© 2003 Wohler Technologies Inc. ALL rights reserved
10
AMP2A-4S
and
AMP2A-10S
User Manual P/N
821554
Rev-
B
Please refer to Figure-2a on the following page to familiarize yourself with the front panel features of the AMP2A-4S and AMP2A-
10S units. The following sections describe these features and are referenced, by number, to Figure-2a.
Front Panel Features
Section 2: Operation
1
2
3
4
5
6
7
8
Speakers
The AMP2A series internal speaker system is comprised of two mid-range tweeter speakers (left and right) and one woofer
speaker (center). The two side channel speakers reproduce, in stereo, only the mid and high frequencies.
Power Indication LED
This LED glows green to indicate the AMP2A series unit is connected to mains power and an operation voltage is present.
Audio Level Meter LED Bargraph Displays (1-2)
Audio levels for the selected 2-channel source are visually displayed via these two 20-segment, tri-color LED bargraph
meters. Dynamic range for these meters is 44 dB and they are able to display signal levels using either PPM or VU standards.
Input Level Gain Calibration
and
VU/PPM Display Mode
for each of the two meter bargraphs is user selectable via two
DIP switch modules accessible through the top cover of the unit (see page 17 for DIP switch settings).
Contact the factory for additional information concerning meter scales and ballistics.
Volume Control Pot
This controls the loudness of the audio reproduced by the internal speakers or connected headphone. Clock-wise rotation of
this control increases the loudness of the monitored audio.
Headphone Jack
Select the headphone audio sources as you would for the internal speakers. When you plug in headphones, the speakers will
mute. This jack accepts a standard 1/4” phone type stereo plug.
Phase Indication LEDs
These three LEDs offer instant verification of phase (polarity) conditions in the pair of channels selected for monitoring in
the Left/Right channel speakers. There are three LEDs; the two smaller LEDs labeled "
FAST-IN
" and "
FAST-OUT
" show
instantaneous phase relationships in the signal, while the larger LED, labeled "
AVG
", will indicate the
average
phase condition.
The small "
FAST-IN
" LED glows (or blinks) GREEN when signals are
in-phase
. The small "
FAST-OUT
" LED glows (or
blinks) AMBER for
out-of-phase
signals. The larger "
AVG
" LED indicates the
average
phase condition by glowing GREEN
for
in-phase
conditions, or RED for
out-of-phase
conditions. In general, it is sufficient to regard the "
AVG
" LED (average
phase condition) as adequate for proper phase monitoring. While it is normal for stereo signals to contain some intermittant
instantaneous out-of-phase and in-phase conditions (small LEDs), a steady red glow of the larger LED almost always indicates
an out-of-phase alarm condition.
Balance Control Pot
This control pans the volume balance between the left and right speakers.
Source Select Switch
On the
AMP2A-4S
model, this 4-position rotary switch selects one of
four
stereo pair inputs for monitoring through the
speakers (or headphones) and level meters. The numbers on this switch correspond to the numbers silkscreened above the
Analog Input Connectors
on the rear panel (Item C, page 12).
On the
AMP2A-10S
model, this 10-position rotary switch selects one of
ten
stereo pair inputs for monitoring through the
speakers (or headphones) and level meters. The numbers on this switch correspond to the numbers silkscreened above the
Analog Input Connectors
on the rear panel (Item C, page 12).
