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  1. #1

    Default Buzz/static on AM radio?

    What the heck causes the buzz/static when the stereo is on AM? Thanks.

  2. #2


    In short, electrical noise. Where the noise is coming from could be from numerous sources including power lines and the isolators on power poles, other bad electrical connections in houses and businesses, right down to plasma TVs with poorly designed power supplies. It can also potentially be caused by DC electrical interference from bad connections on the vehicle or spark plug wires that the insulation is failing on.

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 265K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

    There are 10 kinds of people, those who understand binary, and those who dont...

    Remember kids, the only difference between screwing around and science is writing it down- Adam Savage

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  4. #3


    It definitely is something on the vehicle because it's there no matter where I go and it's constant. I've just put new plug wires on it so I can't imagine that being the problem.

  5. #4

    Enkeiavalanche's Avatar
    Join Date
    Apr 2010
    Piermont,NY, back in Northern NJ now, But may be in IL soon....


    I put a HD Tuner in my truck and get most Am Stations in like FM sound...
    08 Z71 Avalanche Mods to date: K&N CAI,Hellwig Swaybars and End Links, Corsa Sport Exhaust, Superchips Programer,IPCW LOF & 3rd brake light and tails, AMI Gas door,Show Hooks and Door locks, Enkei Wheels, with Pirelli tires, StreetScene Bowties, Grant Steering wheel,Muth signal mirrors,SSBC Big Brake kit,Huskyliner Mug gards,Floor mats and Hood shield, McGard Lug nuts and locks, Bedrug, Cervini's Ram Air hood,35watt HID Fog lights, Sylvania bulbs all around ZXE's Highs and Lows, WhiteNight Back up lights,Sirius and HD Radio, SnugTop sitting on deck now Got a Softopper on now,Tempress Boat Hatches.... New Bilstein shocks are on... New Mods coming soon..... X

  6. #5


    In many cases it comes thru the ignition system, alternator, leaky plug wires, (not the case here) faulty diode, and a host of other sources as mentioned, a quick 20 dollar fix can be found at the local radio shack or stereo shop, what you want is an RFI filter, with AM you can have radio frequency interference, the RFI filter will prevent that from coming thru your radio. Attaches to the radio power in, simple install. fluid filter, air filter, noise filter, man you need a filter for everything these days, lol.
    Life is short compared to history

    Rick (summitwhite11)

  7. #6
    Jr. Engineer poncho62's Avatar
    Join Date
    Sep 2013
    Hanover, Ont, Canada


    Basically, AM is transmitted on a lower frequency than FM and is more susceptible to interference......

    More AM/FM facts

    AM FM
    Origin: AM method of audio transmission was first successfully carried out in the mid 1870s. FM radio was developed in the United states mainly by Edwin Armstrong in the 1930s.
    Modulating differences: In AM, a radio wave known as the "carrier" or "carrier wave" is modulated in amplitude by the signal that is to be transmitted. In FM, a radio wave known as the "carrier" or "carrier wave" is modulated in frequency by the signal that is to be transmitted.
    Importance: It is used in both analog and digital communication and telemetry. It is used in both analog and digital communication and telemetry.
    Pros and cons: AM has poorer sound quality compared to FM, but is cheaper and can be transmitted over long distances. It has a smaller bandwidth so it can have more stations available in any frequency range. FM is less prone to interference than AM. However, FM signals are impacted by physical barriers. FM has greater sound quality due to higher bandwidth.
    Stands for: AM stands for Amplitude Modulation FM stands for Frequency Modulation
    Range: AM radio ranges from 535 to 1705 kilohertz (OR) Up to 1200 Bits per second FM radio ranges in a higher spectrum from 88 to 108 megahertz. (OR) 1200 to 2400 bits per second
    Bandwidth Requirements: Twice the highest modulating frequency. In AM radio broadcasting, the modulating signal has bandwidth of 15kHz, and hence the bandwidth of an amplitude-modulated signal is 30kHz Twice the sum of the modulating signal frequency and the frequency deviation. If the frequency deviation is 75kHz and the modulating signal frequency is 15kHz, the bandwidth required is 180kHz
    Zero crossing in modulated signal: Equidistant not equidistant
    Complexity: transmitter and receiver are simple but in case of SSBSC AM carrier syncronization is needed tranmitter and reciver are more complex as variation of modulating signal has to converted and detected from corresponding variation in frequencies.(i.e. voltage to frequency and frequency to voltage conversion has to be done) which are quite complex
    Noise: AM is more susceptible to noise because noise affects amplitude, which is where information is "stored" in an AM signal. FM is less susceptible to noise because information in an FM signal is transmitted through varying the frequency, and not the amplitude.

  8. #7


    Standard headlights, or an upgrade?

    HIDs can cause the problem.

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  9. #8


    Standard headlights. It's an alpine aftermarket stereo that has been working fine. The problem just came up the last few weeks.

  10. #9


    The lead from the antenna to the radio is shielded co-ax. For the shield to work, the base of the antenna needs to be grounded. Perhaps you've lost the antenna ground.

  11. #10


    Thanks RayVoy. I'll check that out.

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