Alpine SPX-Z18T - Manuel (Page 12)

10
Jumper Group Function
Although recommendations are made for the most common system types in the following
pages, there are actually over 1000 unique and useful jumper combinations available for a
wide variety of vehicles, installations and personal tastes. While this flexibility has obvious
advantages, too many choices can also be confusing. Therefore, it will be helpful to under-
stand the function of each jumper group in order to tune the network more effectively:
TW-HP:
In addition to functioning as a high-pass filter, this section also provides the necessary
adjustments for proper integration with the midrange. The transition between these two
drivers in the frequency and time domains is essential to the total performance of a
multi-element system, as it has a direct effect upon imaging, staging, focus
and tonal balance. In real world installations, distance and angle of both drivers relative
to the listener, their proximity to each other, and certainly the vehicle's interior also exert
additional influence. In anticipation of this, variations of filter slope, Q, cut-off frequency
and resultant phase shift are provided so that "phase linkage" and flat summation can
be maintained. As a general reference, the layout and available filter types of the tweeter
high-pass section are provided below:
TW LEVEL:
In general, this section provides precise level adjustment for optimum performance or
personal taste. However, it also allows for “tilting” of the filter frequency response in
order to compensate for the natural high frequency roll-off associated with off-axis lis-
tening angles. In other words, this jumper choice will have a direct effect on both Q and
cut-off frequency of the various filter combinations listed above. This effect can be seen
in the filter transfer function graphs for the various system types. If the TW-HP section is
set to bypass in favor of an electronic crossover, the off-axis feature will no longer func-
tion, but basic level adjustment will still be possible.
R1 = 1.5
Ω
R2 = 3.3
Ω
R3 = 4.7
Ω
R4 = 5.6
Ω
R5 = 0.5
Ω
C1 = 3.3
µF
C2 = 8.2
µF
L1 = 0.65mH
L2 = 0.1mH
HP-1 HP-2
BYPASS
+1.5dB/15 °
0dB/0 °
–1.5dB
–3dB
L1 L2
R4
R1
R2
R3
C1
C2
R5
+4dB/30 °
HP-3
+
+
–
–
1 st Order:
• No HP jumpers
• HP3
2 nd Order:
• HP1 + HP2 + HP3
• HP1 + HP3
• HP2 + HP3
3 rd Order:
• HP1
• HP2
• HP1 + HP2