QSC Audio Data Port Access Card DDI-3 On/Off Control, Inputs, Output Monitors, I. Introduction

Instructions for the DDI-3 DataPort Accessory Card

I. INTRODUCTION

The DDI-3 DataPort Accessory Card converts a QSC amplifier’s DataPort to an eight-position terminal block, providing convenient access to the pins of the amplifier’s DataPort; this is useful for connecting input signals or implementing a remote on/off (standby) system without using a DataPort cable. Four solder pads provide access to the amplifier’s output voltage and current monitors.

QSC ISA, CX, DCA, SRA, PowerLight, and PowerLight 2 Series amplifiers feature a DataPort for every two audio channels. Therefore, one- and two-channel models have one DataPort, while four-channel models have two and eight-channel models have four. On the four- and eight-channel CX and DCA models, only the DataPort for channels 1 and 2 has the power supply standby feature. ISA models do not have power supply standby or output voltage and current monitoring.

VMN1	STBY
	CGND
IMN1	CH2+
	CH2-
IMN2	AGND
VMN2	CH1+
	CH1-
	AGND

Figure 1. The DDI-3

Run

ON/OFF CONTROL

A TTL-type logic low at DataPort pin 2, such as a short to ground (Figure 2), puts the power supply in standby. Opening the short will restart the power supply, with no inrush current surge. The DDI-3 now has an isolation diode to allow the control of multiple amplifiers with a single switch (Figure 3).

INPUTS

Through its DataPort, an amplifier’s input sensitivity (the input voltage required to reach full rated output power) is approximately 3 volts RMS, at full gain and with an 8Ω load on each channel. Use the + and - terminals for balanced connections; the AGND terminal is audio ground, for conecting a cable shield when necessary. For unbalanced connections, connect the signal conductor to the + terminal and the cable shield to both the AGND and - terminals.

Standby

VMN1	STBY
	CGND
IMN1	CH2+
	CH2-
IMN2	AGND

CH1+

VMN2

CH1-

AGND

Figure 2. On/off control of a single amplifier

OUTPUT MONITORS

There is a VMON and an IMON output for each amplifier channel. The VMON output is a sample of the amplifier channel’s output voltage, scaled so that full output into an 8Ω load equals approximately 3 volts RMS. The IMON output is a voltage proportional to and in phase with the amplifier channel’s output current; the scaling varies among the various amplifier models; contact QSC for details if you wish to use this feature.

USAGE WITH DCM, CM16A, BASIS, AND QSControl.net

To maintain power on/off functionality when using a DDI-3 on the DataPort of a DCM, CM16a, Basis, or QSControl.net product, solder a wire jumper across the diode located on the same side of the circuit board that the HD15 connector is mounted. This does not apply to DDI-3 interfaces mounted on amplifiers or on amplifier- mounted accessories.

II. INSTALLATION

VMN1

IMN1

IMN2

VMN2

VMN1

IMN1

IMN2

VMN2

VMN1

IMN1

IMN2

VMN2

STBY CGND CH2+ CH2-

AGND CH1+ CH1-

AGND

STBY CGND CH2+ CH2-

AGND CH1+ CH1-

AGND

STBY CGND CH2+ CH2-

AGND CH1+ CH1-

AGND

Run

Standby

The DDI-3 kit (QSC part # SG-000235-00) includes these items:

DDI-3 board

Two #4-40 × ¼” black screws

Installation guide

Use this procedure to install the DDI-3:

1.Turn off the amplifier.

Figure 3. On/off control of several amplfiers with a single switch

2.If you are using the output voltage or current monitoring features, solder the wires to the appropriate pads on the DDI-3 before attaching it to the amplifier.

3.Plug the DDI-3 into the amplifier’s DataPort. Use the two screws included to secure it; do not overtighten them.

2