Hybrid Audio Technologies Clarus-Series, Installation Manual

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Clarus User’s Manual ©Hybrid Audio Technologies Page 23 of 26
increasingly important as frequencies range into the Clarus midbass’ upper bandwidth, where the
power response is more uniform and incident and reflected waves are indistinguishable. In practical
terms, keep baffle dimensions small with respect to the size of the Clarus midbass, chamfer or round
sharp edges (including, in particular, the mounting hole’s rear inner edge), flush-mount the speaker
whenever possible, and use shallow, surface-mounted hardware. Also, remove all unnecessary
protrusions from the baffle surface.
Acoustic Treatment
A considerable benefit can be made to any mobile audio system with the select placement of acoustic
treatments. The purpose of using acoustic treatments is to reduce the amount of reflected energy in
the hostile automotive environment, and hear more of the direct sound being emanated from the
speaker. It is akin to the signal to noise (S/N) ratio in a piece of electronics, where the signal could be
considered the direct energy coming from the speaker, and the noise could be considered the
reflected waves off of nearby surfaces, such as windows, hard center consoles and door panels,
windscreens, and etc. A word of warning though: there is a fine line between too little and too much
acoustic treatment; just as some vehicles can benefit from some selectively applied treatments, there
is a point where the vehicle can begin to approach “semi-anechoic” conditions, and lose its liveliness,
which is not ideal. 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 Schroeder Frequency (Fs)
between 50 at 125 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 acoustical properties of
the vehicle behave quite uniformly. (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!)
Acoustic treatment can be very effective above 200 Hz, depending mostly on the polar radiation
pattern of the speaker. In the case of the Clarus midbass, the polar radiation pattern is quite large at
lower frequencies, with a narrowing of the radiation pattern (“beaming”) at frequencies into the treble
bandwidth.
Should the Clarus midbass 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 midbass, or in fact the C1 tweeter 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!