Originally Posted by dazzdax
Thank you all for the nice words regarding system set up.
The 100Hz crossover point I chose deliberately to prevent extreme forward and backward movement of the electrostatic membrane during loud low frequency passages, so I can play louder (more SPL) without the risk of damaging the membrane.
If I would choose 70Hz as crossover point I'm afraid the membrane is still making quite large movements.
Why do you prefer 24Hz instead of 12Hz? I was told that a 24Hz slope gives more phase shifts than 12Hz slope?
"Hz" is a unit of frequency, the crossovers under discussion have slopes of 12 or 24 dB/octave. Note -10 dB is about half as loud to us (humans), and requires 1/10th the power. 20 dB is a factor of 100.
For most filter designs phase does shift more as the filter order (and thus rolloff) increases. However, in a speaker system what really matters is that the two speakers are in phase (move together) right at the crossover point. Away from that point, the "off" speaker is being rolled off and contributes less and less to the total output, so phase does not matter. Note Rythmik subs include a continuous phase control so you can dial in the phase match at the crossover frequency (a simple 180 degree switch is generally not enough).
I prefer to roll off quickly to prevent out-of-band signals causing distortion and higher power peaks in the sub and mains. There is a lot of energy in the 60 - 120 Hz band so I was suggesting a faster rolloff to your A-1's might help better integrate the subs while still reducing the LF energy into the A-1's. You'd have to try and see; it depends on the music and/or movies you watch, how loudly, etc.
A Linkwitz-Riley design essentially cascades two (Butterworth) 2nd-order filters to provide 4th-order response, i.e. 24 dB/octave rollof. That scheme provides the same phase, and if gains are matched a flat amplitude through the crossover region (many other designs are possible but many do not provide flat electrical amplitude and phase through the crossover region). That is what I use in my system.
HTH - Don