How to Use an MP3 Player Like an iPod in a Car With No Head Unit

iPods, iPhones, Android phones and MP3 players can connect to car amps

When the head unit in your car breaks, or it's just time to upgrade, it may be tempting to just leave the head unit out of the equation entirely and just use your iPod or smartphone. For those of us who use our phones and MP3 players to listen to music and podcasts in our cars anyway, it seems like a natural step.

The problem is that you can't connect an iPod, or any MP3 player or smartphone, to the audio system in your car without a head unit to act as an intermediary. Even with the right iPod adapter in hand, most stock car stereo systems are missing one vital component: an amplifier.

iPod music player on car dash

What You Need to Use an iPod or Phone in Your Car Without a Head Unit

If you want to use your iPod, MP3 player, or phone in your car without a head unit, you can use one of the two following solutions:

Head Unit Replacement Method

  • An amplifier with RCA inputs: You absolutely need an amplifier for this to work. If you don't already have an external amp in your car, you'll have to buy one, and they aren't cheap.
  • An RCA adapter: You can use an RCA adapter that's specifically designed for your iPod, phone, or MP3 player, or use a 3.5mm to RCA adapter.
  • A line driver: This is a component that boosts the signal coming out of your iPod. You may not need one, but it depends on your amplifier.
  • An equalizer: You may be able to get away with an equalizer app on your MP3 player or phone, but a physical equalizer component will almost always provide better sound.
  • Wires and cables: You'll need to connect the audio components to power and connect your MP3 player to the audio components.

External Speaker Method

  • An external speaker: Choose a speaker that runs on 12V so that you don't have to worry about batteries, and make sure it has the physical or Bluetooth connectivity that matches your iPod, phone, or MP3 player.
  • Mounting hardware: You'll need some method to mount your speaker where it won't be in the way or block your view of the road.
  • Cables: If your speaker uses a physical connection, you'll need the right cables to connect to your iPod, MP3 player, or phone.

Using an MP3 Player Like an iPod or Smartphone Without a Head Unit

Unfortunately, there’s no easy way to bypass your head unit, connect a phone or MP3 player, directly to the speakers in a car, and have it work the way that you probably want it to.

While it is technically possible, there are no iPod car adapters on the market that will get the job done. To accomplish this type of project, you would need to essentially build your own head unit replacement, at which point might be better off just buying a cheap head unit with an auxiliary input.

For a little more money, you'll get even better sound if you find a new head unit you can afford that includes a USB port or any kind of direct iPod control.

Why Head Units Are Necessary

The problem with using an iPod without a head unit, and the reason there isn’t an adapter designed to do it, is that iPods aren’t designed to drive speakers.

At first glance, it seems like there shouldn't be a difference. You can plug headphones or earbuds in and it works just fine, and you can plug your iPod into your car or home stereo without a problem, so what’s the big deal?

The crux of the issue is that it takes a lot more power to drive speakers than it does to drive headphones or earbuds, and your iPod or phone just isn’t up to the task.

When you plug an iPod into a head unit, one of two things happens. Either the head unit passes the audio signal through an internal amplifier before sending it to the speakers, or it transmits the unamplified signal to an external power amp. If you have a stock car audio system, then it’s a safe bet that you’re dealing with the former.

In some cases, it's even more complicated than that. For instance, if you connect your iPod via a USB or proprietary cable, it may send digital information to your head unit instead of an audio signal.

That allows the head unit's built-in DAC to convert the digital file into an analog signal, and then either amplify it internally or forward the signal to an external amp.

So What About iPod Car Adapters?

There are a lot of different iPod car adapters out there, but they all do the same basic thing: pass an audio signal to a head unit so that it can be amplified and sent to the speakers. Whether you use a cassette adapter, a dock, a lightning connector to 3.5mm jack, or even a specialized direct iPod control cable, that’s all that’s really at work.

If you want an iPod car adapter that will bypass your head unit and actually work, then you need to have an amplifier somewhere in the equation.

The easiest way to accomplish this is to just install a power amp that has RCA inputs. You can then use a 3.5mm TRS to RCA cable to connect your iPod or phone to the amp. You may also need a line driver or physical equalizer to achieve the sort of sound quality you would expect if you had a nice head unit to work with.

Depending on whether you already have an amp with RCA inputs in your car, and if you can get away without using a line driver, then this is actually a low-cost option that’s definitely worth trying. Otherwise, you’ll probably have better luck picking up a cheap head unit that has an auxiliary input.

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