Wohler ATSC-1 Manual Download Page 8

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Please refer to Figure 1a on the following page to familiarize yourself with the front panel controls and indicators
of the ATSC-1 unit. The following sections describe the functions of each of the various controls and indicators
found on the front panel. The numbers associated with each heading of the following sections refer to the item
reference “balloon” and leader arrows used in the front panel illustration to point out the locations of the items
described. Reference numbers (front panel) and reference letters (rear panel) are in parentheses when referred to
in the main text.

1 Internal Speakers

The ATSC-1 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. Please note
that the woofer speaker (center) is not a dedicated Center nor LFE speaker. To monitor any one or pair of six possible
input sources to left and right speakers use the right and left speaker select rotary switches (Items 7 and 8, page 10) or
monitor a mix of all channels on both side speakers using the ALL/SELECTED channel toggle switch (Items 9, page
10).

2 Headphone Jack

For critical listening or for listening in high noise environments, use the headphone feature rather than the internal
speakers. Select the headphone audio sources as you would for the internal speakers. When you plug in headphones,
the internal or external speakers will mute. This jack accepts the standard 1/4” phone type stereo plug.

3 Audio Level Bargraph Meter Displays

Audio levels for source channels 1 - 6 are displayed via six 20-segment LED bargraph meters (three on the left side of
the front panel; three on the right side). Dynamic range for these meters is 43dB and they are able to display signal
levels using either PPM or VU standards as set by the user via DIP switches accessible through the top cover (see DIP
swich settings in Fig-1c on page 18). Each meter is labeled on the front panel according to the standard Surround
Sound nomenclature (left front, right front, center, low frequency effects, left surround, and right surround).

Contact the factory for additional meter information concerning meter scales and ballistics.

4 Phase Indication LEDs (Left/Right relationship)

These three LEDs offer instant verification of phase (polarity) conditions in the pair of channels selected for monitoring
in the Left/Right channel relationships. There are three LEDs; the two smaller LEDs on either side show instantaneous
phase relationships in the signal, while the center (and larger) LED will indicate the

average

phase condition. The left

side, or in-phase, LED glows (or blinks) green when signals are in phase. The right side, or out-of-phase, LED glows
(or blinks) amber for out of phase signals. The center 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 center LED (average
phase condition) as adequete for proper phase monitoring. While it is normal for stereo signals to contain some
intermittant instanateous out-of-phase and in-phase conditions (small LEDs), a steady red glow of the larger center
LED almost always indicates an out-of-phase alarm condition.

5 Phase Indication LED (Front/Rear relationship)

This single LED offers verification of the phase (polarity) condition as monitored in the Front/Rear channel
relationships. This LED will indicate the

average

phase condition in these signals by glowing green for in-phase conditions,

or red for out-of-phase conditions. While it is normal for stereo signals to contain some intermittant instanateous out-
of-phase and in-phase conditions (flickering of LED), a steady red glow of this LED almost always indicates an out-of-
phase alarm condition.

FRONT PANEL CONTROLS AND INDICATORS