The problem is less about the terms themselves and more the areas where they may overlap complicated by casual, less than fully precise usage.
- Active vs. passive refers to crossover approach implemented in a multi-driver speaker (with subsequent impacts to the amplification approach)
- Active speakers have a line-level cross-over upstream of the amps. (Requires more amps, but typically smaller.)
- Passive speakers have a speaker-level crossover downstream of the amps. (Requires fewer amps, but typically larger.)
- Active vs. passive in no way defines the crossover implementation - it can be analog or digital.
- Active vs. passive in no way defines where the amps or crossover are installed - they can be inside the speaker or external.
- Multi-driver speakers can be partially active. (Most commonly the mid-to-bass crossover will utilize an active crossover, as the large voice coils of these drivers produce the most significant back-EMF. The bass driver in this scenario could just as easily be a subwoofer as an integrated woofer.)
- Single-driver speakers do share one of the primary benefits of active speakers, mainly a lack of back-EMF transmitted through a crossover from one driver to any others, impacting the impedance response of all connected drivers. (Back-EMF complicates the crossover design, but can be addressed by a good designer.)
- Single-driver speakers may be implemented with frequency response correction (EQ), which is typically included as part of the crossover design in a multi-driver speaker. This could be done before or after the amp, either via analog or digital means.
- Powered speakers have the amp integrated into the speaker itself, which can then have either an active or passive crossover, or no crossover at all, as well as analog or digital driver EQ, or none at all. It implies nothing about how the signal is managed.
I don't recommend trying to co-opt terms used to describe crossover implementations as a means to highlight a single-driver speaker design benefit that just happens to be shared in common with one particular crossover approach. The 'single-driver' description already implies the lack of back-EMF that you're trying to acknowledge. There is no 'passive' version of a single driver speaker from which to try and differentiate.
Focus instead on understanding how the design compromises differ in a single driver implementation vs. that of a multi-driver implementation and the various ways in which they may be overcome, and then just be able to explain it while adding the correct details to your single-driver speaker description if you feel the need for added precision. Examples:
- If your amp is integrated into your single driver speaker, call it a 'powered single-driver speaker'.
- If you want to characterize the driver EQ description, call it a 'single-driver speaker with analog (or digital or no) driver EQ'.