Add Bluetooth To Older Cars With The Best FM Transmitters We’ve Tested
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Any car that’s equipped with a radio and auxiliary power outlet can use a Bluetooth to FM transmitter to wirelessly stream music through its speakers. This 2-in-1 gadget serves as both a phone charger and signal converter—taking in audio from a source like your phone or storage device, then relaying sound to an FM radio frequency. Best of all, Bluetooth to FM transmitters are both affordable and plug-and-play, so they’re set up and ready to go in under a minute without any installation required.
Converting Audio To An FM Frequency
If you’ve ever been to a drive-in theater or cruised through a holiday light show you may recall having to tune your car radio to a specific frequency to play synced up audio through your cars speakers. Behind the scenes an FM transmitter is transforming the audio output from a source like a computer or auxiliary connection to analog sound waves. Bluetooth to FM adapters work the same way, but at a smaller scale than commercial transmitters which can extend for hundreds of feet. Their range is typically limited to the proximity of your vehicle. These models relay audio from inputs such as a Bluetooth connection, auxiliary port, or SD card. Some models even support listening to music stored on a USB flash drive.
How To Use A Bluetooth To FM Transmitter
After plugging an FM transmitter into your auxiliary power outlet (commonly referred to as a cigarette lighter) you'll need to find an unoccupied radio station. Scroll through channels until you find one filled with the crackling static of white noise. This indicates a weak signal that’s ready to be overtaken by the transmitter. In our experience the lowest frequencies (usually between 88-95 FM) work best since they’re often the least saturated. Once you set the adapter to this empty station you should hear silence which means you’re connected. Now you can play audio clearly through the speakers. As you drive through a major city you may notice competing broadcasts break through so you might have to adjust stations more frequently.
How We Tested
We plugged the best-selling Bluetooth to FM car adapters into an SUV using the same lighter port and radio station. We assigned a score to design, features, and, most important, sound quality. We drove around with each model for a week to get a general baseline for everyday performance. Next, we benchmarked their signal strength by tuning into a channel with a strong frequency to see which models were strong enough to beat out those waves, while analyzing sound quality for static or imperfections. Lastly, we measured the built-in microphone clarity and quality by comparing recordings through the voice memos app.
Nulaxy KM18
Bluetooth Car FM Transmitter Audio Adapter
amazon.com
$19.99
amazon.comThe KM18 sticks out from the rest of the pool; figuratively for its high level of audio performance, but also literally thanks to the long neck behind its display. This flexible extension is easy to bend so that you can position the screen and controls in a spot that’s easy to reach while driving. The multi-purpose scroll wheel puts call and volume controls at a tap while each button is raised to make navigating frequencies a breeze. Beyond flaunting the most functional design the KM18 sounded the best throughout numerous rides. It most accurately reproduced audio by picking up little details like background effects with little to no distortion.
Sound quality on the KM18 is sharp—songs have no noticeable tinniness, vocals are full, and bass thumps without warping. There’s no distortion or static—even when we cranked our radio to maximum volume we still didn’t notice a hiss prevalent on others. And while parked for the signal strength test the KM18 completely hijacked a radio station already in use while offering the strongest connection. But, when a signal is really powerful, like we experienced when passing by a local college‘s radio tower, some light crackles broke through. More often than not, the connection was rock solid. While traveling, the KM18’s microphones offered the clearest recordings—minimal background noise and clear pronunciation from each word. If you’ll be taking a lot of phone calls, this is perfect for that.
Overall, this is the most reliable and balanced model we’ve tested. Its screen is easy to read the essential info: station, volume, and connection source. Plus there’s plenty of ways to connect audio, whether you’re using an auxiliary port or old school USB flash drives. We tested the gaudy gold model to spice things up, but the KM18 comes in a variety of finishes from dark mattes to the bright glossy options to suit your taste. While it would be nice to have at least two USB charging ports instead of just a single slow 2.1A port at the bottom, its a small compromise for the overall package.
Anker Roav Smart Car Charger F2
SmartCharge F2 Bluetooth FM Transmitter & Car Locator
amazon.com
$19.99
amazon.comAnker’s Roav F2 transmitter offers excellent sound performance, charging speeds, and smart features within a compact body. Its dimensions are too small to house an external screen, and, depending on where your lighter port is, the limited physical controls can be hard to reach while you drive. However, the F2 is a transmitter meant to be set and forgotten—we plugged in our USB charging cables, set the channel, and slid it into the lighter port out of sight and mind. Throughout testing it was mainly controlled from the Roav smartphone app.
From the app, we were able to set the transmitter station as well as volume levels without physical controls. Sound is just as good as our top pick—we noticed the details of each instrument group, from drum snares to the lightest strings, shine through. However, the vocals and podcasts can sound like there’s a slight phone-like filter on them when you listen closely. This transmitter’s output is the weakest of the bunch—it couldn’t put a dent into an existing channel in our strength test and we saw more interference with this adapter than the others. If you often travel through major cities, this model will likely require constant adjustments on the fly. Still, this excels for those looking for a sleek adapter loaded with features. Not only does it offer two USB charging ports but it supports fast charging with an iPhone 13 Pro Max, juicing up three times as fast—an average 1.5 percent per minute, versus 0.5 percent using the standard 2.1A on the other two.
Another smart feature baked into the Roav is the Find My Car feature. This automatically pins your car’s location on a map so you can find it with ease in a crowded parking lot or unknown area. While the microphones automatically filter out background noises from cabin to wind, this comes at the cost of vocals which sound distant and almost processed. While its still quite clear, its not as good as the KM18 if you prioritize hands-free calls.
Jinserta Bluetooth FM Transmitter
Bluetooth FM Transmitter
amazon.com
$19.99
amazon.comThis no-fuss FM transmitter nails the basics: a strong signal and streamlined physical controls at your fingertips. While the other two models here require you to press front and back buttons to navigate songs and channels, Jinserta’s adapter features two dials. This makes shuffling through songs or quickly adjusting volume levels one smooth motion. And when you need to pause or play a song just press the knob. The animated LED neon lights popping from the dials not only look amazing but help you see the controls, especially at night.
On the default sound profile, voices sound clear but instruments tend to come come across a bit hollow. And any song that uses vinyl or crackling in the background (prevalent in rap) creates a more pronounced effect that ends up being too much. But this model’s standout feature is an adjustable EQ which greatly improves sound on a genre by genre basis. You can hear noticeable gains in the percussion in a rock song and richer vocals in pop and hip hop. The transmitter is super strong and overtakes stations in use. For example, we plugged it in and set it to the same signal as a crystal clear talk show. This completely silenced that frequency and allowed us to override it with our music. Removing the adapter returned the show.
Vocals were rich on podcasts and instrumentals were accurate for the most part, but our testing showed the built-in microphone is barely serviceable. It’s plagued by both background noise and poor sound clarity—words sound muddled and distant. Overall this is a good-looking transmitter that works well for those who prefer dial controls and aesthetics.
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