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The cross-over unit
A very sophisticated, low-loss passive FSR cross-over
unit (FSR = Fast Signal Resp onse) adjusts the combina-
tion of electrostatic unit and valve output stage
(TCI 1 RE), and of electros tatic unit and repeater
(TCI 2 E), to match the output of the other sub-system s
in the loudspeaker.
The circuit boards of these cross-over units feature a
large-area copper layer on the top surface whose sole
purpose is to act as the earth conductor.
The copper tracks on the underside connect the compo-
nents with each other. This layout ensures that the criti-
cal earth re ference potential is not falsified by the large
signal currents which flow. The usua l voltage losses
caused by na rrow conductor tracks do not occur in this
design, which means that much higher currents can
safely be used. Undesi red effe cts on sign als s uch a s
inter-modulation or cross-talk between the individual
tracks are also minimised.
The components of the cross-over unit are extremely
low-resistance types, an d are designed to minimise los-
ses.
The large capaci tance required is implemented in the
form of several small capacitors wired in parallel, as this
arrangement red uces series inductivity and resistance,
and also improves slew rates. All these design feature s
are aimed at obtaining maximum possible signal fidelity.
To reduce the distortion which can arise with large cur-
rents, virtually all the coils are of the air-core type.
High-quality cable is employed fo r all internal wiring
inside the cabinets.