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AUTOSOUND 2000 TROUBLESHOOTING TIPS
QUICK CHECK FOR TROUBLESHOOTING CAR AUDIO SYSTEMS
Preface:
All audio systems exhibit noise; however, if the level of noise is low enough, and the signal level high enough, noise should
not be a problem. This means that it is very important that the signal level throughout the system be optimized BEFORE
dealing with your noise problem. Using a scope (or a small portable amplifier) and Track 99 (1kHz at all high bits) of
Autosound 2000’s CD #101, or tracks 24 through 29 of Autosound 200’s CD #102, adjust the system so that when the maximum
usable signal level of the deck is fed into the system, all the preamp level components clip at the same time. However, we
recommend up to as much as a 3:1 voltage overlap with the power amplifiers; i.e. an amplifier with a 2 volt minimum sensi-
tivity can be driven by up to 6 volts of signal.
Noise Overview:
Car audio electrical accessories are notorious for interfering with car audio systems. The interference commonly arises from
three areas:
1) Power line noise (5%), which can be attenuated with in-line noise filters,
2) Inadequate power supply isolation (45%), which can be cured with transformer signal coupling, additional isolated power
supplies, or changing out components, or
3) Inductive interference (45%) - Including loop area inductive noise picked up by the signal cables - which can be remedied
by relocating or rewiring components, rerouting signal cables, or using twisted cable or balanced transmission systems.
page 38
AUTOSOUND 2000 1-2-3 METHOD OF LOGICAL TROUBLESHOOTING
I. MUTE THE AMP(S). Insert a muting plug (shorted male RCA connector) into each amplifier channel. Turn up the amp sensitivity. Start the car
and turn on the headlights, air conditioning, brake lights, etc. Listen for noise in each speaker. Be very picky here!
A. If still noisy, substitute a small test speaker with short leads for the speakers, crossovers, and speaker leads in the car. If still noisy,
substitute an isolated power supply (120 VAC to 13.8 VDC bench supply or a small motorcycle battery) for the car’s alternator. If the
amplifier is noisy with the test speaker, you have a BAD amp. Send it in. It really doesn’t matter if it is quiet or noisy while running on the
isolated supply because you have a BAD amp. Send it in for repair and if it was quiet on the isolated supply, indicate so on the repair tag.