Can I add aux-in to my car stereo?

February 26, 2005 11:36 AM

I have an iPod and a truck with a crappy factory stereo. I have tried 3 different FM transmitters and I'm giving up on using them to play the iPod through the car stereo. If possible, I want to avoid buying a new stereo that has aux-in. It's a big expenses and invites theft. Can I add aux-in to my existing stereo? I've heard that car stereo places will do this, wiring a headphone-jack cable to your seat/dashboard. Is that true? How do they go about it? And how would I "tune it in" after such an installation?
posted by scarabic to technology (13 comments total)

I have the same issue that you have. I have no answer but I have found this article helpful. Eyes on the Road, Tunes in the Ear
posted by MLIS at 11:52 AM on February 26, 2005

Tough question. I know this only tangentially addresses your question, but I've got an aftermarket Pioneer head unit (about 5 years old) that has a CD changer controller port on the back. Pioneer sells an adapter that converts that controller port into a standard RCA cable line-in.

If your factory standard stereo has such a CD changer controller port on the back, the manufacturer (or an aftermarket provider) might make a similar converter.

What make is the car?
posted by socratic at 11:52 AM on February 26, 2005

In an unbelievable coincidence, I just had this done yesterday. They use a FM Modulator which allows you to tune to an unused FM frequency and '"broadcast" to your radio. Since it is hard wired to the antenna jack, it works better than a FM transmitter. They ran a RCA stereo pair to 1/8" miniplug adapter cord and a lighter socket to my center console, along with a toggle switch to turn the modulator on and off.

Several cautions, however. You are sending a signal through the FM tuner, so there is some loss of sound quality. I'm getting some alternator whine, which is noticeable during quite passages of classical pieces or between songs. I'm going back for a noise filter.

Another way is possible if the factory radio has controls for an optional CD changer. Several aftermarket firms make adapter cables that convert the DIN plug that would normally connect the head unit to the CD changer to stereo RCA plugs. You would then change that to 1/8" miniplug and connect your iPod. Better sound quality here, but my stock radio did not have that option

More info here in car audio forum.
posted by fixedgear at 11:55 AM on February 26, 2005

a radio is typically built in sections. there'll be a receiver section that receives signals from the aerial and turn them into audio frequency signals. then there'll be a separate pre-amp stage that has the volume and tone controls, and then a power amp that gives the amplified signal required by the speakers.

some headphone sockets can break a circuit when the headphones are inserted. this is how you get a hifi to automatically cut the signal to the speakers when you plug in your headphones.

what you describe sounds like it could be achived by inserting a headphone socket into the signal path between the receiver and the pre-amp. connected so that when you insert the jack plug to connect your ipod you cut the connection from the receiver.

to do it yourself you'd need to check the logic in what i've written above and, if it makes sense, buy a suitable headphone socket; identify the wire carrying the signal from the receiver to the pre-amp; connect the socket appropriately. there's no guarantee this will work - signal levels might not match up, for example.

i'm only an amateur electronic dabbler. there are some real electronics engineers here, so if one of them replies take their advice over mine...
posted by andrew cooke at 11:55 AM on February 26, 2005

oh well. maybe the reason they don't do what i suggest is that it's all packaged in a single chip these days.
posted by andrew cooke at 11:56 AM on February 26, 2005

You can buy an "EQ"

Also check Crutchfield's "Portable to Factory Radio" section.

As Andrew Cooke said, you'll have a hard time rewiring a stereo to accomplish this. Your best bet cost wise is to buy one of the aux interfaces from Crutchfield or find a head unit that has aux-in built in.
posted by geoff. at 12:03 PM on February 26, 2005

Cool! I think the signal degradation is probably within my tolerance. I found the sound quality of the iTrip to be just fine - except that it fluctated wildly as the car moved around. Hard wired to the antenna sounds like a good way to go about it. I guess I need to start looking for a good frequency for them to set it to, huh? Something that will be vacant throughout my entire commute? That should be fun :)

Thanks all for the answers. I'm off to the boom boom shop.
posted by scarabic at 12:07 PM on February 26, 2005

Holy crap. Crutchfield has the exact part I need, apparently:

Listen to your iPod through the factory car radio in your 1999 Ford Ranger Pickup Super Cab.
posted by scarabic at 12:10 PM on February 26, 2005

I love this guy's little how-to here [for his ford f-150] that covers other issues like mounting and ipod placement, once you get that far.
posted by jessamyn at 12:17 PM on February 26, 2005

For what it's worth, I bought an AIWA stereo the other day and it has an aux-in - I think I got it on sale for $80? So, a new stereo with an aux-in can be had without big expenses.

(I haven't installed it yet though, so can't vouch for the quality...)
posted by sarahmelah at 12:18 PM on February 26, 2005

You are in luck! This will be 'pretty darn close to CD quality.' I had them stuff everything in the center console. This way it is out of sight. They can run a lighter socket to the console or glove box for a few extra bucks.

Here goes a blog link that discusses some of the fancier solutions.
posted by fixedgear at 12:20 PM on February 26, 2005

Wow. I've had an Aiwa with an aux-in sitting in a shoebox ever since I got rid of my old car, at least 4 years ago. Detachable faceplate, and a cool little blinking red light, for security, even. Want it? Shoot me an email.
posted by MrMoonPie at 7:51 PM on February 26, 2005

Followup--I just dropped the stereo (and speakers) off at USPS. Enjoy!
posted by MrMoonPie at 10:03 AM on March 2, 2005