Audio Research LS28, User Manual

Page: 12 / 22

12
Front Panel Controls
The LS28 has two microprocessor-driven
rotary controls and six buttons (Power,
Menu, Enter, Mono, Invert, and Mute).
Left Rotary control (Input Select)
Select input by rotating the control to the
left or right. The screen displays the current
input on the left side of the display.
Right Rotary control (Volume)
Adjust volume (output level) up or down
for both L and R channels. Volume control
is also selectable via VOL UP and VOL DN
buttons on the remote control. Volume
adjustment is indicated in the display
window by numeric digits on 0–103 scale.
Do not turn volume up beyond normal
listening levels when ‘mute’ is engaged to
avoid unexpected or possibly damaging
sound levels. Reduce volume level
whenever changing input sources, even
when muted.
The right rotary control also functions to
change settings when in menu mode.
Power On/Off
Supplies power from A.C. wall outlet
to preamp; indicated by active display
window. The LS28 requires approximately
45 seconds to warm up; this time is
required to stabilize the vacuum tubes. See
‘Start-Up Procedure’ on page 11 for details.
Menu
The menu button enters the setup menu
of the LS28 to allow customizing certain
settings of the preamplifier. See page 15 for
further details about using the setup menu.
Enter
The enter button is used in conjunction with
the Menu button to make changes to the
systems settings of the LS28.
Mono
Toggle between Stereo and Mono output.
Invert
The invert button allows the absolute phase
of the recording to be switched between
‘normal’ (in-phase) and ‘invert’ (180°
inversion).
Mute
When activated, Mute electrically disables
all outputs of the preamplifier; indicated
by ‘MUTE’ in display window, beneath the
volume number. This control should be
activated before switching inputs, changing
connections or shutting down your audio
system to help protect your amplifier and
speakers from unexpected signal pulses.
When deactivated, ‘MUTE’ is cleared
from the display window allowing normal
operation.
Operation