Owner's Manual

AtlasSound.com – 12 –
Owner’s Manual
AA400PHD
400W Mixer Amplifier
1601 Jack McKay Blvd. • Ennis, Texas 75119 U.S.A.
Telephone: [phone] • Fax: [phone]
Using the PHD Mixer Amplifier Diagnostic System
The AAPHD Series features a patent pending Amplifier Self Diagnostic System. The PHD (Push Here Diagnostic) is simple to use and
is very effective running a system diagnostic test to assure the amplifier has the proper load applied. The proper load will assure a long
lasting trouble free audio experience with your new AAPHD Series amplifier. Many amplifiers fail because an incorrect load is applied
to the amplifier. This is especially true when using the amplifier in a 25V or 70V distributed audio speaker system. There are a few
common failure points that can occur during system installation that are listed below.
Common Amplifier Failure Conditions, also see “How to Trouble Shoot Your Speaker System if the Limit LED is Illuminating”.
1. A short in the speaker wiring.
2. Improper load selection or power tap setting on 70V speaker systems. It is very common when using many speakers to
have one of the speakers tapped accidently at 81. This error will definitely be very hard on a 70V amp and in most
cases cause the amp to fail within a few days. This kind of error is easy to make, time consuming to find and costly to fix.
3. Too many speakers attached or the wrong power taps are selected. If a 100 watt amp is used in a 70V system and it has ten
speakers all tapped at 10W, but three of the speakers are accidently tapped at 30W, that comes up to 160W of power
required to drive the system properly. While it may work at low levels, as soon as the system needs to be louder the
amp will be strained and could fail over time.
Most amplifier failures are caused by improper installation on the speaker side. There are two known ways to test the speaker system
after everything is installed.
A. Measure the speaker system using a true audio frequency impedance meter. These are the best way to see if your speaker
system is wired correctly for the amplifier.
B. Run the PHD Self Diagnostic test.
Running a Self-Diagnostic Test using the PHD Feature
Step 1 - Install the AAPHD Mixer amplifier, connect the input signals. Turn all levels to minimum. Do not attach the speaker system to
the amp at this point.
Step 2 - Install the speaker system per the design, double check speaker tap settings. The total power for all the speakers should NOT
exceed the maximum power rating of the amplifier installed.
Step 3 - Connect the speaker system to the amplifier. Pay special attention when connecting the speaker leads to the proper terminals
on the amplifier.
Step 4 - Turn the amplifier On.
Step 5 - Before starting the system Diagnostic test. Make sure no people are present or near the speakers during the diagnostic test
without taking proper precautions. A 1 watt test tone will be present at each speaker. The audible SPL level will be based on the power
tap setting at each speaker and sensitivity specification of the speaker. The audible SPL level may be alarming to some people. Wear
proper hearing protection before starting the test.
Step 6 - Activate the PHD circuit by inserting a small, pointed tool through the hole on the front panel labeled PHD. Press and hold
the momentary switch for 5 seconds, then release. A test tone will be audible through the speaker system. If the Limit LED does not
illuminate Yellow, the system is properly set up and no errors in the system were found. Continue the installation.
Note: During the initial start of the diagnostic test, the Limit indicator may flash Yellow for a few seconds until an accurate
diagnostic reading has been completed, continue to hold the PHD switch in for 5 seconds to assure the test is complete.
After 5 seconds and the Limit indicator is illuminating Yellow steadily, stop and read the section “How to Trouble Shoot Your
Speaker System If the Limit LED is Illuminating.