Eclipse - Fujitsu Ten CD8445 Stereo Receiver User Manual


 
119
How to operate the Sound Adjustment Mode
IX
Crossover
The frequency band that is stored by audio media such as CDs is a
fairly wide range from 20 Hz to 20 kHz, and it is difficult for a single
speaker to be able to play back all frequencies in such a wide range.
Because of this, several speakers can be used, with different
frequency bands (such as treble, medium and bass) allotted to each
speaker so that wide frequency ranges can be played back.
The "Crossover" function is used to allot the frequency ranges that
are to be played back by each speaker in accordance with the
installed speaker units and the layout of the speakers, in order to
obtain the maximum level of performance from the speakers and to
provide the most stable frequency characteristics.
The crossover function includes a high-pass filter (HPF) for playing
back treble sounds, and a low-pass filter (LPF) for playing back
bass sounds. In addition, the HPF and LPF are used in combination
in order to play back sounds in the medium range.
For example, when adjusting the HPF, frequencies that are lower
than the specified frequency are progressively dampened, rather
than simply not being played back at all. The "slope" adjustment
function is the function that is used to adjust these dampening
characteristics.
The slope characteristics of a filter are such that with larger slope
values (for example 12 dB/oct), the slope becomes steeper, and so
the amount of sound mixing in with neighboring bands becomes
less so that only the target band is played back. However, it also
causes the merging of sound between speakers to become poorer
and can result in greater distortion.
The crossover function is a filter that allocates specified frequency
bands.
A high-pass filter (HPF) is a filter that cuts out frequencies that are
lower than the specified frequency (bass range) and allows higher
frequencies (treble range) to pass through.
fc1(LPF) fc2(HPF) fc3(LPF) fc4(HPF)
20kHz
-3dB
Bass range Mid range Treble range
20Hz
fc*: Cutoff frequency
CD8445.book 119 ページ 2004年12月13日 月曜日 午前11時30分