I built a "Bassis" about two years ago. I upgraded the op amps. I use it to push a 18" SW in a sealed box down below 32 hz. If I ported the box I could have gotten well below 24 hz. but then I would have to deal with port problems. So I went with electronic EQ.
Anyway, yes it works as claimed. My only negative is with some disks (1 or 2 out of several hundred) the low freq. rumble is too great and I need to bypass the SW.
I also have a Marchand Tube Xover and his 300 watt amp (that I use to drive the SW). Overall I am happy with all my Marchand purchases. Plus, I have found that his after sale support to be good. Hope this helps.
Anyway, yes it works as claimed. My only negative is with some disks (1 or 2 out of several hundred) the low freq. rumble is too great and I need to bypass the SW.
I also have a Marchand Tube Xover and his 300 watt amp (that I use to drive the SW). Overall I am happy with all my Marchand purchases. Plus, I have found that his after sale support to be good. Hope this helps.