4TH ORDER LINKWITZ RILEY LOW PASS
Figure 28, the upper curve is the PL18 without any crossover.
The lower graph is a Gated SPL Sweep of the PL18 with the
difference in SPL is due to some additional equalization circuit
which we shall ignore for the time being. What is of interest
is the rate of rolloff.
simulation, it's supposed to be 24dB/oct. Acoustically, it
was measured at 17dB/oct.
28) 4th Order Linkwitz Riley Low Pass
ORDER LINKWITZ RILEY HIGH PASS
to Figure 29, the top graph is of the PL27 without crossover.
lower curve is a Gated SPL Sweep of the PL27 with crossover
together with a L-Pad and a Notch Filter to neutralize the
free air resonant impedance peak.
Rolloff is measured at 18dB/oct.
29) 4th Order Linkwitz Riley High Pass
can conclude that our earlier Spice modeling of the networks
is not an accurate reflection of the true acoustic response
into a resistive load, it was at 24dB/oct. When the same crossover
is connected to a driver, acoustically it rolled off at about
should therefore, be careful not to make the assumption that
a crossover modeled to rolloff at 24dB/oct electrically, will
rolloff the same acoustically.
30) 4th Order Linkwitz Riley Low Pass with High Pass