Semi-OT: Car stereos... Easy 1/8" jack solution?

[ExpAnonColin]

I recently got a new car here in CA.  I use an iPod, but the car came with a CD player/radio combo, so tapes are out.  I would use the FM transmitters, but it's a bit much money and they're very unreliable here in busy California.  So, I was wondering if there was any easy way to basically remove the stereo system and find a few wires to use as a stereo 1/8" input, basically so I coudl wire my ipod right into the system.  I could easily build an amplifier, but are there any impedance issues I need to take into consideration? Is it that easy, or not?  Anyone here able to point me in the right direction?

Thanks.
-Colin

[travissk]

I drive a 1991 integra when I'm here at home, and I bike at school in CA, so I might be a little out of date with these matters. I did install my car stereo a few years ago though, so the wiring shouldn't be much of a problem. Depending on manufacturer, I do believe that the amplifier is seperate from the head unit, so you could just connect the appropriate wires (verify this with someone though - this isn't an area I know too much about!)

So I guess the relevant question is - what type of car/stereo do you have? There might be a couple easy ways out... sometimes, if the unit supports an external CD changer, then there will be RCA jacks in the back. You could hypothetically get a converter and wire your iPod to be the CD changer. CD changer interfaces might have changed since a few years ago, but it might be an option.

If you have to hard-wire the player to the car, there will likely be a plastic connector in back. This will vary with every manufacturer; when you buy a stereo you usually have to buy an adapter to connect to your OEM stereo (mine's an Aiwa I think, so I got the Accura/Honda to Aiwa adapter). My advice if you have to get this drastic is to buy the cheapest one of these you can find that accepts your car's maker on the one end, then chop the other end off and go from there. Therefore you won't be ruining anything, and it should only set you back $6 or so.

Things to watch out for - some newer stereo units have factory security settings designed to keep people from stealing the unit and owners from modifying things . I don't know what they do; mine doesn't have them since it's old, and for all I know it could be a scare tactic rumor used to push the higher-end manufacturer stereos at the time of purchase.

Also, your iPod will be running on batteries, and -might- cause some problems with multiple grounds. I'm sure there are more car-savvy people around, but I think you run the risk of getting buzzing. The solution is either to ground the iPod to the chassis of your car, or use a cigarette lighter adapter to power the iPod. I have an 1/8" input jack in the front of my car and have used a cheapo Rio Volt mp3 cd player with it and didn't get any interference, so it's probably something to fix if the problem pops up.

I know the radio stations are a lot closer together out there than they are here in the midwest, but radio might be a possible option if your setup is going to force you to crack open all the panels to get to the back of the stereo. The sound quality probably won't be as good as if you go direct, but if it's a temporary car (I forgot, how long are you in CA?), it might be livable.

[Fret Wire]

Email, or better yet, call Crutchfield. They should know just what you need. No need to hack your wiring nowadays, there is usually adapters for everything.

http://www.crutchfield.com/S-wGYDnR7Exau/index.html

[ExpAnonColin]

Fret Wire-I'm not talking about using the current CD player at all, I mean more removing the entire CD player that's in there and replacing it with nothing but a 1/8" jack.  I wouldn't have the radio whatsoever.  I already have a car adapter for the iPod, so I'm good in that respect.  If I was to remove the CD player, would it be self explanatory as to what I need to connect where for just setting up an 1/8" jack?  It doesn't look like crutchfield has what I'm looking for.

-Colin

[Fret Wire]

So, I was wondering if there was any easy way to basically remove the stereo system and find a few wires to use as a stereo 1/8" input, basically so I coudl wire my ipod right into the system.  Thanks.
-Colin

"Find a few wires"? I think Crutchfield does have something you're looking for, the wiring harness layout for your car, and advice on how to do it. Most of the time, they can tell you over the phone what color wires on the factory harness are which. Many times you can't trace the wiring off the harness plug by color. Are you familiar with Crutchfield? They are the biggest seller of DIY car system kits, and have adapters and wiring schems' for most every model car out there. They handle hook-up and installation question's on the phone all the time. Call their installation hot line, nothing to lose but five minutes of your time.

[SoundTech]

Most factory systems have everything built into the unit, including amplification.  If you pull the entire unit, you're left with an antenna connection, +V and ground to your battery, and speaker wires.  You'd need to inject the line level audio from the iPod into the existing stereo, or get an amplifier to go between your iPod and the speakers in your car.

[niftydog]

some stereos actually have RCA line inputs for CD stackers...

[Fret Wire]

Most factory systems have everything built into the unit, including amplification.  If you pull the entire unit, you're left with an antenna connection, +V and ground to your battery, and speaker wires.  You'd need to inject the line level audio from the iPod into the existing stereo, or get an amplifier to go between your iPod and the speakers in your car.

Many times, you'll also find that the harness plug has additional wiring for ilumination, power antenna activate (some), and now that many factory systems have separate amps, an amp switch-on.

[Jason Stout]

...lm386 smoky type amp to speakers.

[Peter Snowberg]

I hope this is more what you're looking for....

Open up the unit and find the power amp chip. Chances are you con't go by numbers anywhere because they'll be custom jobs or house numbered. You want to trace the speaker connections to the power amp chip. There will be two inputs for that amp chip and you may be able to find a couple of coupling caps easily that feed the power chip. Remove the connections feeding the caps and replace them with your line level signals.

Some radios have a volume pot where you could just feed your signal in instead of using the original connection at the CW end. New radios are all based on processors that usually contain a VCA for volume and balance and some filters for EQ. If you tap the signal before that chip you'll get the volume and tone controls. That may also be helpful if the amp circuit is more complex and uses a negative feedback signal injected into some circuitry before the power chip. You also get to mute the system when plugging and unplugging.

The processor chip should be connected to the power amp chip via a couple of coupling caps.... probably electrolytic. This isn't a big chip in most cases.

You may want to build a signal injector. It's like an audio probe in reverse. Rig up a 555 oscillator to make a nice tone and feed pin three to a 10uF cap and then to a 100K pot which has the other end grounded. Connect the wiper to a small capacitor like a 0.1uF. The other side of that cap is your probe. Set the 100K pot to a low value, alligator clip the 555 and radio grounds together, and start injecting tones. You chould be able to find feed points.

When you do, you could probably just add additional caps to connect to your iPod without even removing the existing ones, but a DPDT switch would be better still.

Good luck and may the force be with you.
-Peter

[SoundTech]

Many times, you'll also find that the harness plug has additional wiring for ilumination, power antenna activate (some), and now that many factory systems have separate amps, an amp switch-on.

Yes, but the +12 for memory, the illumination, and the power antenna are superfluous to this situation.  As for having a "separate" power amp, I've seen units with additional inputs to the unit, but not so much having one enclosed unit for preamp, and a separate enclosed unit for power.  The power amplification is done inside the stereo unit.

[Fret Wire]

You missed my meaning. Have you actually installed any systems? Most  head units do have an integral amp, and all have pre-amp outputs for an external, added on amp. They also have a separate lead for the external amp power-on switch. This does what it sounds like, turns the amp on and off with the reciever. Every external amp has this lead. Every reciever with amp out puts also has this switch. You surely would have noticed this if you installed one before.

As far as being "superflous" to the situation, read the original post. When someone doesn't know any of the wiring in the reciever plug harnesses, that tells me that they have to indentify every lead on the harness before they proceed, regardless of the lead's function. An alternator and 12v car battery are a little less forgiving than a 9v battery.

[nirvanas silence]

Fretwire summed it up Colin.  Most car stereos have an amp built in.  So plugging your Ipod into your speakers will give you as much volume as with headphones.  I did take apart a 1986 Ford Taurus which had a separate amp in the rear, but that was a rare case.  Find out if your deck has an amp and take it from there.

If it has an amp built in to the deck: you either buy an amp from a store ($100+) or build one.  Or just use the one in your existing deck and do what Mr. Peter Snowberg has said.

If it doesn't have a built in amp:  Hook up the Ipod directly to the wires there and you are good to go.

[ExpAnonColin]

Thanks guys.  I'll go try to pull the deck out now.

-Colin

[SoundTech]

Have you actually installed any systems?

Yes.  Not many, but yes.  And in each case, the factory unit and factory wiring harness were not set up to easily accept external line sources for the power amp, and did not have a separate power amp unit installed in the vehicle.  

As far as being "superflous" to the situation, read the original post. When someone doesn't know any of the wiring in the reciever plug harnesses, that tells me that they have to indentify every lead on the harness before they proceed, regardless of the lead's function. An alternator and 12v car battery are a little less forgiving than a 9v battery.

As far as ID-ing stuff, you're right.  But I figured Colin was smart enough to try to find a pinout first before messing with the factory wiring.  I also believe him to be smart enough to not work on the vehicle electrical system with the battery still connected.  Don't work on AC with the breaker on, don't work on "higher" current DC with the battery connected.  Good general rules of thumb.

[ExpAnonColin]

I did it, really what I was wondering initially is, "Will it be easy to pull the thing out and find the speaker wires?", and it was.  But I do need an amplifier, I'll build one today.

-Colin

[Marek]

Here, this comes handy:

ttp://kitsrus.com/pdf/k115.pdf  (PDF!)

http://kitsrus.com/jpg2/k115_pcb.jpg

All you have to do afterwards is - to find the speaker lines in the back of the car hi-fi...

Greetings,
Marek

[nirvanas silence]

Is that really going to be loud enough?

[ExpAnonColin]

Is that really going to be loud enough?

The thing by itself isn't.  At this point I've tried some LM386's as well as a simple transistor amplifier, the 386's were too unstable and the transistor amplifier I hadn't biased correctly.  I'm going to see if I can get some other, better, amplifier chips running.

-Colin

[afranks]

I'm in the process of doing something similar to what you describe to my VW GTI.  Since mine already has a pretty good Monsoon audio system, I'm leaving it put.  Many of the OEM head units out there have a CD changer input, and if yours does, you can often buy an adapter that converts the CD changer input to an auxiliary input.  For many cars, it's not a simple matter of finding the right pins on a connector... there are actually some messages that get exchanged between the head and the CD changer.  The adapter fools the head unit into believing that a CD changer is connected, and will then pass the input signal to the power amp.  If you go to http://www.blitzsafe.com, you can look to see if they make an adapter for your vehicle.  I'm using such an adaptor, along with a powered cradle from http://www.seidio.com which has an articulated arm with a cigarette plug on the end.  It's a more expensive solution, but I like the Monsoon head/amp combo, and short of voiding its warranty, this seemed like the way to go.

-alan