71 radio install
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 1,140
Likes: 96
From: Naples
Melting Slicks
Joined: Mar 2005
Posts: 2,094
Likes: 298
From: Midlothian VA
You can pull it from the BAT on the fuse block OR if you can reach it you can tie into the hot for the cigar lighter.
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 1,140
Likes: 96
From: Naples
Le Mans Master
Joined: May 2003
Posts: 8,876
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
The "modern" radios use the +12 constant not just for memory but to POWER the radio. The red (ignition)wire is just a trigger wire and does nothing but turn on the radio.
This was done for two reasons-
1) To help keep noise out of the audio- as the battery - constant +12V is usually cleaner- and if noise is present in the system -a simple solution most of the time is run a wire directly to the battery. This helps eliminate the noise as the battery acts as a filter. Using the ignition as a power source- isolating it is a lot more involved. Also a winner for the manufacturer - as only one noise filter is required- where as previously (15-20 years) two were needed. As in the C3, the wiper is on the same circuit as the radio (yellow wire) and noise could easily be introduced into the power line.
2) In most installations- the constant source is usually a more "robust" circuit- or a higher current- larger gauge wire used -as in the cigarette lighter/courtesy lights as on the C3.
So if you have noise- go to the cleanest power source- the battery- just make sure you fuse the wire AT the battery.
Richard
This was done for two reasons-
1) To help keep noise out of the audio- as the battery - constant +12V is usually cleaner- and if noise is present in the system -a simple solution most of the time is run a wire directly to the battery. This helps eliminate the noise as the battery acts as a filter. Using the ignition as a power source- isolating it is a lot more involved. Also a winner for the manufacturer - as only one noise filter is required- where as previously (15-20 years) two were needed. As in the C3, the wiper is on the same circuit as the radio (yellow wire) and noise could easily be introduced into the power line.
2) In most installations- the constant source is usually a more "robust" circuit- or a higher current- larger gauge wire used -as in the cigarette lighter/courtesy lights as on the C3.
So if you have noise- go to the cleanest power source- the battery- just make sure you fuse the wire AT the battery.
Richard
