5
To route the audio signals, the ABX Comparator uses passive circuitry comprising relay switches controlled by
the internal microcontroller. To avoid any possible coloration of the audio and to allow bidirectional signal flow
(because testing of line-level devices uses a different hookup configuration than testing amplifiers does), no
active circuitry is used in the test signal path.
THE REMOTE CONTROL
The handheld remote control, shown at left, communicates with the ABX via encoded infrared
light. The remote duplicates four of the ABX’s front panel buttons:
UNIT A
,
UNIT X
,
UNIT B
,
and
ENTER
. Although the listener could enter his or her choices for each trial using the front
panel buttons, it’s probably much more convenient to use the remote from a comfortable listening
position.
The ABX can also operate without the remote control.
A
X
Enter
B
III. SETTING UP
AN AMPLIFIER TEST
The diagram on the following page shows how to wire the ABX Comparator and the other components needed
for a listening test of two 2-channel amplifiers.
In addition to the ABX unit, you will need the following:
•
A high-quality line-level stereo signal source, such as a CD player.
•
Two 2-channel amplifiers, designated A and B, to be tested.
•
One pair of high-quality speakers, with a power handling capacity suitable for the amplifiers and
intended listening level.
You will also need the following cables:
•
A pair of shielded audio cables for connecting the signal source outputs to the ABX line-level inputs.
One end of each cable must have a connector suitable for the source device, and the other end must
have either a male 3-pin XLR or a male ¼-inch (6.3 mm) TRS connector for the ABX unit.
NOTE: For best results, the signal source should have balanced outputs, and all line-level
signal cabling should be balanced as well.
•
Another pair of shielded audio cables for connecting the ABX to Amplifier A’s inputs. One end of each
cable must have a connector suitable for the amplifier’s inputs, and the other end must have either
a male 3-pin XLR or a male ¼-inch (6.3 mm) TRS connector for the ABX unit.
Summary of Contents for ABX Comparator
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