User manual

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 (

ΦΦ

Φ+) LED glows (or blinks) GREEN for in-phase signals.

• The smaller "fast" out-of-phase (

ΦΦ

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.