Telex Integrated Signal Processor ISP-100 - Manual (Page 91)

8-21
Processing Components - Crossover
depending upon whether 12 dB/octave or 24 dB/octave filters are
used, respectively.
The following sections will show this sum-to-allpass trait to hold true
for the ISP-100 Linkwitz-Riley 3-way and 4-way crossover
implementations.
Three-way
From Figure 8-6
Summed Response = LP
1
LP
2
± HP
1
LP
2
±
θ
1
HP
2
= (LP
1
± HP
1
)LP
2
±
θ
1
HP
2
=
θ
1
LP
2
±
θ
1
HP
2
=
θ
1
(LP
2
± HP
2
)
=
θ
1
θ
2
Q.E.D.
There is an alternate configuration, not implemented in the ISP-
100, that also has this property:
Summed Response = LP
1
θ
2
± HP
1
LP
2
± HP
1
HP
2
= LP
1
θ
2
± HP
1
(LP
2
± HP
2
)
= LP
1
θ
2
± HP
1
θ
2
= (LP
1
± HP
1
)
θ
2
=
θ
1
θ
2
Q.E.D.
Four-way
From Figure 8-9
Summed Response = LP
1
LP
2
θ
3
± HP
1
LP
2
θ
3
±
θ
1
HP
2
LP
3
±
θ
1
HP
2
HP
3
= (LP
1
± HP
1
)LP
2
θ
3
±
θ
1
HP
2
(LP
3
± HP
3
)
=
θ
1
LP
2
θ
3
±
θ
1
HP
2
θ
3
=
θ
1
(LP
2
± HP
2
)
θ
3
=
θ
1
θ
2
θ
3
Q.E.D.
Low, Low-Mid, Mid, Mid-High and High Controls
The Low, Low-Mid, Mid, Mid-High and High buttons determine if
that section of the crossover is bypassed. If the word Low, Low-Mid,
Mid, Mid-High or High is displayed on the button, then that portion of
the crossover is not bypassed. If the word Bypassed is displayed on
the button’s face, then that portion of the crossover is bypassed.
Clicking on the buttons will toggle their settings.
Link/Unlink Control
The Link/Unlink button determines if the settings in the crossover
track their corresponding partners. A simple rule of thumb is that
when the sections are linked, the component on the right will track its
partner on the left. Clicking on the button(s) will toggle the settings.
Slope
To change settings, click on the arrow next to the number in the text
box. A selection list will appear. The list may or may not be
scrollable. To make a selection click on the desired entry.