Common analogue grounding issues. AWG DUAL USB POWER CHARGER FOR NDS LITE

AXYS ® Intellivox 808/1608 Installation Manual Rev 1.1

CoMMoN ANAloGUE GroUNDING ISSUES

Correctly connecting the IntelliAmp to ground has several benefits:

1. Safety. The GND terminal of the Neutric PowerCon ® connector provides a direct low impedance path from the metal parts of the chassis to ground. Always connect this terminal.

2. reduction of rF emission. Although the IntelliAmp electronics are well shielded and external connections are decoupled to prevent RF emission from the internal high speed digital circuits, this protection will not work properly if the chassis is not connected to ground.

3. rF Immunity. RF currents induced in the signal cables by external RF fields are effectively shorted to chassisground, provided that the cable screen (shield) is of sufficiently low impedance.

In addition to the mains ground, the IntelliAmp rear panel connectors have ground pins marked in 3 different ways.

Each serves a dedicated purpose and care should be taken that they are not interchanged or connected to each other.

• Pins marked GND are connected internally directly to the chassis of the IntelliAmp. There are GND pins on the audio line input connector and the ambient SPL mic/temperature sensor connector. These GND pins are for connecting the screen (shield) of the audio and sensor cables.

• Two pins marked AGND are fitted to the ambient SPL mic and temperature sensor connector, and serve as a signal reference only. AGND should not be connected to any other ground pin (GND or DGND) on the chassis.

• The RS-485 connector has one pin marked DGND and is intended as a terminal for the network cable screen

(shield). Since the RS-485 interface is optically isolated

(to prevent ground loops), DGND has no relation to the chassis ground. DGND should not be connected to any other ground pin (GND or AGND) on the chassis.

SoFTWArE AND FIrMWArE UPDATES

The AXYS ® WinControl application is freely available and can be downloaded from the download area of our website; http://www.jblpro.com. We advise installers, users and engineers to check our site regularly for updates.

Intellivox firmware and DSP software upgrades will also be made available through the website.

For further information about how to use WinControl please refer to the WinControl Help files.

NETWorK CABlES

The type of cable necessary for correct operation of the RS-

485 network is twin twisted pair with each pair individually shielded. Numerous cables of this type are readily available and cables broadly meeting the specifications of the example cable given below are likely to be suitable.

Example of a preferred cable type:

PARAMETER VALUE

Type

Characteristic impedance

Capacitance (core to core)

Capacitance (core to screen)

DC resistance (core)

DC resistance (screen)

BELDEN ‘Datalene’ series

No. 9729 2-pair

100 ohms

41 pF/m

72.5 pF/m

78.7 ohms/km

59.1 ohms/km

201112/IvxHPIM_v1.1

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