What I know about the Lambda is the low LE must make a big diff in detail. Thinking about the choke of a power supply reducing ac ripple, the LE of a driver, if low, does not reduce the ripple of the signal coming into the driver. Might be dead wrong about this, but it seems to make sense.
It makes a
big difference in the transfer function of the crossover because the load is more resistive. Most woofers need a Zobel or there's a big peak around the crossover frequency. See page 43 of my
crossover document and page 14 of the
schematics lab handout for my "Crossover Electronics 101 seminar". The
formula handout from the "Crossover Electronics 101" seminar is pretty handy too.
Anyway, you'll notice in those handouts that the Spice models show a 10dB to 14dB peak around the crossover frequency on most woofers using a second-order (or higher) crossover. This is seen in the measured response curve too. At the Crossover Electronics 101 seminar, we examine these circuits on paper and then play music through these exact circuits connected to speakers. You can
really hear that peak, it's huge.
The peak is caused by voice coil inductance and its interaction with the passive crossover. Basically, it makes the filter "see" a load higher than it was designed for, so it's underdamped at higher frequencies. The solution is usually a conjugate filter, in this case a Zobel or RC damper.
The AE woofers are fairly unusual, as they present a mostly resistive load, even at the relatively high frequencies required of them as a midwoofer in a DI-matched two-way. When I first designed with them, I expected to need much smaller capacitance in the Zobel, but I didn't expect to omit it entirely. But that's how it works best, at least in my case. I expect the same for your efforts here, because the speakers you're building are functionally very similar to mine.
The link below describes my design process for loudspeakers like these, and in fact, shows a crossover schematic using an AE TD12S woofer and DE250 compression driver on an H290 horn. You'll notice in the schematic, the builder can choose between an AE TD12S woofer or an Eminence 12LF, and the difference between them is mostly the presence or absence of the Zobel.
