Classic cars are admired for their craftsmanship, curves, and character — but when it comes to modern car audio, they often present one frustrating problem: RF (radio frequency) interference. That familiar crackle, buzz, or whine that invades your speakers can take the joy out of an otherwise flawless restoration. At Vintage Car Radio, we know how irritating it is to spend time and money on a premium system, only to hear unwanted static the moment you turn the key.

Let’s look at what causes RF interference, how it affects your system, and most importantly — how to eliminate it.

RF interference happens when external electrical signals disrupt your radio or amplifier’s ability to process clean audio. In older vehicles, shielding and grounding weren’t designed to handle the electromagnetic noise created by modern electrical components or upgraded charging systems.

This interference usually enters your system through power, ground, or antenna lines, and it can vary from a light hum to a high-pitched whine that changes with engine RPM.

1. Ignition System Noise
   Spark plugs and distributor systems generate high-voltage electrical pulses. Without proper shielding or resistor plugs, those pulses can bleed into your radio and amplifier circuits.
2. Alternator Whine
   A rising-and-falling pitch that follows engine speed usually points to alternator noise. It enters the system through the power or ground wire when the alternator’s diode isn’t properly filtered.
3. Poor Grounds
   Classic vehicles often have corroded, painted, or weak ground points. This creates voltage differences that lead to static, popping, or whining sounds.
4. Antenna and Wiring Layout
   Long or poorly shielded antenna cables act like antennas themselves — picking up stray RF noise from ignition components, relays, and even LED lighting systems.
5. Aftermarket Accessories
   Modern additions like electric fans, fuel pumps, or USB chargers can introduce electrical noise that wasn’t accounted for in the car’s original design.