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1
Redback® Q 2004
Impedance Meter
2.0 INTRODUCTION:
The Redback Impedance Meter is an absolute necessity for all PA system installers. An impedance meter is critical for
accurately measuring low impedance loudspeaker systems, incorporating multiple speakers and crossovers, and for measuring
commercial 70V or 100V line speaker systems, which may include many speakers with line transformers and several hundred
meters of cable. Trying to measure this type of load is virtually impossible with a standard multimeter.
The Redback® Q 2004 measures and calculates loads for both 100V and 70V line systems up to 5k Watts in power. Most
impedance meters on the market display the impedance in ohms, leaving the installer to calculate the system wattage. This
impedance meter for ‘dummies’ designed and manufactured by Redback calculates and displays speaker loads in watts.
Measuring a transformer with a regular ohm meter or multimeter is very difficult and provides inaccurate results. This is
because an ohm meter or multimeter uses DC to measure the resistance. Consider a transformer, which is basically a coil of
wire, the DC resistance will be fairly low. If an AC signal is passed through the winding, the impedance will be much higher,
unless the winding is shorted. In this case the reading will be very low.
In the case of a short circuit the inductance of the transformer tries to impede the current flow through the winding. The
nature of transformers will result in the impedance being reflected into other windings on the transformer being tested. This
means a shorted turn on any winding will show up on the other windings.
For example a short circuit on several hundred metres of cable will not show up as a short circuit on a standard multimeter.
You will actually measure the DC resistance of the cable which will be around 22 ohms for 500 meters of 24/0.2 cable.
Using an impedance meter, measuring the AC resistance will read a short circuit. A short circuit located remotely in a speaker
line is the major cause for amplifiers overheating and blowing DC fuses.
Shorted turns on mains transformers primary windings can also be measured with this meter. If this meter displays a value
of less than 100 ohms, this will indicate that the transformer has a shorted turn.
Operating Manual
Q 2004
Impedance Meter
1.0 FEATURES:
• Suitable for 50V, 70V and 100V line speaker systems up
to 5kW
• Also suitable for measuring low Impedance speaker loads
of 4 -16Ω
• OLED display shows Impedance and Wattage of the load
• 1Ω to 20KΩ test range
• Auto ranging
• Display ac/-10%
• Push button operation
• System Check Mode (20, 60 or unlimited minutes)
• 5V Rechargeable Lithium Polymer internal battery
• Low battery indication
• Buzzer and Haptic feedback option via Menu access
• USB Charging lead supplied
• Silicon Test Leads supplied
• Soft Carry Case Included
• Rugged yet easy to hold compact hand held case
User manual revision number: 1.0
03/12/2020
