Hybrid Audio Technologies Legatia SE - Manual (Page 9)

Legatia SE User’s Manual ©Hybrid Audio Technologies Page 9 of 73
Mms: The total moving mass of the speaker including the small amount of air in front of and behind
the cone.
Cms: The stiffness of the driver’s suspension.
Rms: The losses due to the suspension.
The Thiele/Small Response parameters are:
Re:
The D.C. resistance of the voice coil measured in Ohms.
Sd: The surface area of the speaker.
Fs: The resonant frequency of the speaker.
Qes: The electrical “Q” of the speaker.
Qms: The mechanical “Q” of the speaker.
Qts: The total "Q" of the speaker.
Vas: The volume of air having the same acoustic compliance as the speaker’s suspension.
Application to Thiele/Small Parameters to Legatia SE Designs
Enclosure Recommendations
The mechanical and electrical parameters of the Legatia SE midrange and midbass drivers are
amenable to a variety of different installations and speaker locations. In a typical vehicular
installation, Hybrid Audio Technologies recommends that the Legatia SE drivers be placed in an
“infinitely large” enclosure, which is more notably known as “infinite baffle.” Small sealed enclosures
are not needed to be constructed, nor are typically recommended in most circumstances for any of
the Legatia SE range of products (there are some minor exceptions, based upon application,
intended use, power handling, and etc., please contact us for details). Hybrid Audio has also had
great success incorporating the Legatia SE midrange and midbass drivers in dipole configuration
(detailed below), transmission lines, and in larger vented enclosures.
In a typical installation, Legatia SE midrange and midbass products should be mounted 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 that you contact us for details and
assistance in targeting a sealed enclosure volume applicable for your intended purpose. In all cases,
the use of loosely-packed fibrous damping materials, such as fiberglass, Dacron, or long-fiber wool