Oldracerjones

Is there any difference in the switched circuits that would make one better than the others for taking power to my stereo? My initial thought was to take from the closest but wondered if one was better than another. Amps are well below any of the fuses so that should not be an issue.

Mr Nick

For an aftermarket head unit?

Personally, I would use an ignition port on the fuse panel to activate a relay, to keep the power demands from the head unit off the 40 year old wiring harness.

oldcutlass

If it's a low wattage unit or stock any switched source. If it's a high power amp and such, then a separate relay, system powered off the battery with appropriate wire sizes.

jaunty75

Just out of curiosity, why not just use the wire that was originally meant to go to the radio (assuming your car originally had a radio)?

You'll probably want an unswitched wire, too, so that things like the clock setting and station presets aren't lost when the car ignition is off. Things like this weren't an issue with radios back in the day.

Oldracerjones

I like the idea. Thanks.

Oldracerjones

The install instructions specifically call out a switched outlet but it does have a digital clock with a battery backup. That must keep it on track when the car is not running.

Oldracerjones

It is a low power unit, just the base stereo, no power amp. Thanks.

oldcutlass

Aftermarket units use 2 power wires as Jaunty explained earlier. One switched for main power and the other requires power all the time for clock and memory functions.

jaunty75

Then the wire that would have powered the factory radio should be fine. I have a modern head unit (with no special amp) in my '73 wagon, and I just used the regular radio lead for it. No problems.

I don't remember what I connected the power-always-on lead to. Maybe the lead for the clock as my car doesn't have a clock and so it was sitting there unused. This is a function that definitely requires very little power.


I did the exact same thing for my '67 Delta 88 in which I installed an '80s-era aftermarket AM/FM/cassette unit that required both switched an unswitched power. I used the regular radio lead for the switched and the clock lead (as there is no clock in the car) for the power-always-on lead.

Oldracerjones

Thanks for all the input, I pulled out the old reliable test light and searched for a good switched hot. The yellow radio wire is dead. But the 8-track had a hot. Hooked it up and it sounds great. AM/FM sounds good, IPOD, USB and Sirius all sound fantastic. Took it for a short cruise, nice to have tunes while I drive. Now, I'll just load up a couple playlists with all my old cruising music from the 70's.

hookem horns

Orange courtesy light wires are always on and could supply the tiny bit of power needed for the clock/presets on a modern unit. That's what I did and no fires yet :-)