Apollo Installation 2
After some hiccups, the speaker is finally ready to test run and setup. With Acourate and digital crossover, it is rather easy to play around with different setting. The speaker is originally design to crossover at about 1.5K to get a getter dispersion pattern. This is a good concept in traditional speaker design and stereo reproduction. But since I use BACCH, it is better to have 1 driver to cover the mid range so as to reduce the phase issues at the crossover frequency. A good dispersion pattern in not necessary and in fact not good for BACCH. A narrow directivity is more helpful. The original choice of driver is already cater for this. The 5 inch c-quenze can easily go up to 7Khz without any strain! In fact, I am now crossing it at 6KHz.
Various crossover design has been experimented on and for those who know me, knows that I like linear phase filter design. With my last speaker, I chose Bessel’s filters. The problem with Bessel filter is that it is quite shallow so there is a lot of overlap between the drivers and that lessen the effect of BACCK over the XO frequency band. I finally decided on using NT filter. Linear phase and with steep slope. The drivers blend in very well too!
The setup and test with driver linearization, time alignment and level matching were described elsewhere on this blog and I basically followed the same route. Took me the whole afternoon to do that but the results are truly amazing!