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Lifewire / Benjamin Zeman
Quick Charge 3.0 and 5V/2.4A USB charging ports
Large display and buttons
Clear audio with low noise
Auxiliary port input didn’t work
Viewing angle makes it hard to see
Gooseneck hose is not very flexible
Does not fit well in some cars
The Sumind Bluetooth FM Transmitter (Upgraded Version) is a popular device that stands out from its competitors. We found it works well for Bluetooth audio and hands free calling, but if you need an auxiliary port you may want to keep shopping.
The Upgraded Sumind Bluetooth FM Transmitter is a larger Bluetooth device that works through your car’s existing stereo system. You can connect nearly any Bluetooth-enabled device and enjoy your music or hands-free calling. We investigated Sumind’s interesting design, usability, audio quality, and the special features that make it stand out from the competition.
The Sumind Bluetooth Car FM Transmitter has two main parts connected with a flexible gooseneck. The part that plugs into a car’s 12V power outlet has both an intelligent 5V/2.4 USB charging port and a QC3.0 charging port. At the tip of the side that plugs into your car is an extended removable piece with a replaceable fuse. It’s not clear whether that additional piece was at fault, but we found the device more difficult to plug in than others we tested.
On the opposite side of the gooseneck is the device’s main body. On the front is a large 1.7 inch LCD screen that displays information bright and clear but only at limited viewing angles. Sumind advertises that the gooseneck can be rotated 270 degrees but we found that when we tried to angle the display towards us in the driver's seat, the gooseneck wouldn’t stay in position. Instead it would snapback, leading us to believe that unless the gooseneck needs to be “broken in” with a little more movement there’s closer to 180 degrees of rotation.
The fact that the primary input function of the aux port is so crippled is a significant downside, and if you’re mainly looking to connect a device via aux a likely dealbreaker.
There’s a large multifunction button and volume knob under the display with a ring around it that lights up when the device is powered on. On the left side are + and - buttons to adjust the radio frequency channel and on the right are next/last buttons to navigate songs. The buttons are fairly large and easy to use.
On the left side of the body is a TF slot so you can play audio files from a MicroSD card. On the right is a 3.5mm auxiliary jack that is advertised as both an input and an output (more on that later). Since the body is on a flexible gooseneck, it’s easy to get to both the TF slot and the aux jack. With the large buttons and display, the Sumind transmitter is designed to be very user friendly.
We tested this transmitter in a 2018 Toyota RAV4, which has two 12V auxiliary power outlets under the dash. Getting the Sumind transmitter into a position we could see from the driver’s seat was impossible. Although the screen is bright and easy to read from straight on, the viewing angles are poor and even with the amount of rotation the gooseneck allowed we couldn’t get it pointed straight at us.
The transmitter plugged right into our car’s 12V power outlet and we easily paired it to our phone over Bluetooth. We matched an empty FM radio frequency on our radio to an FM frequency on the device and audio worked right away. Listening to music and taking phone calls was easy and intuitive.
Using the TF card slot is as simple as putting in a card that has audio files in a supported format. The next/last buttons on the right are used to navigate through your songs. Switching between Bluetooth and charging mode is done by holding the next song button for five seconds. Overall setup was a breeze.
We were impressed with the Sumind Bluetooth Car FM Transmitter’s clear, low-noise audio. The BT70B has good noise- and interference-reduction technology and it’s evident in the high-quality audio. Audio is streamed over bluetooth version 4.2 and the TF slot supports FAT formatted MicroSD cards up to 32GB with MP3 or WMA audio files.
The BT70B has good noise- and interference-reduction technology and it’s evident in the high-quality audio.
Call quality was just as good as music and podcasts. The built-in microphone works well and hearing our buddy on the other end of a call wasn’t a problem. Overall we found the audio quality to be really solid, with the exception of one of Sumind’s special features—an aux jack that supports both input and output. Let’s take a closer look at this oddity.
The only truly unique difference between the Sumind Bluetooth Car FM Transmitter and many others like it is its unusual input/output combo jack. Honestly, the only reason we can think of for a 3.5mm aux jack that works both as an input and an output is that Sumind used jacks that just happened to have a chipset that also supports output.
It’s a novel feature, but the problem is that the aux input is plagued with issues. We thought at first the jack might be broken, but the aux output worked flawlessly. The included aux cable that came with the transmitter was really low quality and super noisy when we tested it with another transmitter, but when we used a known working aux cable it still didn’t work. Then we plugged the cable from the aux output of the transmitter into the aux input of our car. It was lower volume than any other audio but it worked.
Of course, the use cases for a 3.5mm output are extremely limited. The fact that the primary input function of the aux port is so crippled is a significant downside, and if you’re mainly looking to connect a device via aux a likely dealbreaker.
Sumind’s large display allows a large amount of information to be displayed, and the software handles it well. It does an excellent job of surfacing the most important information. There’s an icon showing whether or not Bluetooth is on, if a track is paused or playing, the volume level, the FM frequency, and what device the transmitter is connected to. Every software function worked great and we didn’t notice any lag or glitches.
The BT70B is an excellent current gen transmitter and an easy, inexpensive way to add Bluetooth functionality to your vehicle.
The Sumind BT70B transmitter averages around $26 and can sometimes be found for less with a little bargain hunting. It’s on the higher end of the Bluetooth transmitters we’ve tested but it packs all the features we want, except for a working auxiliary input. We often use a portable music player and an aux input is a must.
Sumind’s offering is otherwise a solid value. It’s got everything else you need and good audio quality to boot. Couple that with the large, user-friendly buttons and you have a winner.
The Nulaxy KM18 is an older gen model with all the same functionality as the Sumind BT70B and can usually found between $17 and $20. If you’re looking to save a few dollars the Nulaxy could be a good bet.
It also has good audio quality with low noise, easy to use buttons, and an aux jack that works. However, the display is smaller and more difficult to see and like Sumind’s transmitter the gooseneck cable isn’t very flexible.
The KM18 is an older gen model from 2015 and has been a very popular option for years. Nulaxy also makes an upgraded KM18 Plus version. We think all three are good options that justify their price tag. If we didn’t need a working aux input we’d probably choose the Sumind, especially because we prefer the shape of the chassis and the convenience of two USB charging ports.
The Sumind BT70B Bluetooth FM Transmitter is a good buy with some quality control issues.
We like Sumind’s shape and the large, easy-to-use buttons and dial. It has the largest and best looking display we saw in this round of testing and audio sounded great from any source. Outside of our issues with the aux port, the BT70B is an excellent current gen transmitter and an easy, inexpensive way to add Bluetooth functionality to your vehicle.
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