Set-Up Considerations and Installation
conditions, and lose its liveliness. We don’t live in an anechoic world, so why try to recreate
anechoic conditions in our cars? Reflections are all around us, and are a part of our day-to-
day lives. It is our opinion that some lateral reflection is a good thing; it helps to establish
stage boundaries, and gives the recoded playback and more visceral and “believable” sound.
The first principle to understand is that below 200 Hz, acoustic treatments are rendered
virtually useless. It is Hybrid Audio’s assertion that only those frequencies above 200 Hz
benefit from the use of treatments, given that a 200 Hz waveform is about 1.7 m long; 1.7
meters is less than or equal to most vehicle widths. This is also the frequency where we
believe
pure tones
in the vehicle are going to be difficult, if not impossible to localize. Finally,
most vehicles exhibit a Shroeder Frequency (Fs) between 50 at 120 Hz; the Fs (or cabin-gain
frequency) is vehicle dependent, and is the frequency at which resonances become so tightly
packed in frequency and space that the room behaves quite uniformly.
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Acoustic treatment can be very effective above 200 Hz, depending mostly on the polar
radiation pattern of the speaker. In the case of the Legatia L3, a small cone midrange driver,
the polar radiation pattern is quite large at lower frequencies, with a narrowing of the
radiation pattern (“beaming”) at frequencies into the treble bandwidth. While it would be
convenient to only have to worry about the speaker itself, we also must be concerned with
crossover and baffle design as well (see Legatia L3 Mounting Baffle Requirements section).
Should the Legatia L3’s be placed in the kick panel locations, one may find that a notable
improvement can be made by adding acoustical treatments, such as open-cell foam, into the
underside of the dashboard. Likewise, should the L3’s be placed up high on a-pillars, or in the
dashboard, where comb filtering (reflective summation and cancellation off of a hard surface,
such as a windscreen) may become an issue, a dashboard “mat” or other soft furnishing may
be a noticeable improvement. It will require trial and error to get it right, but the learning is in
the experimentation!
Physical Installation of the L3’s
We hope that by now you feel more comfortable in the actual physical installation process.
Unfortunately, there are no rules in car audio, only several hypothesis and theorems that seem
to work for
most
vehicles. Your vehicle may be different, and defy everything we know, and
everything written in this manual. You may find that getting that rich, detailed sound that you
crave may require some experimentation and a lot of work to make it right. Or you might be
fortunate to have a vehicle that sounds excellent with minimal work. Have patience and work
through the issues; the result will be a rewarding musical experience in your car!
The L3’s can now be mounted in the location deemed to be the best for your vehicle, using
the tenets outlined in this manual. Connect the speaker’s large terminal to the amplifier’s
positive speaker output and the speaker’s small terminal to the amplifier’s negative speaker
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As an aside, one significant benefit of car audio sound systems is that frequencies below the lowest room resonance increase at a theoretical
12 dB/octave…it’s no wonder car audio systems have such great bass!
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