Pass Labs First Watt B5 Active Crossover/EQ for Open Baffle Speakers
The B5 is an active crossover and has been made sufficiently adjustable to operate with a wide range of open baffle designs and different drivers. It can also be used with more conventional enclosures and a wide range of different power amplifiers.
It features a two pole (12 dB/oct) low pass filter variable from 20 to 300 Hz in 20 Hz steps, and a high pass filter with 1 or 2 poles (6 or 12 dB/oct) which is also variable from 20 to 300 Hz in 20 Hz steps.
The woofer channel also has a 2 pole high pass filter for the woofer with a 6 dB equalization “bump” at 20 Hz. This is useful for extracting a bit more output at the bottom of the audio range of any loudspeaker, particularly open baffles, and functions as a subsonic filter below 15 Hz.
The full range high pass channel offers choices of shelving equalization curve (also known as “baffle step correction”) for full range drivers, variable from 250 Hz to 2.5 Khz with shelving at 0, -2, -4, -6 and -8 dB.
The active circuits are JFET buffers, most of them simple source followers without feedback. The distortion and noise are quite low, and the bandwidth is very wide.
You can download the B5 Manual in pdf format.