Hybrid Audio Technologies Legatia - Manual (Page 57)

Legatia User’s Manual ©Hybrid Audio Technologies Page 57 of 65
• A combination of ITD and IID are dominant for frequencies between approximately 500 Hz and
2,000 Hz; and
• IID, in concert with HRTF, are dominant above about 2,000 Hz.
These are generalizations, and are subject to the size and shape of one’s head and torso, and size
and shape of the outer ear (the folds and ridges of the ear), but in general, the above is a good
guideline for establishing ITD, IID and HRTF thresholds for the human auditory system.
Because the Legatia midbass’ ability to play into the sub-200 Hz range, an effect clearly dominated
by ITD, up to and including frequencies exceeding 6,000 Hz, an effect clearly dominated by IID and
HRTF, placement of this driver is extremely important. The driver should be placed as far forward as
possible in the vehicle to optimize ITD. Lateral (forward to back) placement is much more important
than horizontal placement (up and down). This is because of the brain’s ability to process sounds
such as spectral envelope cues, and use a phenomenon known as the “precedence effect”; the brain
can be easily “fooled” into thinking a sound stage is high with kick panel or floor-mounted speakers (a
word to the wise: the best place to put a set of speakers is not always “up high”, as most vehicles do
not offer an amicable location in the dashboard or a-pillars for good image placement for both seated
passengers, especially in the critical frequencies sub-500 Hz). In addition to the time equalized
placement of the drivers, the end-user must also consider that above approximately 2,000 Hz,
intensity plays a key role in good sound staging and imaging. Therefore, the Legatia midbass’ should
be placed in an area where intensity differences can be equalized, either mechanically or
electronically, to ensure good imaging and sound staging.
The lesson to be learned is that, like Lesson Two, the Legatia midbass should be placed as far
forward from your listening position as possible, and every effort should be made to optimize time and
intensity domain characteristics of the installation.
Lesson Four: Point-Sourcing
The term “point-sourcing” is often used to describe the technique of having a single pair of speakers
in an installation cover the majority of the critical middle band frequencies. In many installation
scenarios, the Legatia midbass could be considered a point-source speaker driver, because it has the
ability to reproduce six octaves of tones. Point-sourcing, if done correctly, can lend itself to a variety
of valuable attributes, including precise image definition and stable sound staging character. By
applying Lessons 1-3 above, the Legatia midbass can be used as a point-source driver to achieve
excellent staging and imaging results.
The lesson to be learned here is that the Legatia midbass, given its wide-bandwidth design, can
faithfully reproduce as much as six octaves of tones, and would make a valuable addition to any
sound system as a point-source driver for the spectrum comprising vocal imaging cues.
Lesson Five: Reference
One of the most important things to do before completing your Legatia installation is to get a
reference for your future listening tests. To really know what a snare drum sounds like, you must go
and listen to one, in person, live and un-amplified. There is no substitute for the visceral impact and
emotion of live music. Nothing else in life can touch your soul the way music does. Whether it’s a