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4. Substitute a different, known working source
component into the amplifier, especially one with
variable volume. If the second source does not have
variable volume, then reduce the amp’s volume
controls to prevent overdriving the speakers before
playing the alternate source.
5. Test the speakers with a different, distortion free
amplifier or pair of channels on the amplifier. If
the distortion remains, then the speakers are likely
damaged and need to be replaced. Before playing
the replacement speakers, please review the chapter
entitled, ‘Protecting Speakers From Becoming
Damaged’.
6. Disconnect the Speaker Block Connector, loosen
the screws, remove the speaker wires and substitute
a test speaker and two conductor wire. Plug the
speaker block connected back into the amplifier and
turn the power back on. If the test speaker does not
have distortion, then the problem is in the wiring
leading to the zone or in the zone speakers.
7. If the connections on the Speaker Block Connector
are correct, both channels of the RCA cable are
working and distortion free, the source into the amp
is not distorted but the local test speaker is distorted,
then an internal fault has occurred in the amplifier.
TROUBLESHOOTING: HUM
Hum is defined as a constant 50Hz or 60Hz tone and its
related low harmonics (buzz).
Potential Reasons
•
The introduction of a satellite receiver or cable box
into the audio system can cause a ground loop,
resulting in audible hum.
•
The speaker or the speaker wires are in very close
proximity to the transformer in the low voltage
lighting system (< 6”/152.4mm).
•
The amplifier has a different AC ground potential
than the other audio/video components.
Steps to Resolve
1. Turn off the amplifier before connecting or
disconnecting any cabling.
2. Temporarily reduce the audio system to a bare
minimum for troubleshooting. If the amplifier is
connected to an audio system with an AV receiver,
cable box and/or satellite receiver, then turn off the
receiver. Disconnect the line-level inputs.
3. With all the line-level inputs disconnected, is the
hum still audible through the speakers? If yes and
the amplifier is mounted in a metal rack, uninstall
the amplifier from the rack and place it on the floor.
With its inputs disconnected and the amplifier
not physically grounded to the rack, then the hum
should disappear. If it does not, then there may be
an internal fault in the amp.
4. Connect a mobile audio device using its headphone
output with a ‘stereo mini to two RCA male adaptor
cable’ into the amplifier channels with the hum. A
phone with stored music is an ideal source since it’s
not connected to the local AC ground. A CD, music
streamer, or another audio source with a two prong
AC plug can also be used if an iPhone is unavailable.
5. Turn the amplifier back on, play music at typical
volume level and then pause the music. If the hum is
gone, then the problem is likely caused by a system
ground loop. One method of eliminating the hum
is with a ground loop isolator with RCA inputs and
RCA outputs.
6. If the hum is still present, consider temporarily
using an AC ‘cheater’ plug, also called a three to
two AC adaptor. This will lift the AC ground from
the amplifier. Do not leave this adaptor in place
permanently as a safety precaution. If lifting the AC
ground solves the problem, consider using an AC
hum eliminator/lifter on the component introducing
the hum to the system.
7. If any of the in-ceiling speakers are close to the low
voltage lighting transformers, then the speakers will
need to be moved, the transformers moved away
from the speakers or at least the crossovers on the
speakers will need to be moved. The inductors in the
speaker’s crossover network can pick up low voltage
lighting transformer hum if they are close together.
TROUBLESHOOTING: NOISE
Noise is defined as any undesirable sound added to the
input signal. Except hum or its related harmonics. Please
see the above troubleshooting section regarding hum.
Potential Reasons
•
The source providing audio input to the amplifier has
noise and the amplifier is reproducing it.
•
Poorly shielded or defective line-level RCA cables
between the audio source and the amplifier.
•
Damaged speaker voice coils and/or suspension
components (torn spider and/or woofer surround)
can result in a ‘popping’ or ‘cracking’ sound.
•
Drywall debris, insulation or other extraneous
material has fallen into the speaker and resting
against the backside of the woofer cone.
•
An improperly terminated two wire speaker
connection in which strands from one wire are in
contact with the second wire.
•
The amplifier has an internal fault.
Steps to Resolve
1. Turn off the amplifier before connecting or
disconnecting any cabling.
2. Connect a different, low noise audio source into
the amplifier channels with the noise. If the noise
disappears, then the source has the noise and not
the amplifier.
