Alpine i902D Owner'S Manual Download

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-EN

About the Crossover

Crossover (X-OVER):

This unit is equipped with an active crossover. The crossover limits the
frequencies delivered to the outputs. Each channel is controlled
independently. Thus, each speaker pair can be driven by the frequencies
for which they have been optimally designed.
The crossover adjusts the HPF (high pass filter) or LPF (low pass filter)
of each band, and also the slope (how fast the filter rolls off the highs or
lows).
Adjustments should be made according to the reproduction
characteristics of the speakers. Depending on the speakers, a passive
network may not be necessary. If you are unsure about this point, please
consult your authorized Alpine dealer.

• HPF (high pass filter): Cuts the lower frequencies and allows the higher

frequencies to pass.

• LPF (low pass filter): Cuts the higher frequencies and allows the lower

frequencies to pass.

• Slope: The level change (in dB) for a frequency change of one octave.
• The higher the slope value, the steeper the slope becomes.
• Adjust the slope to FLAT to bypass the HP or LP filters.
• Do not use a tweeter without the HPF on or set to a low frequency, as it

may cause damage to the speaker due to the low frequency content.

• Adjustment should be made according to the recommended crossover

frequency of the connected speakers. Determine the recommended
crossover frequency of the speakers. Adjusting to a frequency range
outside that recommended may cause damage to the speakers.
For the recommended crossover frequencies of Alpine speakers, refer to
the respective Owner’s Manual.
We are not responsible for damage or malfunction of speakers caused by
using the crossover outside the recommended value.

About Time Correction

The distance between the listener and the speakers in a car vary widely
due to the complex speaker placement. This difference in the distances
from the speakers to the listener creates a shift in the sounds image and
frequency characteristics. This is caused by the time delay between the
sound reaching the listener’s right versus the left ear.
To correct this, this unit is able to delay the audio signal to the speakers
closest to the listener. This effectively creates a perception of increased
distance for those speakers. The listener can be placed at an equal
distance between the left and right speakers for optimum staging.
The adjustment will be made for each speaker in 3.4 cm steps.

Adjust the time correction level of the front left speaker to a high value
and the rear right to zero or a low value.

The sound is not balanced because the distance between the listening
position and the various speakers is different.
The difference in distance between the front left speaker and the rear right
speaker is 1.75 m (68-7/8").
Here we calculate the time correction value for the front left speaker in the
diagram on the above.

Conditions:
Farthest Speaker – listening position : 2.25 m (88-9/16")
Front left speaker – listening position : 0.5 m (19-11/16")
Calculation: L = 2.25 m – 0.5 m = 1.75 m (68-7/8")
Time correction = 1.75 ÷ 343* × 1,000 = 5.1 (ms)

Speed of sound: 343 m/s (765 mph) at 20°C

In other words, giving the front left speaker a time correction value of 5.1
ms makes it seem as if its distance from the listener is the same as the
distance to the farthest speaker.

Time correction eliminates the differences in the time required for the
sound to reach the listening position.
The time of the front left speaker is corrected by 5.1 ms so that its sound
reaches the listening position at the same time as the sound of other
speakers.

Cut-off frequency
(1/3 octave steps)

Slope

Level

HPF

LPF

HPF

LPF

Subwoofer
(LPF)

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20 Hz -
200 Hz

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0, 6, 12, 18,