93 Explorer Radio issues

[1st Ford for me]

I just bought a 93 Explorer and the speakers are very quiet and very scratchy like a blown speaker. I navigated to all four speakers individually and they are all the same. Could all four be blown or should I be looking for something else?

 

[J_C]

Use a multimeter to measure for low AC voltage when the radio is playing. You should easily hear sound at 1V, and of course voltage rising as the volume is cranked. You can test with and without the speaker plugged in. If voltage doesn't go up, the amp (or head unit, depending on how it's set up) (or some wiring short) is the problem.

Similarly you can measure resistance of the speaker coil and compare against whatever impedance it's labeled for, is usually a DC resistance measurement a little lower than that, like a reading around 3.5ohm for a 4ohm speaker.

 

[Scorpion8]

Or easier just to plug one "known good" speaker in at one location and if the sound changes at that speaker, it's the speakers. If the sound doesn't change, then it's the amp/head-unit.