Manual

AtlasSound.com – 6 –
Owner’s Manual
AA50PHD
50W Mixer Amplifier
1601 Jack McKay Blvd. • Ennis, Texas 75119 U.S.A.
Telephone: [phone] • Fax: [phone]
Front Panel
1. Power Switch
This push switch (On/Off) supplies power to the mixer amplifier.
2. Power Indicator
This LED illuminates Blue when the power switch is turned On.
3. Signal Indicator
When the signal LED illuminates Green, input signals are connected to the amplifier. The Signal LED is PRE the input level controls.
4. Peak Indicator
The AAPHD Series amplifier has an input signal peak limiter located between the preamp mixer stage and the power amplifier stage.
This input signal peak limiter is designed to prevent the amplifier from being over driven by excess input signals that may cause
damage to the amplifier. If the amplifier preamp stage senses excessive input signal, the peak limiter will engage reducing the signal
and the Peak LED will illuminate Red. An occasional flash of the LED is OK. If ON steady state; turn the associated level control down
until the Peak LED turns OFF. It may be necessary to reduce the signal level at the input of the amplifier.
5. Limit Indicator
This LED serves two functions:
A. PHD Test Circuit Load Fault Indicator - When testing the system using the PHD feature for proper wiring and amplifier
loading, this LED will illuminate Yellow if a fault is sensed in the audio speaker system. See “Using the PHD Load Impedance
Testing System.” Note: For 70V distributed systems only.
B. Excessive Current Draw Limit Indicator - Will illuminate Yellow when the amplifier is consuming excessive current. At that
point, a current limiting circuit is activated, reducing the output power to prevent damage to the amplifier. The most likely
cause for the fault is an incorrect load impedance connected to the amplifier. The LED should not come on if a proper load is
applied. If the Limit LED is illuminating, use the PHD Load Impedance test explained in the manual to help troubleshoot the
cause of the problem. Note: An occasional LED flash is okay. When LED is ON audible distortion may be heard at the speakers.
6. PHD Switch
The AAPHD Series features a patent pending Amplifier Diagnostic System. The PHD (Push Here Diagnostic) is simple to use and
very effective in testing the speaker wiring and load impedances on 70V speaker systems to assure the proper load is applied to the
amplifier. Please read the section on “Using the PHD Feature” before activating the circuit. To activate the PHD circuit a small tool with
a point will be required to access the momentary switch through the hole on the front panel. See “Using the PHD Mixer Amplifier Load
Impedance Testing System.”
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