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QTA-

1120P/1240P

 

User Manual

User Manual

Q-Tech Commercial Series

QTA-1120P/1240P

4

Power Source

AC Power Source

The supply transformer has been designed for 
AC 240V /115V (±10%) 50 /60 Hz.

DC Power Source

Battery Connection (24Vdc)

When using external batteries, please ensure 
the amplifier is grounded via the screw 
terminal. (Electrical stability of the system 
will be improved by providing a good earth 
ground.) When connecting batteries, please 
ensure correct polarity.

Main Connections

Each input has XLR and Phone jack input.  
Use the one you want

Pin Assignments:

Balanced Audio (3 pole XLR):
Pin 1: 

Ground / Screen

Pin 2:

In phase / +ve / Hot

Pin 3:

Out of phase / -ve / Cold

Unbalanced Audio (3 pole XLR):
Pin 1:

Ground / Screen

Pin 2:

Signal

Pin 3:

Ground / Screen (connect to pin 1)

Speaker Output Connection

The speaker output screw terminal is on the 
rear panel.  It can connect low impedance 8 
ohm, or high-level 70V or 100V speaker.  Use 
only one of these output connections for 
corresponding speaker.

As a guide for the correct gauge of wire, we 
recommend the following:

For best performance when using long lines 
between microphones/mixer and or amplifier 
use balanced lines. These have the effect of 
cancelling out any noise or hum that may be 
induced into the cables. the amplifier to be 
processed externally and then returned to the 
power amplifier section of the amplifier. The 
connecting link must be plugged in for normal 
operation as a mixer/amplifier. “PRE OUT” is 
after the tone controls and the master volume

100V

Up to 50m

AWG25-26 (0.15mm2)

50m - 200m

AWG20 (0.5mm2)

Over 200m

 AWG18 (0.75mm2)

70V

Up to 50m

AWG24 (0.20mm2)

 50m - 200m

 AWG17 (1.0mm2)

Over 200m

AWG16 (1.5mm2)

Low 

Impedance 

(4

Ω)

Up to 10m

AWG18 (0.75mm2)

10m - 30m

AWG13 (2.50mm2)

Sensitivity Selection Switch

Place the switch on 100mV or 1V position for 
corresponding sensitivity of signal source 
from other devices.

Booster Output Connection

Use XRL (female) or phone jack to connect 
booster output to another amplifier.

Parallel / Mono Switch

The amplifier includes both male and female 3 
pin XLR connectors, labeled input and output. 
While the female is normally used as the input 
to the amplifier, both XLR’s are connected 
in parallel so either will work. When signal 
is connected to one XLR, the other XLR 
becomes a line level output allowing the 
input signal to be distributed (split) to other 
amplifiers. In some projects, the same input 
may be looped through to multiple amplifiers 
using this method. Up to 6 amplifiers can be 
looped together without any noticeable loss 
in level. A distribution amplifier should be 
used when more than 6 amplifiers need to be 
looped.

1

3

2

Plug

1

3

Socket

2

Viewed from Solder

Side of Plug/Soceket

Summary of Contents for Q-Tech QTA1120P

Page 1: ...Q Tech Commercial Series QTA1120P 1240P Power Amplifiers User Manual PUBLIC ADDRESS AMPLIFIER QTA 1240P OUTPUT LEVEL 8 Pwr 10 8 3 0 3 POWER ...

Page 2: ...run in conduit together with power cables ENSURE that all loudspeakers are in phase ENSURE that there are no short circuits on the loudspeaker line before connecting to the amplifier It is also advisable to check the final impedance to the amplifier with a dedicated impedance meter to determine power draw is within the amplifiers limits IMPORTANT The wires in the mains lead are coloured In accorda...

Page 3: ... Manual Q Tech Commercial Series QTA 1120P 1240P 1 Contents Introduction 2 Description 2 Front Panel Layout 3 Rear Panel Layout 3 Power Source 4 Installation Practice 5 Operation 5 Trouble Shooting 6 Specifications 6 Technical Notes 7 ...

Page 4: ...n to detail your amplifier will deliver its best results Please red the section Constant Voltage Distributed Speaker Systems Demystified Unpacking Please inspect the amplifier carefully immediately after unpacking If you find any damage notify your supplier dealer immediately Only the shipper may file a damage claim with the carrier for damage incurred during shipping Description QTA series of Pow...

Page 5: ... Supply Terminal 12 MIC 4 Aux 1 Selector Switch 6 Speaker Output Terminal 13 Phone Jack Input 7 Phone Jack Output Front Panel Layout PUBLIC ADDRESS AMPLIFIER QTA 1120P OUTPUT LEVEL 8 Pwr 10 8 3 0 3 POWER 1 2 3 VOLTAGE SELECT AC 115 240V 50 60Hz FUSE 250V T5A 24V DC COM 8Ω 70V 100V CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN CAUTION TO PREVENT ELECTRIC SHOCK DO NOT REMOVE COVER OR BACK NO USER SERVI...

Page 6: ...nto the cables the amplifier to be processed externally and then returned to the power amplifier section of the amplifier The connecting link must be plugged in for normal operation as a mixer amplifier PRE OUT is after the tone controls and the master volume 100V Up to 50m AWG25 26 0 15mm2 50m 200m AWG20 0 5mm2 Over 200m AWG18 0 75mm2 70V Up to 50m AWG24 0 20mm2 50m 200m AWG17 1 0mm2 Over 200m AW...

Page 7: ...nother amplifier When it is connected to another amplifier put the switch on Parallel position to maintain maximum gain Installation Practice Step 1 Take a piece of figure 8 cable connect the stripe coloured wire to the 100V terminal and the uncoloured wire to the COM on the amplifier terminal strip Step 2 Connect the other end of the wire uncoloured to the Com EARTH connection on the ceiling spea...

Page 8: ...ually Blows Fuses Make sure that the speaker line is not shorted Check speaker types ratings and if on correct output Amplifier Keeps on Cutting In Out Make sure that there is adequate ventilation around the amplifier Check the vent slots on the front are not covered or blocked and the fan on the rear is functioning correctly Check also speaker types ratings and for any short circuits on the speak...

Page 9: ... speaker system How to calculate the correct number of speakers and what wattage connection for a given amplifier power If you connect too many speakers to an amplifier you will have distortion overheating of the amplifier and generally poor performance The problem is not really too many speakers it is more a problem of too much wattage draw exceeding the output capability of an amplifier A simila...

Page 10: ...ula See below Determining power by calculating total impedance The alternative to counting the speaker taping watts is to calculate the total impedance of the line which will also indicate the wattage necessary to drive the system correctly The computational formula is voltage squared divided by impedance Power Voltage2 Impedance When the speaker line reaches its top voltage of 70 Volts the formul...

Page 11: ......

Page 12: ...www questaudio net Quest Engineering Pty Ltd 86 Derby St Pascoe Vale VIC 3055 Ph 613 9354 9133 Fax 613 9354 9233 ...

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