Monday, October 1, 2012

When speakers stop speaking


Is the radio in your vintage car sounding tinny, scratchy, or generally awful?  If the vehicle is all original, and it’s more than 10 years old, there’s a good chance your speakers are shot.

Even if the car is hardly driven at all speaker cones are prone to dry out and fail.  The part that fails is generally the surround, which is the bit that connects the main body of the cone to the frame.




Take a look at these two photos and see the difference – one shows a good surround, while the other shows a surround that has fallen to pieces.  In this speaker the surround was made of foam, and the foam turned to dust and vanished.  When the speaker is played it will sound terribly scratchy because the voice coil (hidden under the cone) is scraping the frame.  If left unrepaired the coil may short out, and damage the radio electronics.

Interestingly, the speakers most prone to failure are those made with foam surrounds in the 1980s and 1990s.  Older speakers had rubberized cardboard surrounds, or simple paper, and they fare batter with time. 

And time isn’t the only thing that kills speakers – volume will do them in, too.  When you play the radio loud the speaker cones are pushed in and out greater distances, which stresses the cones and surrounds and will eventually lead to failure.

Speaker technology has improved quite a bit in the past decade, which means the speakers you can buy today are far better than what was in the older cars.  For that reason we tend to turn to suppliers like Crutchfield rather than buy oem from the carmaker.

If you are changing speakers in a 1970s car (or something older) you may find there’s only one wire to the speaker.  In those installations the other terminal on the speaker is connected to ground.  When wiring the speakers you’ll see the terminals marked in red, or with a + sign.  Ground the black or – terminal.

The polarity of speakers is important whenever there is more than one installed in a system.  When they are the same, they are said to be in phase, and they reinforce each other   When they are backwards they tend to cancel each other out.  Out of phase systems tend to sound tinny and faint.

Look at the speakers you are replacing and make sure the polarity is the same when you connect the wires to the new ones.

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