6
C Series C 20:8X, C 10:8X, C 10:4X and C 5:4X Operation Manual
4 WELCOME
4.1 Introduction
Thank you for choosing Lab.gruppen C Series power
amplifiers for your sound reinforcement system
installation. We are confident that you will be
very pleased with the performance, configuration
flexibility, reliability, and long-term durability offered
by the C Series products.
This manual provides a comprehensive guide to the
features and functionality specifically of C Series
model C 20:8X, C 10:8X, C 10:4X and C 5:4X ampli-
fiers. Please read through it in its entirely to become
fully acquainted with the many configuration options
and multiple layers of protection circuitry.
To facilitate timely installation and use of this C Series
product, we have included a Quick Guide Overview
(section 6). This brief summary, in conjunction with
Installation (section 5), contains the basic information
needed to safely install the amplifier and place it in
service. However, we highly recommend reading
through this manual in its entirety, beginning with
Main Features and Technologies and continuing
through Operation and Performance. As you become
thoroughly familiar with all aspects of operation, you
may learn of features or options that will affect your
choices on amplifier modes or loudspeaker system
configuration.
Lab.gruppen C Series power amplifiers are designed
and built specifically for the unique demands of
permanent installation applications. C Series
amplifiers offer the optimum combination of high-
quality audio reproduction, flexible features, ease of
installation, and ultimate reliability in normal use.
By packing four or eight channels of reconfigurable
power amplification into a 2U chassis, the C Series
achieves unprecedented power and channel density.
The benefits of compact dimensions include reduced
rack space requirements and minimal heat build-up.
The flexible output stages enable each amplifier chan-
nel to be set for either low impedance or constant
voltage (70 Vrms / 100 V peak) mode. NomadLink,
an easy-to-use network for monitoring and control,
is implemented as a standard feature on all C Series
amplifiers.
Although C Series features and facilities are tailored
to installation applications, at the heart of each
amplifier is the same advanced technology that has
made Lab.gruppen the benchmark of quality for touring
concert systems: exceptional sonic performance,
rugged construction, proven reliability, and protection
features that anticipate every unwelcome possi-
bility.
This manual is shipped with amplifiers
carrying the C…X designation (C 20:8X, C
10:8X, C 10:4X and C 5:4X). These four
models within the C Series are distinguished
by both four- and eight-channel versions, lower
power output, and several added features. Any refer-
ences to “C Series” in this manual also apply to the
other models in the Series. References that apply
only to the C…X models will specify “C…X ampli-
fiers”. An alternate operation manual is shipped with
model C 68:4, C 48:4, C 28:4 and C 16:4 amplifi-
ers.
4.2 Main features
Your new C Series amplifier incorporates a number
of sophisticated technologies – many of them pro-
prietary to Lab.gruppen – that are provided to ensure
the best possible performance and many years of
reliable operation. Familiarizing yourself with these
technologies will prove invaluable in setting up and
optimizing your loudspeaker system.
4.2.1 Class d output stage and universal
power supply with PfC
All C…X amplifiers employ a unique Class D output
stage that is ideally matched to the lower power
outputs of these amplifiers. The original C Series
amplifiers, with power output up to 6800 watts total,
require use of Lab.gruppen’s patented Class TD in
order to maintain sonic purity and high efficiency;
however, at the lower power levels of the C…X
models, Lab.gruppen’s advanced Class D circuit
offers the same performance benefits in a more
cost effective manner.
C…X amplifiers also incorporate a newly developed
universal switching power supply which accepts any
voltage from 100-240 V (+/- 10%) @ 50 or 60 Hz. A
Power Factor Correction circuit stabilizes current
draw under changing conditions.