Radio impedance

[68F250]

Looking thru these TSB’s, I found some interesting tidbits of info. For instance, there’s a big difference between the ’72 AM & AM/FM radios and the ’71 and earlier ones. The speaker impedance changed, ’72 and later radios/speakers are 3.2 ohms while ’71 and earlier ones are 8 ohm. This change also happened on the Bronco, Econoline and all the car lines too. The later radios with the 3.2 ohm speaker output impedance all have a D2 part number.

[Lee]

Hum,

Now that's interesting. I wonder if it has to do with the number of speakers used in the system. Do you know if the number of speakers changed in these years.

If you put two 8 ohm speakers in parallel there overall impedance is 4 ohms.

Then again, maybe Ford got a good deal on 3.2 ohm speakers and bought 10 ga-zillon of them. Ya never know!

Lee

[68F250]

Lee, it says all radios changed and lists a single speaker for the AM radios.

I'm guessing the reason is you can double the power output from the same voltage.

[FORDification]

I decided to add that bit of trivia to the Did You Know box at the top of the page.