Well along with taking some time for my wife's birthday, the weather here has continued to be unseasonably nice and I needed to cut some lawn, resurrect the deck gazebo and do some power washing. With all of us vaccinated, it was the first time my family has been together since last summer. The last couple of days have had some rain, so I got back to my hobby and worked on Directiva...
Have been working on amplifier alternatives and still looking for something to help make it more affordable. Currently, the best option seems to be the Hypex Fusion amps, but have not bought any as yet. The only other cheap amp I have around is a Dayton APA150. Am going to swap it in and see how it compares to the current Hypex NC252MP. Notably, am interested in whether it may be noisier. As for the speaker, had to recalibrate my test stand to ensure I could reproduce my earlier results. This was done readily and I started to use the other configuration profiles in the minidsp to test lower crossover points.
I did a quick check at 1600 Hz and quickly saw I needed to look over the individual driver performance again. The simple set the driver to the same crossover frequency and LR24 slopes was not working. The main issue is the tweeter low-end rolloff and the LR24 now produced a steeper acoustic slope, This investigation would be better modeled in VCAD, so I left it to later. I did play with a little lower crossover and found that 2200 worked as well as 2400 Hz. Here are some measurement results from that round. So, first, let's revisit the on-axis performance...
Should look familiar, and if it does not, take my word it is almost identical to the 2400 Hz crossover. This should not be too surprising as both frequencies are roughly in the middle of the driver's overlapping responses. The main reason to push a lower response was that I had seen some distortion issues with the woofer at higher output levels. So, decided to check. Here is the distortion at about 80 dB...
This looks pretty good and so decided to push the design considerably harder. So, here is a look at 95 dB...
Clearly something going on around 400 Hz that might warrant further investigation, but pretty good overall and none of the 2-3 kHz ugliness I had seen earlier. For the sake of simplicity, may just forgo any attempts to lower the crossover point unless directivity or another issue suggests a need to reconsider.