Hybrid Audio Technologies Legatia Pro - Manual (Page 36)

Legatia Pro User’s Manual ©Hybrid Audio Technologies Page 36 of 43
good-quality, brand name self-adhesive damping product; a solid wood mounting baffle with sound
damping treatment will augment the Legatia Pro installation by eliminating resonances.
Mounting baffle dimensions: While building baffles is important, it is notable that mounting baffle
size is equally important. All mounting baffles should be kept as small as possible with respect to the
size of the speaker. The purpose of using a small baffle is to avoid the potential for low amplitude
diffracted sound waves becoming summed with the incidental waves. A narrower baffle also becomes
increasingly important as frequencies range into the Legatia Pro midrange’s upper bandwidth, where
the power response is more uniform and incident and reflected waves are indistinguishable. In
practical terms, keep baffle dimensions small with respect to the size of the Legatia Pro midrange,
chamfer or round sharp edges, flush-mount the speaker whenever possible, and use shallow,
surface-mounted hardware (or ideally use the supplied knurled attachment nuts). Also, remove all
unnecessary protrusions from the baffle surface.
Crossovers
One of the most fundamental and important considerations in the final tweaking of a car audio system
is the set-up of the speaker’s crossovers. The Legatia Pro drivers use fine cloth diaphragms that
exhibits little if any cone breakup in its upper frequency bandwidth. However, it is still important to
utilize crossovers, especially active crossover networks to suit the speaker system to the car’s
acoustic signature. It has been Hybrid Audio’s philosophy to tune the speaker system to the vehicle’s
acoustic signature using just active crossovers, and only a very minor amount of equalization. Our
very best world championship vehicles have always had one thing in common: creative use of active
crossover filters and very minimal equalization. Use your crossovers to tune your car, and the
equalizer to suit the vehicle’s speaker response to your own tastes.
The first thing to remember is that every speaker exhibits some sort of a natural roll-off. This rolloff
typically amounts to about 12 dB/octave, and needs to be taken into account, especially when
designing passive crossover systems (this roll-off has been accounted for in the Legatia L2x and L3x
designs). Simply adding a capacitor and inductor in series (6 dB/octave bandpass filter) to a Legatia
Pro midrange driver does not necessarily mean that you’ll see a phase coherent 6 dB/octave
bandpass filter at its crosspoints. In fact, summing the effect of the driver’s natural bandpass roll-off,
you might actually be approaching a theoretical 18 dB/octave bandpass filter at certain frequencies.
Not only this, but the speaker could potentially begin to exhibit significant intermodulation distortion as
the cone becomes non-linear trying to reproduce the lowest octave of tones, not to mention irregular
polar radiation patterns between the Legatia Pro midrange and the accompanying Legatia Pro
tweeter.
Given the large uncertainty of low-order crossover systems, Hybrid Audio recommends the use of
higher-order electronic crossovers so that fine tuning can be done electronically. The active network
benefits from easy correction of different speaker sensitivities and equalizing not only the individual
drivers but the combined response as well. Not having to account for the speaker’s impedance
verses frequency, as well as the passive device impedance and phase shift makes the active filter
superior to most passive crossover networks, due to the fact that each and every aspect can be
tailored to better suit the individual installation’s requirements. However, we understand that in some
cases that passive filters are required, and thus the reason why we have manufactured the Legatia
L2x two-way and Legatia L3x three-way passive crossover systems. In our humble opinion, however,
the ideal crossover system for most users, is an active one that takes into account the Legatia Pro