Here is the results of my first experiments with active crossovers. (Rane AC 23 B, five way) with 2404H added to my 4435
I set the high crossover frequency at 7 Khz( it's the highest possible on the Rane), put a measurement microphone at 1 ft from the the front baffle, midway from the center of the two horns ( the 2404h was positionned on the top of the cabinet, insulated with acoustic foam and aligned vertically with the 2344A.
The rane crossover comes without CD compensation (it can be done internally), and I don't Know if this compensation is done by a slight parametric equalisation or othewise. Thanks to Robb if he Knows what it is exactly.
The measurement microphone was connected to a real time analyser, emitting pink noise (1/3 octave filtered)
The level produced by each driver separately was set at 80dB Spl at 1 Ft.
Whith the two drivers emitting, I got +3 db Spl with a slight adjustment of the delay control of the 2404 H on the Rane crossover.
I got the same level with no delay on the crossover, simply by moving the 2404H slightly backward. The frequency response curve displayed on the RTA (resolution 1dB was flat(+or - 1dB) between 2Khz and 18kHz with a slight rolloff after 18 kHz(which can be compensated by adjusting the level of the 2404H, not necessary in my opinion).
I proceeded in the same way with the 2426H and the medium 2234H .
No delay adjustment needed as they are aligned by construction. I only had to adjust the level of the 2234H.
Now between the two 2234H, the delay adjustment is inoperative to compensate differences in response level as they are horizontally positionned. Anyway, when using an amplifier for each 2235 (one from 30 Hz to 100Hz) and the other from 100Hz to 1kHz doesnt not co rrespond to the original setting, where both drivers starts at around 30 Hz. And with the Rane crossover it is not possible to have such a setting.
The result was a losss inlevel in the bottom end.
I then added a Velodyne HGS 18 sub( from 20Hz to 70hz), under the 4435 and set the crossover frequency of the low 2234 at 70 Hz) The overall result was a flat response curve from 20Hz to 18500 Hz) The 4435 are mounted at 3 feet high, in order to have the have the drivers emitting over my recording console.
Now at ten feet from the monitors, atears'height behind my console the frequency response curve is nearly flat,at 80dB Spl level, but I have still a lot of work to do to improve the acoustics of my control room.At higher levels, the things are different I think that there are several things to experiment, as the Rane crossover are Linkwitz Riley type with 24dB/Octave slopes. I'll try the same experiment using Behringer DCX 2496 or BSS FDS 366 crossovers, on which it is possible to choose the filter type ( Linkwitz, Butterworth, Bessel) and slopes from 6dB/octave to 24dB/Octave. If any member has already done the job, I would be glad to know which type of filter suits the best.
Thanks to everybody
Squirrel