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SYSTEM PLANNING
The largest possible impact on any audio
system (home or car) is the quality of
loudspeakers used and their placement.
EFFICIENCY defines how loud a speaker
will play for a given input power and is
often quoted at 1 watt input and measured
at a 1 meter distance. When designing a
system you want to keep the component
efficiencies as close as possible. Always
match components for efficiency and
complementing frequency response to
ensure smooth transition from low
trequencles to hrgher ones for accurate
performance. Remember that for every 3
the amplifier has doubled it's power output.
SPEAKER CONFIGURATIONS can become a problem in autosound installations. We would
front and partly behind us. This virtually dictates good midrange and tweeter
in front, usually mounted in the doors for good left/right balance, with high-pass
crossovers set greater than 80-100 Hz. For deep bass a subwoofer is required but is nearly
always located behind us in a rear trunk or hatch area. If the subwoofer crossover is too
high in frequency male voices can be heard "gurgling" out of the subwoofer speaker and
therefore pulls the sound-stage to the rear of the car, which is undesirable.
AMPLIFIER POWER is important but should be of lesser importance compared to speaker
choice and placement. Matching the rms (continuous) power levels to that of the speaker
is important but it should be noted that under-powering a system can often cause more
damage than slightly overpowering it. If the speakers are rated for 50 watts rms, you can
often drive them with a 100 watt power amp without concern. IMPEDANCE is the electrical
resistance to AC current flow and is typically 4 ohms for most car speakers. Impedance
loads for a speaker configuration shouldn't fall below 2-4 ohms for most installations to
avoid amplifier overheating, regardless of manufacturer (Impedance = D.C. resistance of
the voice coil wire + A.C. resistance due to the coil of wire formed).
Voice
The Dual
Coil woofer is actually quite old in the home audio industry but still
relatively new to the car audio world.
flexibility in installation. In order to raise the sound pressure level (loudness) in a car, you
can either add more speakers or add more amplifier power to drive a single speaker.
cars cannot fit two subwoofers and their necessary enclosure volumes but can easily fit
larger power amplifiers and a single woofer. Simply speaking, the DVC woofer allows you
to make up for speaker deficiencies with additional amplifier power.
There are basically four types of DVC installation: the ECONOMY MODE simply ties the
two voice coils together to yield more SPL; the LIMITED SPACE MODE uses higher
amplifier power to offset the need for a separate subwoofer and its enclosure; the
channel amp in a "Tri-Mode" configuration; the HI-SPL MODE increases the perceived
Pressure Level in the car's bass by loading down the output impedance of the
amplifiers thus'achieving higher output power from the amplifiers. For any speaker loading
mode, care must be taken to avoid loading the amplifier's output below it minimum
impedance value (e.g., 2 ohms).
The largest advantage of the DVC woofer is in the
FREQUENCY &I '. "
Many
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