L212 and B212

[Zilch]

O.K., I'm confused.

L212 system comprised two 3-way towers and a powered subwoofer.

There's references here to a B212 crossover. Is B212 the sub, and it had a passive crossover after the amp?

[Reserves right to delete question if it's REALLY, REALLY stupid....] ;)

[4313B]

Definitely not a stupid question. The B212 "crossover" is simply a two pole filter that comes before the 75 watt amp that is bolted into the bottom of the B212 enclosure. According to the literature, it rolls off the B212 at ~ 10 dB/octave above ~ 70 Hz. This can be misleading since JBL doesn't set the voltage drive to necessarily be -3 dB at the intended crossover frequency. The actual filter really starts rolling the bass amp off around 50 Hz so that the acoustic crossover between the B212 and L212 satellites does indeed occur at around 70 Hz. The high pass filter for the satellites consist solely of the sealed enclosures for the 112A/112H 8" midbass drivers. Sealed enclosures are ~ 12 dB/octave high pass filters.