8
© 2006 Wohler Technologies Inc. ALL rights reserved
AMP1A-4S/-10S/-LP4S/-LP10S
User Manual P/N
821527
Rev-
B
Please refer to
Figure-2a
on the following page to familiarize yourself with the front panel features of the
AMP1A Series
units covered
by this manual. The following sections describe these functions and are referenced, by number, to
Figure-2a
.
Section 2: Operation
Front Panel Features
1
Speakers
The
AMP1A Series
internal speaker system is comprised of two mid-range tweeter speakers (left and right) and two woofer
speakers (left and right). The two mid-range speakers reproduce, in stereo, only the mid and high frequencies, while the two
woofer speakers monorally reproduce the low frequencies.
2
Volume Control - Rotary 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.
3
Headphone Output - 1/4" Jack
Select the headphone audio sources as you would for the internal speakers. When you plug in headphones, the internal
speakers will mute. This jack accepts a standard 1/4” phone type stereo plug.
4
Power Indication - Green LED
This LED glows GREEN to indicate the
AMP1A Series
model is connected to operational mains power.
5
Balance Control - Rotary Pot
This pans the volume balance between the left and right speakers. If the balance is adjusted hard left or hard right, a slight left/
right channel mix is retained (only in low bass frequencies) so that phase discrepancies can be discerned.
6
Source Select Switch - 4-Position or 10-Position Toggle Switch
This switch selects, from the multi-channel inputs, a single stereo audio source (2 channels) for monitoring through the unit.
The
4S
models use a 4-position rotary switch for source selection, while the
10S
models use a 10-position rotary switch for this
function.
7
Audio Level Meters - 10-Segment LED Bargraph Displays
(AMP1A-LP4S and AMP1A-LP10S Only)
Audio levels are visually displayed via these two 10-segment, tri-color (red, amber, green) LED bargraph display level meters.
Bargraph
1
monitors Channel
A
(left) while Bargraph
2
monitors Channel
B
(right). These meters are able to simultaneously
display signal levels using both PPM and VU standards. Alternate display modes are user selectable via a DIP switch module
accessible through the top cover. See page
15
for settings and page
16
for specifications of these meters .
8
Phase Indication - Bi-Color LEDs (red/green)
(AMP1A-LP4S and AMP1A-LP10S Only)
These three LEDs indicate the
instantaneous
and
average
phase (polarity) conditions between the pair of channels
selected for monitoring in the Left/Right channel speakers. The larger LED labeled
AVG
indicates the
average
phase
condition between the two signal sources. The two smaller LEDs indicate the
instantaneous
phase relationships.
Indication is as follows:
•
The smaller "fast"
in-phase
(Φ
Φ
Φ
Φ
Φ
+
)
LED glows (or blinks) GREEN for
in-phase
signals.
•
The smaller "fast"
out-of-phase
(Φ
Φ
Φ
Φ
Φ
-
)
LED glows (or blinks) YELLOW for
out-of-phase
signals.
•
The larger
AVG
LED indicates
average
phase condition; GREEN for
in-phase
signals, RED for
out-of-phase
signals.
In general, observing the
AVG
LED alone is sufficient for proper phase monitoring. While it is normal for stereo signals
to contain some intermittent instantaneous
out-of-phase
and
in-phase
conditions (
FAST
LEDs), a steady RED glow of
the
AVG
LED indicates an
out-of-phase
alarm condition.
