Last Saturday we had a measuring session for fury's (Danny) new DIY active speakers, shown above.
Rack includes a Tascam CD player, Behringer Ultramatch and two Behringer DCX crossover units, as well as an Altronics multi channel volume control below, a power conditioner/sequencer and three beefy Yamaha pro amps.
We measured the speakers outdoors on my rotating measurement rig.
You can see that it looks very much like a Geddes speaker. It features a BMS 4550 compression driver in an Autosound Oblate Spheroidal waveguide and reticulated foam that was cut by me. I have posted about this previously (a search will show previous posts). The midwoofer is a 12" JBL 2206H.
BMS 4550 compression driver + Oblate Spheroidal waveguide
The waveguide provides good control of dispersion even down as low as 600 Hz, below which point pattern control is quickly lost. There is some freedom here to cross low if desired. Above 15k the pattern narrows slightly.
This measurement was perhaps a little surprising in that the woofer measurements tended to indicate there was some flexibility with crossover point as well.
Measurement laptop + DCX + power amp + audio interface.
Black - response 22 degrees off axis
Red - axial response (note the diffraction dip around 5k)
Blue - the result of letting auto align mess things up
After some experimenting and measuring, a crossover at 900 Hz was chosen. We took some extra measurements to confirm that the filters were set correctly and ran auto align only to find that in this case it might be called "auto mis-align!" We used the EQ prediction capability of REW to work out the settings to EQ the top end, resulting in the flat response shown above. The axial response must not be used because there is a diffraction dip.
We ran out of time and didn't get a chance to listen with the new crossover settings, so we heard them without CD EQ applied. The midrange was clean and controlled and I could not help but feel that it was partly due to the 50mm thick cabinets as well as very good drivers.