Instruction Manual for LA4 with 1.0.X Firmware – REV A Page 28
Bi-Directional Trigger Applications
Benchmark products support bi-directional
communications over the trigger bus. Any
Benchmark product connected to the bus can
turn the entire system on or off. Because of
the bi-directional design, any power button on
a Benchmark LA4, AHB2, or DAC can be
used to start or stop the system.
The Benchmark device that starts the system
will become the trigger master. If the trigger
master is turned off, all slave devices will
follow. If a slave device is turned off, all other
devices will stay on.
If the LA4 is used to turn the system on, any
connected AHB2 amplifiers will become slave
devices and they can be turned off without
shutting down the LA4.
Slave devices can force the entire trigger bus
to shut down if the POWER button or OFF
button is pressed and held for 3 seconds.
Tip: Press and hold the POWER button on
any Benchmark device for 3 seconds to force
a shutdown of the entire trigger-connected
system.
Trigger Specifications
The Benchmark 12V TRIGGER I/O has a
wide operating range to allow interfacing with
most other DC trigger systems. It should only
be used with trigger inputs that are designed
to tolerate 12 VDC.
• 12 VDC 200 mA current-limited output
• Input responds to 3.3 V logic and
higher
• Maximum input voltage = 30 VDC
• Maximum reverse input voltage = -0.3
VDC
• Input Impedance = 20 k Ohms
• 1/8" (3.5 mm) TRS jack
• Tip = 12 Volt Trigger I/O
• Ring = no connection
• Sleeve = chassis ground
Caution: The 12V TRIGGER I/O is not an
audio connection! This is a 12V DC connection
for synchronizing the on and off sequencing of
an entire audio system.
Tip: The trigger ports can be connected with
2-conductor or 3-conductor 1/8" (3.5 mm)
cables. The 3rd conductor is not used.
Benchmark products are supplied with 3-
conductor cables, but any mix of 2 and 3
conductor cables can be used.
Software Version Identification
The software and firmware versions are
displayed on the ABOUT screen. The software
drives the touch screen and the firmware
programs the Xilinx FPGA hardware control
system. The FPGA controls the power
supplies, trigger ports, rotary volume knob,
remote control and relays. The FPGA has the
speed and precision required to execute
precise timing of the make-before-break relay
closures in the stepped volume control.
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