The 3 Best FM Transmitters

USB port (#): Yes (3) | Bluetooth Connection Confirmation (type): Yes (beep)

The Nulaxy NX12 is a compact FM transmitter with a similar profile to a standard USB car charger. The unit transmits loud, clean sound with strong bass that is amplified with an optional bass booster feature. Despite the compact size, the NX12 sports three ports (a Quick Charge 3.0, Type C PD 18W, and a standard USB port for thumb drives or direct connection of a phone or MP3 player). It also has a volume knob and a channel button and display. Additionally, answering incoming calls is as easy as pressing the volume knob and speaking into the built-in microphone.

While we appreciate the NX12's compact size, we experienced some frustration with the positioning of both the QC and USB-C ports. When the unit is plugged in, these ports are almost flush with the car socket. Accessing them without unplugging the unit is challenging. Additionally, when the NX12 is charging a device such as a phone, it produces a slightly fuzzy sound quality. That said, this transmitter has some of the best sound quality in the class, and the fuzziness is quite mild compared to some other transmitters we tested.

USB port (#): Yes (1) | Bluetooth Connection Confirmation (type): Yes (voice)

The defining feature of the Nulaxy KM18 is its large LCD screen that keeps the user appraised of the volume level, the radio frequency being transmitted, the name of the connected device, and even the voltage of the port that it's plugged into — this last feature is an indicator of the car's battery health. The screen is mounted on a flexible neck that makes positioning it a cinch. Additionally, the unit has a volume knob and track navigation, and radio channel +/- buttons. Rounding out the suite of features is an AUX port (which allows a direct connection to the headphone port of your device), a 5V/2.1A USB port, and a micro SD input for reading MP3 files directly.

This feature-packed transmitter is a bit larger than many of the devices we tested. It's not oversized, but it's not what we'd call low profile. Moreover, the large display screen is a bit heavy for its spindly neck and can result in the unit moving away from you as you push, for example, the phone call receive button. However, the neck's length may be a boon for those with electric sockets deeply set in the car's console. If the Nulaxy KM18's size suits your needs, you'll be happy to know that it delivers a very loud, high-fidelity sound.

USB port (#): Yes (2) | Bluetooth Connection Confirmation (type): Yes (voice)

The Nulaxy NX10 is a screaming deal, by our estimation. It is compact, with an easy-to-use phone answering/volume button/knob, a built-in microphone, and 2 USB ports — one of which is of the Quick Charge variety. As if that wasn't enough, the NX10 boasts tons of flair with its customizable, 7-color LED light spread, including backlit ports. Fleshing out the package is very loud volume and heavy bass transmission that maintains clarity of sound.

Unfortunately, this product is not without its shortcomings. First of all, some people might not like the light show. And, while the color can be changed, the lights can't be turned completely off. Another issue is that the radio frequency adjustment is a bit convoluted, requiring a two-step process. Finally, there isn't an AUX port. However, we think the micro SD card port more than mitigates this lack, making this the go-to budget transmitter.

USB port (#): Yes (2) | Bluetooth Connection Confirmation (type): Yes (beep)

The Sumind Wireless Radio Adapter is a decent quality transmitter with a large LCD screen providing the user with a host of data. Specifically, the screen displays the name of the device connected, the volume level, the radio frequency that the unit is transmitting, whether a Bluetooth connection has been established, and the name of the program being played. The user interface conveniently includes frequency/channel buttons (a feature we really appreciate), track navigation buttons, a volume dial, and phone call receive/disconnect button. There is also a built-in microphone for hands-free calling.

While the Sumind looks much like its higher-end counterparts, it shows its true colors — or sounds, as it were — in its transmission quality. To be fair, the sound is clear, but it is not very loud. Similarly, bass is present but not very strong. Further muddying the sound is a slight fuzziness that increases as the volume is turned up. As a final consideration, the unit is very big — which could be a good thing if your vehicle's electrical socket is deeply set in the console — but, in most cases, it will be an encumbrance. It's our opinion that_for the money—you can do quite a bit better than this device.

USB port (#): Yes (3) | Bluetooth Connection Confirmation (type): Yes (voice)

The AINOPE FM Transmitter is a ho-hum device with marginal test results. It is true that this model boasts 3 USB ports (Quick Charge 3.0, PD 3.0, and type C), Clear Voice Capture (CVC) microphone, and adjustable backlighting. However, these attributes pale when the unit's sound transmission is compared to the leaders in the class.

Unfortunately, the sound quality emitted by this transmitter is fuzzy, bordering on crunchy. Additionally, background static is issued when charging a device through the transmitter. Another concern is the broad user interface capping the socket plug, which may not fit all vehicles. All in all, you can get a much better-performing device for around the same amount of money by choosing one of the award-winning products mentioned above.

USB port (#): Yes (2) | Bluetooth Connection Confirmation (type): No

Unfortunately, the Anker Roav SmartCharge F0 doesn't really live up to its name since it lacks a basic Quick Charge USB port. But, at least the unit has two USB ports, so you don't have to fight with the copilot to charge your device. As an added bonus, this model features an echo-canceling microphone to aid in hands-free gabbing on the phone.

Usually, this is the paragraph where we would list the features that are lacking and the areas where this model fails to meet the standards set by the competition. However, the Anker Roav lacks so many features and transmits audio so poorly that it's better to simply point out that for the same dollar amount you can get a model that works properly. That is to say, a model that delivers loud, high-fidelity sound with a whole lot more features to make your time in the car more enjoyable.

USB port (#): Yes (2) | Bluetooth Connection Confirmation (type): Yes (voice)

The LIHAN Dual USB Port looks a lot like a high-end transmitter, but we're here to tell you that it falls short of this superficial impression. Yes, it has a faux carbon fiber shell that looks snappy, its black with orange accents have an urban flair, and its minimalistic user interface is a nod to Scandinavian design. However, this is where the complimentary critique ends.

At its essence, a transmitter has one job: transmitting audio that is true to its source through a radio frequency that a car stereo can receive. That's it. In our testing, the LIHAN failed to deliver on this modest expectation.

Why Trust GearLab

While our side-by-side testing methodology for FM transmitters was not overly complex, it was nonetheless thorough and revealing. We broke up our analysis into four categories — what we call metrics. Namely, these are sound quality, ease of use, profile, and features. These metrics focus on the fidelity of the audio transmission, the operation of each model, the shape and organization of the interface as well as the pros and cons of the components. In a word, the analysis is exhaustive.

Senior Review Analyst Michelle Powell and Senior Review Editor Nick Miley have long driven cars with outdated stereos that are closer in age to 8 tracks than MP3s. They have bridged this technological gap with transmitters. As such, they are acutely aware of the benefit of this simple device and the difference between high and low-quality models. This prolonged personal experience using transmitters combined with years of tech product reviews in categories like radar detectors, wireless speakers, top-rated multimeters, and more make them perfectly poised to pounce on these products and share their findings.

Analysis and Test Results

The FM transmitter market appears to be flat and simplistic; however, this is not the case. When listening to various musical genres transmitted through one device after another, it becomes clear that similar-looking and comparably priced machines perform at drastically different quality levels. That's where we can help you. Allow us to spend the money and time to buy all the leading models and test them. The following is a report of such an endeavor, and it lays out how we tested and, more importantly, which models performed well and why.

Sound Quality

As the name implies, the sound quality metric takes stock of the sound that comes out of the car stereo and how true it is to the original — what in music parlance is known as fidelity. While a high-quality transmitter won't make a low-quality car stereo sound better, it should nonetheless deliver clear, loud, static-free sound across a variety of audio genres. The Nulaxy models transmit high-fidelity (Hi-Fi) sound. However, the Nulaxy NX12 issues a slight buzzing when a device is being charged through one of its USB ports. This, unfortunately, is a common issue with the lower-ranked products we tested. The NX12 is unique in that it has superb sound output when not charging.

Our team's ears are well-trained to analyze sound quality. Part of this analytical skill is the experience to sort out the aspects that are lacking when the quality is low. To be honest, when using a run-of-the-mill car stereo, this isn't that tall of an order. We want little to no background static, hum, or buzz, as these noises dull the overall sound. We also want our bass to be felt rather than heard, and we want the subtleties of individual notes to come through. Fuzzy bass is a dead giveaway of low fidelity (Lo-Fi) transmission.

Ease of Use

No one wants to spend tons of time futzing with a little electronic device just to get a little music going to enrich their drive. We place a high value on the ease of operation of the transmitting device. The main issue with transmitters is changing the FM frequency. This action is necessary because when there is a station broadcasting on the selected frequency, it can overwhelm the transmitter's signal, thus reducing the sound quality. We favor units with frequency or channel buttons and a clear screen displaying the frequency being transmitted. Models that met this standard are the Nulaxy KM18 and Sumind. Unfortunately, most models require a two-step process to make adjustments to the frequency.

Of course, straightforward frequency adjustments are not our only concern. We make a holistic analysis of the user interface as well. Key points of interest are the placement of the input ports, the ease of fielding phone calls, and a confirmation of whether or not a Bluetooth connection has been established. When looking at all of these components collectively, the Nulaxy NX12 stands apart from the class for its overall ease of use.

Profile

Profile preference is specific to the needs of the user based on the location of the electrical socket in the vehicle as well as the display type and features (see below) that they desire. That said, we favored models like the Nulaxy NX12 and NX10 that are compact (more like a car charger in appearance) as we dislike a cluttered console and large, bright screens.

Having been clear about our bias, if you are interested in a model that does have a larger screen, or just a bit bigger user interface, there are several high-quality models that have larger profiles. The Nulaxy NX10 is a good option if you want to keep the profile to a minimum but still like to have a volume knob and track navigation buttons prominently displayed.

Features

Not surprisingly, several models that did poorly in the profile analysis did well in the features department. Machines like the Sumind with more features on offer typically require more real estate. These features include information such as Bluetooth connection, volume level, the radio frequency being transmitted, and the name of the connected device, as well as hardware ports such as Quick Charge USB, micro SD, and AUX.

The features metric also looks at the user interface. Here, we take note of the array of buttons and knobs controlling radio frequency, volume, and track navigation. As a testament to Nulaxy's thoughtful designs, the NX12 excels in both the profile and features metrics. Our hat is off to this transmitter as it boasts 3 USB ports, volume/phone call receive knob/button, frequency display, and a built-in microphone while maintaining a profile similar to a simple USB charger.

Conclusion

This comprehensive review of FM transmitters covers every aspect of design and functionality. We tested these products side-by-side for sound quality, ease of use, profile, as well as cataloging their features. The results of this analysis are organized to allow one to quickly and accurately parse the models that fit their needs and wants. With that, here's to getting crystal-clear audio without having to dish out hundreds of greenbacks for an unnecessary car stereo.