a very reliable, consistent processing delay from one measurement to another.

Some sound cards are just not usable in single channel mode for phase measurement because there are slight random differences in processing delay each time the sound device is opened that will cause random errors in the phase measurement. Even if the sound card seems good for single channel measurements you can never quite be sure whether phase errors are being introduced.

The only truly reliable way to get the phase measurement right is to use dual channel measurements where one input is the microphone and the other is a direct electrical sample from the driver terminals used as a reference for the cross correlator. With this method it doesn’t matter if the processing delay of the sound card changes from one measurement to another, it will be cancelled out. This allows for very accurate repeatable phase measurements. Dual channel mode also cancels out any frequency response errors due to the test amplifier or speaker cable resistance which is handy, provided the pickup point is directly at the speaker terminals.

It’s a bit more work to set up dual channel measurement and capture true phase, and requires a sound card that can input line level on one channel and microphone level on the other channel simultaneously (or an external mic pre-amp) but IMO you really do need to do this to get valid results for the summed response in a simulator.

If there is no "care" in crafting, one could spend a few cents on a electrolytic cap for a tweeter – oh wait, many speakers have exactly that. But it is not sounding good of course. Active wins on sound quality easily even when used with minimal amount of work.

Then one would phase align, fix a response peak here, a dip there, and get a pretty complex crossover, which may require e.g. a 12awg Litz air core to pull off, by that time it is pricewise firmly in audiophile territory. An active can easily offer the same level of complexity at a lower cost, even after accounting for extra channels of amplification.

There must be a break-even point, I think, where the cost of active vs cost of passive are the same. What I am essentially claiming is that the active will win on sound at the same cost, because active will always allow you to tweak the sound to your liking with a single up-front cost. (You can always put more care into active without increasing cost, but the same is not true for passive.) No one would realistically implement Linkwitz Transform passively, for example, unless you are talking about line-level passive.

Be aware that "minimum phase" measurements which calculate the minimum phase response only from the amplitude response rather than actually measuring true phase cannot capture any relative time delay differences between the two drivers due to misalignment of the acoustic centres.

This means that unless the drivers do have their acoustic centres exactly aligned with respect to the design axis and measurement microphone, you won’t get valid phase information to allow you to get the phase tracking through the crossover region correct.

For example in my case where the tweeter is ahead of the woofer and needs the delay of the all pass filter the minimum phase responses would make it seem as if everything was ok and no all pass filter was required, when in fact that’s not the case and the phase is out by nearly 180 degrees at the crossover frequency due to the different time of flight between the drivers.

To get valid phase data for the simulation you also need the microphone height equidistant between tweeter and woofer (or on the design axis of you choosing, which some people make the tweeter axis) in the exact same place for both driver measurements, and either take the measurement in dual channel mode (where the 2nd channel is a loop back connection from the driver terminals) or use a sound card that has a very reliable, consistent processing delay from one measurement to another.

Some sound cards are just not usable in single channel mode for phase measurement because there are slight random differences in processing delay each time the sound device is opened that will cause random errors in the phase measurement. Even if the sound card seems good for single channel measurements you can never quite be sure whether phase errors are being introduced.

The only truly reliable way to get the phase measurement right is to use dual channel measurements where one input is the microphone and the other is a direct electrical sample from the driver terminals used as a reference for the cross correlator. With this method it doesn’t matter if the processing delay of the sound card changes from one measurement to another, it will be cancelled out. This allows for very accurate repeatable phase measurements. Dual channel mode also cancels out any frequency response errors due to the test amplifier or speaker cable resistance which is handy, provided the pickup point is directly at the speaker terminals.

It’s a bit more work to set up dual channel measurement and capture true phase, and requires a sound card that can input line level on one channel and microphone level on the other channel simultaneously (or an external mic pre-amp) but IMO you really do need to do this to get valid results for the summed response in a simulator.