It allows signals at some frequencies to pass through it more easily than others. You need a sealed box with Qtc less than .6, a woofer with Re/Le greater than 10,000 and low Qms. It’s called a DBX Driverack PA+. Even though it’s Digital, not Analog like Paul mentioned earlier, that he prefers. Many a producer such as Rick Rubin use Legacy Audio designs exclusively to master their recordings. I have an audio buddy who has a set of speakers with active amps and crossovers built in to each speaker . There are as many channels as amplified voices/instruments. Funny you say this. Variations in phase response on and off axis They work for a while, but develop listener fatigue in professional acoustic musicians and people who attend acoustic concerts regularly. My stage systems are analog mic signal to DSP crossovers driving linear amps so there is only one A2D and three parallel DACs in the chain (woofer, mid, tweet). Each channel is separate, no mixing or panning. These are placed in the same locations that work for the physical instruments, and sound the same – so much so, that conservatory trained string players can’t tell when we are using them to amplify. The 3-in is nice. "Crossovers? This requires a multi-channel DAC. It is too easily assumed that with an active crossover, driver-in-enclosure parameters drop out of the equation. An electronic crossover is different than an EQ. They have good A2D and DAC chips, mediocre opamps, capacitors and layout. There are equalizers and there are crossovers. The technical and aesthetic success of my music salon comes from integration. You can also go back and forth quickly and listen to the changes from a distance. There design is tall and bent at the top towards you. Equalization has many uses. You have to compress, fit channels in to different parts of the spectrum by cutting bass or treble, etc. I hope to play with this when I get time. But after much experimenting and reading I soon became adept. The high end audiophile market has successfully been convinced that active crossover networks and active equalization are degrading to performance. I’m using the DSP plug-in for JRiver and it seems to work fine. The individual crossover filter types (Butterworth,Bessel and Linkwitz-Riley ) with selectable roll-off characteristics from 6 to 48 db/octive, One is always welcome to stop by and say hello, call, or email and the Legacy guys are always there when you need him. Henry Kloss was as far as I know the first one to use a combination of passive equalization and a frequency separation for drivers in a crossover network. Inadequate bass leakage – roughly half the area of the smallest wall in windows, open doors, halls, stairways, etc. Now how would I synq two together so that i could get stereo 5 way? I have known about the deqx but dimissed it out of hand because it said it was only a 3 way, but upon closer inspection, it can do 5 way mono. But shouldn’t the guys serve to the endusers? It’s great becoming a member of the Legacy Audio family. Then it was time for my current speakers, the Legacy V’s. Separating subs causes phase problems, and grouping them exaggerates room modes. I found the GUI straightforward to use. Without this technique, those technologies would not have worked and by audiophile standards they are severe, up to 40 db at the audible frequency extremes. They probably cause listener fatigue in the general population, but all the other sources of fatigue mask the effect! My problem is meshing the sub to the mains which is a little difficult when the mains are running full range and the sub is being cut off at a steep slope. In the majority of active loudspeakers, the electronics sit behind the drivers inside the speaker cabinet. This means the maximum dimension is under 24″ so you can make accurate cuts on a standard table saw, and still have structural integrity and good seal. - George Carlin