16
C Series
Quick Start Guide
17
NomadLink / Ethernet network setup
The amplifier includes, as a standard feature, internal facilities for the NomadLink monitoring and control network. All features of the NomadLink network are
accessible via a PC running Lab Gruppen’s proprietary DeviceControl software. A single rackspace NLB 60E NomadLink Bridge & Network Controller accepts the TCP/IP
data stream from the computer and converts it to the NomadLink protocols. Even when no computer is connected, the NLB 60E can initiate stand-alone power on/off
and muting functions, as well as report any fault or warning conditions.
The PC is connected to the NLB 60E using a standard Ethernet interface and a crossed Cat-5 cable (peer-to-peer setup). If a hub or switch is in the network, standard
“straight” Cat-5 cables must be used. The front and rear Ethernet connections on the NLB 60E can be used individually, but only one PC at a time running DeviceControl
can access the subnet.
NOTE:
Many newer laptop computers will allow peer-to-peer connection with the NLB 60E using a standard “straight” Cat-5 cable instead of a crossed cable.
The default fixed TCP/IP address of the NLB 60E is 192.168.1.166. The subnet mask is 255.255.255.0. For further system configuration details, please refer to instructions
supplied with the NLB 60E unit.
The NomadLink connections between amplifiers use standard “straight” Cat-5/RJ45 equipped cables.
NOTE:
US National Differences cl.16.3 requires that NomadLink network cables must be rated VW-1.
The OUT port from the NLB 60E must be connected to the IN port of the first amplifier. The OUT port from the first amplifier in turn connects to the next amplifier’s IN
port to form a daisy-chain The OUT port on the last amplifier is connected to the IN port on the NLB 60E to close the loop.
NOTE:
There are performance limitations to cable lengths on a NomadLink network, both in terms of total cable length in the loop and between any two devices.
These limitations follow standard Ethernet cabling protocols. Read the Operation and Performance chapter in this manual, or the Operation Manual supplied with the
NLB 60E, to ensure the network is configured within these constraints.
TIP:
Although the network will function as an open loop under most circumstances, it is strongly recommended that the loop be closed by connecting the last
amplifier’s OUT port to the NLB 60E’s IN port. Doing so will improve redundancy and communication speed.
External contact closures and 24 V low/high triggers can be connected to the GPI connectors on the NLB 60E for control of fire-alarm systems or external power
sequencers. For more details read the instructions supplied with the NLB 60E.
(1)
(1)
(2)
(2)
Crossed RJ45 Ethernet cable between
NLB 60E and PC. If bridge is connected
to switch of HUB, use "straight" cable.
PC can also be connected on front panel.
"Straight" RJ45 cables between
bridge and amplifiers
ETHERNET
ETHERNET
GENERAL
PURPOSE
INPUT, GPI
NOMADLINK
IN
OUT
NOMADLINK
IN OUT
NOMADLINK
IN OUT
Operation and performance
Introduction
The following sections provide comprehensive information on amplifier connection, setup, operation, and performance. The detailed information included here is
essential to realizing the full functionality of the C Series amplifiers.
Operation precautions
• Make sure that the Power switch and the Remote switch on the amplifier front-panel are set to “off” before making any input, output or network connections,
and also before manipulating the DIP-switches on the rear-panel.
• Make sure that the AC mains voltage is correct and matches the voltage printed on the rear-panel of the amplifier (115 V or 230 V).
• Make sure that no signal is present at the input to the amplifier when powering up. This could produce an unintentionally loud initial volume from the speakers.
Signal flow and headroom
Signal flow blocks
All C Series amplifiers have the same signal flow and feature set. The only difference is the amplifier’s maximum output current per channel.
The input stage of all C Series amplifiers has a high sensitivity to provide ample system headroom. This in effect means that the input stage is almost impossible to clip.
Overall amplifier input gain is adjusted using the input stage DIP-switches. Please note that the gain setting is global, affecting all four channels. Following the input
stage, the dedicated level control on each channel allows signal attenuation from 0 dB to minus infinity.
The CPL (Current Peak Limiter) section dynamically limits the input signal based on three parameters: sensed current level, feedback from the output stage, and
sensed voltage clip from the VPL (and output amplifier voltage clip if “Soft Clip” activated). This ensures that power output is maintained within the design limits of
the amplifier.
The adjustable VPL (Voltage Peak Limiter) sets the maximum output voltage and therefore also the maximum output power. Eight (8) different voltage stages are
available using the DIP-switches on the rear-panel. See table in Appendix section with VPL ratings at typical loads.
The sophisticated output section monitors faults and generates appropriate warnings, which are displayed on the amplifier front-panel and transmitted through the
NomadLink network. These alerts allow the operator to adjust system settings and thereby avoid problems. In the rare event that conditions are extraordinarily severe,
the amplifier will shut down until the fault or problem setting has been rectified or adjusted. These sensing circuits are also employed to feed back voltage and current
level information, via a side chain, to the limiters. Sensing circuits also transmit local amplifier module temperature and power supply temperature to the appropriate
protection mechanisms. Read the Protection, Faults and Warnings section for further details.
Headroom, sensitivity and VPL / Gain settings
The input amplifier and limiter system is designed to accommodate extremes of performance. Typically, exceeding maximum input by much as +10 dB will only result
in a 1% increase in distortion. The following schematics illustrate how the adjusable VPL and Gain circuitry affect input sensitivity and output power:
The tables to the left of the drawing below show input sensitivity for a C 68:4 with an 8 ohm load and 141 V peak (max.) and 42 V peak (min.) respectively for the
eight different gain stages b23 dB and +44 dB. The resulting output power is displayed in dBu, Vrms and Watts in the tables to the far right. Complete input
sensitivity tables for all VPL and Gain settings for as applicable to C Series models can be found at www.labgruppen.com.
The headroom available through the input stage to the clip limiter is shown by the dotted lines as +10 dB at 141 V peak and +20.4 dB at 42 V peak. These lines
illustrate the additional signal level that can be accepted at the input before any significant distortion will appear at the input stage.
NOTE:
If you use the level potentiometer in the signal chain to reduce the level by an amount greater than the headroom relative to input sensitivity, AND you drive the
amplifier to clip level, you are in danger of clipping the input stage before the current or voltage peak limiters are activated.