QSC Audio MX 1000a PARALLEL, STEREO, or Bridged Operation, Instructions for Bridged Operation

PARALLEL, STEREO, OR BRIDGED OPERATION

The Parallel-Stereo-Bridge switch is located on the input panel, next to the input jack for channel 1).

The most commonly used operating mode for a power amplifier is “Stereo,” in which the two channels are independent and separate all the way from input to output. Set the switch in the center position for stereo operation.

“Parallel” ties the two channel inputs together so that both will be driven by the same signal, without the need for external jumpers or wiring. After the inputs both channels operate independently; though they carry the same sig- nal, their gain controls affect only their respective chan- nels, and they must use separate speakers. Never par- allel the speaker outputs!

The “Bridge” position uses both channels to provide about three times the power to a single speaker load that a single channel does. In this position the switch feeds channel 2 with an inverted signal from channel 1. Thus, when one channel “pushes,” the other “pulls,” providing twice the voltage swing of a single channel.

BRIDGED-MONO MODE CAUTION:

The voltage across the output terminals of a bridged MXa amplifier may equal or exceed 100 volts rms and may be as high as 170 volts (MX 3000a), 130 volts (MX 2000a), or 120 volts (MX 1500a). Use fully insulated CLASS ONE wiring, and the load must be rated for up to 2400 watts (@ 8 ohms) for the MX 3000a, 1300 watts (@ 8 ohms) for the MX 2000a, 1000 watts (@ 8 ohms) for the MX 1500a, and 700 watts (@ 8 ohms) for the MX 1000a.

VORSICHT BEIM ÜBERBRÜCKTEN

MONO-MODUS:

INSTRUCTIONS FOR BRIDGED

OPERATION

1.Set the switch to the “Bridge” position.

2.Connect the signal to channel 1’s input only. Do not connect anything to the input of channel 2.

3.Turn up the gain on channel 2 all the way. Use channel 1’s gain control to set the level. Both channels’ “SIG” and “CLIP” indicators should flash identically. (If you have used other amplifiers, this step may be different. But it is correct; in the bridged mode, chan- nel 2 receives its feed from a sample of channel 1’s output. The sample is calibrated such that channel 2, at full gain, will produce a voltage equal in magnitude but opposite in polarity to channel 1’s.

4.Connect the single speaker load across the red binding posts of the amplifier outputs as shown in Figure 2-2. The positive speaker wire goes to channel 1, and the negative to channel 2.

TIP NEG RING POS

SLEEVE GND

STEREO

CH 1 PARALLEL BRIDGE

Figure 6: Parallel-Stereo-Bridge switch shown in the normal (Stereo) mode position.

Switch on Input Panel	STEREO
(Left side of rear panel)

Zwischen den überbrückten Terminals eines MXa- Verstärkers besteht eine Ausgangsspannung mit einem quadratischen Mittelwert von mehr als 100 Volt und vielleicht von bis zu 170 Volt (MX 3000a), 130 Volt (MX 2000a), oder 120 Volt (MX1500a). Zu verwenden ist voll isolierte Verdrahtung der US-Klasse Eins, und die angeschlossene Belastung muß für bis zu 2400 Watt (8 Ohm) beim MX 3000a, 1300 Watt (8 Ohm) beim MX 2000a,

– BRIDGED MONO –

+	+
CHANNEL 2	CHANNEL 1

– –

STEREO 4 OHM MIN/CH. CLASS 2 WIRING

BRIDGED MONO 8 OHM MIN. CLASS 1 WIRING MUST BE USED BRIDGED MONO OPERATION: PLACE BRIDGING SWITCH ON INPUT PANEL

TO BRIDGED POSITION. CONNECT INPUT SIGNAL TO CH 1 ONLY. CONNECT SPKR (+) TO CH 1 (+) OUTPUT. CONNECT SPEAKER (–) TO CH 2 (+) OUTPUT. SET CH 2 GAIN FULLY CLOCKWISE AND REGULATE LEVEL WITH CH 1 GAIN CONTROL.

PARALLEL BRIDGE

–

+

1000 Watt (8 Ohm) beim MX 1500a, und 700 Watt (8 Ohm) beim MX 1000a ausgelegt sein.

CONNECT ONE SPEAKER LOAD ONLY.

Figure 7: For Bridge mode, use CH 1 input only, and set Input switch and connect load as shown.

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