Set-Up Considerations and Installation
Legatia L3 Enclosure Requirements
The Legatia L3 is an infinite baffle-capable speaker, and must be mounted in an “infinitely
large enclosure” with unrestricted access to airspace to ensure the speaker’s ability to
effectively reproduce its wide frequency bandwidth. The reason why the speaker was
designed in this way is highly empirical. When a speaker is mounted in a small closed box, it
radiates as much energy forward of the cone as it does rearward of the cone. All speaker
cones and dust caps (diaphragms) are a weak sound barrier at best, and the result of the high
amount of energy being “pushed” into a small enclosure is the energy transmitting through to
the outside of the cone (an additive phenomenon to the incidental wave). It is conjectured
that this effect is most notable in the low hundreds of Hz region, where acoustical stuffing
materials are ineffective and the internal dimensions are not small enough for the internal air
volume to act as a pure compliance. Consequently, Hybrid Audio has designed this speaker to
work well without an enclosure, and as such, should not be significantly prone to enclosure
back-pressure and sound coloration when placed infinitely baffled. The “infinitely large”
enclosure, per se, improves spectral response and power response variation between high and
low frequencies. And in the case where an infinite baffle operation is difficult or impossible to
achieve in your car’s environment, we highly suggest the use of acoustic resistors (aperiodic
membranes or trade name Variovents
®
) in sealed enclosures to help dissipate the backwave
energy. If you absolutely must use a sealed enclosure, we recommend a volume of at least
2.5L. Hybrid Audio has also encouraged the use of transmission line enclosures for the L3’s,
and has seen great results with TL’s “tuned“ to between 120 and 150 Hz to work extremely
well in the car environ. In all cases, the use of loosely-packed fibrous damping materials, such
as fiberglass, Dacron, or long-fiber wool will also significantly improve the final installation, no
matter what type of baffle and enclosure configuration is chosen.
While infinite baffle or resistive sealed enclosures are highly recommended for this driver, you
might find that in the rare instance the L3 driver can be placed in a completely open baffle, i.e.
dipole. A word of caution: an L3 mounted in an open baffle has to move more air than an L3
in an infinite baffle, just simply for the fact that there’s a progressive acoustic short circuit
between front and back below the speaker’s Fs in the open baffle configuration. Great care
must be taken in this instance, because there is no acoustic compliance afforded in a dipole
configuration, and the speaker will reach its mechanical limits much quicker (and will net
increased distortion). However, in certain instances, a dipole-style midrange may work well in
a vehicular installation, in that radiation from the rear of the baffle, having undergone enough
phase shift as it comes around to the front, adds to the total sound at off-axis angles. Of
great importance in the dipole midrange configuration is the setting up of crossovers and
weighing the negative effects of distortion of elevated amplitude levels.
Legatia L3 Mounting Baffle Requirements
The baffle that the Legatia L3 is mounted in should be small in dimension if at all possible.
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
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