L3x Three-Way
Passive Crossover
History
The Legatia L3x topology is loosely based off of the
Legatia L2x crossover topology. It’s no secret that
Hybrid Audio Technologies highly recommends the
use of active crossovers that are set-up and adjusted
by an industry specialist, such as a master tuner, or
a highly-qualified car audio shop installer (please
read any number of White Papers on the subject of
passive crossovers on the www.hybrid-audio.com/
downloads.htm web page). In some cases, however,
using active crossovers is not a viable option, so
we designed and manufactured the Legatia L3x to
allow for easy Legatia installations, especially when
multiple amplifier channels and/or adequate active
crossover processing was not available in the car
audio installation.
The L3x can be used for virtually any Legatia
three-way passively crossed-over systems, or used
in conjunction with other Hybrid Audio products to
create a truly “bespoke” three-way system.
Key Issues in Passive Crossover Design
Before highlighting the L3x’s design attributes, there
are certain key issues in passive crossover design
that the end-user should be aware of. For years,
vocal manufacturers have coerced the consumer
into believing that capacitors, coils, and resistors
are not only desirable, but are a requirement. One
notable “high-end” speaker manufacturer boasts
that they spend “months” working on crossover
designs to ‘enhance’ their speakers. To ‘enhance’
means to add considerable filtering to fix speaker
response anomalies, aka poor speaker designs.
Our speaker design philosophy is to spend the
time and resources necessary to make the speakers
exceptional in the design phase, and then use
simpleton filtering to protect only for thermal
protection at resonance and provide the desired
frequency response. It is our philosophy that the
passive crossover should not contain any level of
equalization; none of our designs, in any series, use
crossovers that contain any form of equalization
beyond simple tweeter attenuation. We believe
in making the speaker great, not trying to fix
a poor speaker with filtering and attenuation.
There’s no crossover in the world that can make a
poorly-designed speaker sound good. This is why
there’s a relatively simpleton, high-quality crossover
topology employed on the Legatia L3x crossover,
with no additional board-mounted equalization.
And this is also why we implore you to use our
world-class speaker systems in concert with the L3x.
Attributes
The Legatia L3x is a bi-amplified three-way passive
crossover for use with virtually any midrange,
midbass and tweeter pairing Hybrid Audio
manufactures. The following are the L3x’s design
attributes:
Filter Set
The L3x is a bi-wired three-way passive crossover
that has the following filters:
Lowpass (midbass): 300 Hz at 12 dB/octave Linkwitz
Riley
Bandpass (midrange): 300 Hz to 6,000 Hz at 12 dB/
octave Linkwitz Riley
Highpass (treble): 6,000 Hz at 12 dB/octave Linkwitz
Riley
The only filtering on the board is mentioned above,
and in essence are elementary highpass, bandpass,
and lowpass filters common in any three-way
crossover design. As noted above, there is no
board-mounted equalization specific to one brand
or type of midrange or tweeter, or common of
competitor’s designs where equalization correction
(filtering) is added. The L3x can be used with any
number of drivers we produce.
The L3x passive crossover networks incorporate
asymmetrically arranged super high quality and low
tolerance metalized polypropylene film capacitors,
air-core inductors, and low tolerance non-inductive
resistors. Even the massive lowpass and bandpass
capacitors are super high-quality polypropylene
capacitors, nearly unheard of by today’s standards.
No output level switches were used in the passive
crossover design because switches add a resistive
effect and are typically of extremely low quality.
Additionally, “jumper pins” add an unnecessary
pair of splices in the signal path to the tweeter,
and were not included in our design either.
Rather, all tweeter level adjustments are done
on the board level with dedicated non-inductive
resistors; tweeter attenuation is accomplished
by selecting the appropriate output (-3 dB, 0 dB,
or +3 dB) on the passive crossover circuit board.
Likewise, midrange attenuation is accomplished
by selecting the appropriate output (0 dB or -3 dB).
The components selected are complimentary and
ensure no appreciable signal degradation between
the input and output side of the crossovers.
Likewise, the capacitors and inductors are arranged
on the board to reduce the coupling between
circuits and electromagnetic interference by basic
physical separation, while still keeping the footprint
size of the circuit board small. Finally, the use of
12 dB/octave filters on both low pass and high
pass minimizes phase-related distortion typical of
crossovers with mismatched orders, and ensures
relative phase-coherency.
L3x Cont’d on following page...
Although the Legatia
L2x is listed in the Stage
V Legatia series, it has
multiple complimentary
uses for Legatia Pro
products as well, given the
complimentary crossover
topology and use of
low-tolerance, asymmetri-
cally-aligned componentry
and lack of board-mounted
equalization
Legatia Pro
Speaker
Design
© Hybrid Audio Technologies • Cumming, GA • 770.888.8200
© Hybrid Audio Technologies • Cumming, GA • 770.888.8200
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