Nulaxy KM30 Bluetooth FM Transmitter Review

Do you have an older vehicle, but don’t have a way to connect your phone, tablet or other device to it to play music or receive calls? A Bluetooth FM transmitter may be just what you are looking for. In this review we are going to be looking at the Nulaxy KM30 and telling you are thoughts on it after using it for the past half a year or so.

Make sure you also check out our full guide to the best Bluetooth FM transmitters for a “round up” of multiple different options.

How Much Does the Nulaxy KM30 FM Transmitter Cost?

We purchased the KM30 for $23.99 on sale from $26.99. This is the same as it costs at the time of writing this article (around 6 months later), but be aware that prices do change. The $23.99 price point puts the Nulaxy KM30 squarely in the mid-high range when it comes to Bluetooth FM transmitters for cars. There are some more expensive options, but not many.


Below we have listed the specifications for the KM30 as per what was provided on the packaging:

Bluetooth Version5.0
Product Input 12 – 24V
USB Charger Output QC3.0 (total 18W)
Net Weight 61g
Dimensions84.8 x 40.9 x 112 mm (3.33 x 1.61 x 4.4 inches)
Manufacturer Sage Human Electronics International Co, Ltd
Screen1.8-inch colour
Frequency Range88.1 to 107.9 MHz
Transmission range 2m
Supported music formatsMP3, WMA, FLAC, and WAV

First Impressions (Packaging, etc,)

There really isn’t too much to discuss when it comes to the packaging side of things. The Nulaxy KM30 comes in a nice sturdy box with all the main features listed on the top and the specifications listed on the rear. Most of the packaging was carboard, but the transmitter was held in place by a plastic mould.

Along with the transmitter, the packaging contained an AUX cable, instructions and an extended 24 month warranty card (the normal manufacturer warranty is six months). As per the card, the registration for the warranty needs to be completed within seven days of purchase. We did not go through this process, so can’t comment on that.

The KM30 itself is on the larger end size wise when it comes to the FM transmitters we have tested. It features a 180 degree rotatable neck that allows you to reposition the transmitter so the screen can easily be read by the driver or the passenger.

In total there are six different buttons that allow you to change things like the channel/frequency, the song, bass level, and treble level. There is also a knob that gives you the ability to adjust the volume on the KM30 itself.

On the left side of the transmitter there are two USB ports; the orange one is the QC (Quick Charge) 3.0 port, while the other one can be used to play music off a USB flash drive. On the right side there is a Micro SD card reader, a feature that we don’t often see on Bluetooth FM transmitters for cars.

The transmitter is made from a matte black plastic material and overall it feels fairly sturdy (although quite lightweight). It doesn’t feel as high quality as something like the IMDEN C57, but at the end of the day it is just an FM transmitter and as long as it feels somewhat durable we are happy with it.


To get the KM30 going, plug the transmitter into the cigarette lighter socket of your vehicle. The KM30 will then turn on automatically and the LED display will show the FM frequency, volume level and some other information.

Once you have plugged the KM30 in, you then tune the radio to an unoccupied frequency from 88.1 to 107.9 Mhz (you should hear some white noise/static). Following this, the next step is to adjust the frequency on the KM30 to the same as the radio by using the “CH+” and “CH-“ buttons.

The final step is to pair the KM30 to your phone or Bluetooth capable device. Go into Bluetooth devices/settings and you should find the KM30. If you don’t, give it a second and see if it appears. Once it has, select the KM30 device and you should hear a sound that confirms the connection is successful. You can confirm this by looking at the screen. If it has successfully connected it will show your devices name (“iPhone” in our case) and if it hasn’t it will simply display “Bluetooth KM30” on the display.

We felt that the overall process was easy enough and the dedicated channel/frequency buttons were better than having to press and hold or do something else to change the frequency. The KM30 popped up immediately in our Bluetooth devices list and it is good to be able to visually confirm that it is indeed connected to our device.

One issue we have found after using the KM30 for a number of months is that after starting the vehicle, it can take quite a while for the transmitter to reconnect with our phone/device. Sometimes it can take a good minute or two before it remembers to connect, unless you manually disconnect the KM30 and reconnect in the Bluetooth devices list.


While we didn’t need the instructions to set up the Nulaxy KM30, we did give them a read. They are more extensive than pretty much any other transmitter we have tested and they cover five different languages; English, French, German, Spanish and Italian.

The instructions give and excellent rundown of all the features and how to use them, from things like answering a call, to activating Siri/Google Assistant, and changing the bass. Overall we were very happy with the instructions.

Sound Quality

Many Bluetooth FM transmitters get a bad rap for poor quality sound (justifiably so), but how does the Nulaxy KM30 perform?

In short, the sound quality is adequate, but very good for a Bluetooth FM transmitter. It is slightly muddy, so if you go in expecting the audio quality to be like that of a wired connection you will be disappointed.

Still, despite this the audio quality is good enough that the KM30 wound up being our daily driver over all the other FM transmitters we have tested. The only other FM transmitter we have tested that we feel has better sound quality is the Avantree CK310. However, this transmitter has far less features, requires a separate power connection (doesn’t plug straight into the cigarette lighter) and is more expensive.

The KM30 does have an AUX out, so if you find that you are getting a bit of unwanted noise you can plug it into your car’s AUX in socket (if it has one). We didn’t have a problem with the standard setup, but this does improve audio quality.

Bass and Treble Adjustments

One feature that the KM30 has over its competition is the ability to adjust the EQ via the “BASS” and “TRE” (treble) buttons. For example, if you press the “BASS” button, the transmitter will enter EQ mode and you can use the volume knob to increase or decrease the amount of bass.

While these sorts of features are often gimmicks on relatively cheap devices like an FM transmitter, the treble and bass controls on the KM30 do actually work. There isn’t a massive difference between max and minimum settings, but it is audible.

You can get much better control of the EQ settings via an app or program on your phone/device, but it is quite handy having some control on the transmitter itself. This feature certainly isn’t a must have, but it works better than we expected.

Playing Music

There are a couple of ways you can play music through the KM30. The first method is to stream music from your phone/device to the transmitter where it will play through your cars audio system. This is what most people will probably do, but you can also play music off a USB thumb drive or a microSD card.

To play music off a USB flash drive or microSD card, plug in the drive/card and long press the multifunction button (the volume knob). This will then take you to a screen where you can select the different folders on the drive or go straight into the play mode interface. Use the volume knob to select what you want to do and then press it to enter.

The play mode interface is a lot more limited than something you will find on the Spotify app for example, but it does let you do some things like repeat, repeat all, random play, etc.

It is important to note that the KM30 only supports MP3, WMA, FLAC, and WAV music formats, however, this should cover pretty much anything you have. Additionally, in the instructions Nulaxy states you can only use a drive/card up to 32gb, but they advertise it as being able to support up to 64gb. We didn’t manage to test if the higher storage amount works, but we can’t see why it wouldn’t.

To switch to the next song, press the dedicated forward button, while to go back to the previous song, press the back button. Pressing the multifunction button/volume knob will let you pause or play a song.

Overall, the controls are easy to use. We found that once we set the volume, bass, treble, etc. we haven’t really touched them sense. We set the volume to max on the KM30 and then just used the volume knob on our car to control the sound level. We did this because we found that if we switched back to the radio it could be quite loud (the KM30 reduces the sound level a bit).


Like pretty much all other FM transmitters on the market, the Nulaxy KM30 gives you the ability to take and receive calls through your vehicle’s sound system.

To answer a call you simply short press the Multifunction button and do so again to end the call. If you want to reject a call you long press the Multifunction button. If you are in the middle of a call but want to make it private (so it comes through your phone), simply long press the Multifunction button.

The call quality is much the same as the sound quality for playing music, so we had no problems with it. Once again it was a little bit muddy but perfectly usable for calls.

Siri and Google Assistant

While we are not big users of Siri or Google Assistant, you can use them with the KM30 by long pressing the forward button.


The main charging port on the KM30 is a QC (Quick Charge) 3.0 Fast Charging Port. This should theoretically allow you to charge a phone with a 3,500mAh to 4,500mAh battery to 80 percent in as little as 35 minutes when the battery is fully depleted. This QC 3.0 port puts it above many other FM transmitters on the market and is a really handy feature to have.

The second port is intended for USB flash drives, but it does provide some charge. Nulaxy does not state the amperage of the port, so we can’t give you exact figures. We would only use this port if you really need to charge two devices at once (and then you would probably be better of swapping them over when the first device is finished charging on the QC 3.0 port).


The Nulaxy KM30 is the best Bluetooth FM transmitter we have tested so far. It offers the best combination of features, sound quality and price. It has been our daily driver for the past six months and we can’t see our selves swapping to anything else. If you are looking for a Bluetooth FM transmitter, this is the one to get.

You can read a full comparison of some of the FM transmitters we have tested here.


  • Ben

    From his early days playing the original Gran Turismo and with his Hot Wheels car set, Ben has had a long interest in all things automotive. His first foray into the world of automotive journalism was way back in 2009 and since then he has only grown more interested in the industry. Ben also runs and heads up the video production side of Garage Dreams, focusing on small informative documentaries about some of the world's most legendary cars.

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21 thoughts on “Nulaxy KM30 Bluetooth FM Transmitter Review”

    • Press and hold the treble “TRE” button until device shuts off. To turn it back on do the same thing. In doing so you won’t have the problem of the transmitter not auto-connecting like they mentioned in the article.

  1. Bass and Treble Adjustments
    No one ever mentions the fact that these units also have a separate EQ function. Long press the (volume knob) and an EQ sub-menu shows up. There are 5 or 6 EQ modes to choose from, the bass and treble are on top of that sub EQ level then. (don’t be manly, not read the manual)

  2. When receiving calls does conversation go thru cars speaker system and how is volume of conversation adjusted? Via volume knob on car radio, volume +or- on phone or on the transmitter?

  3. How does it works with the folder structure in an SD card or USB Stick?

    If I have in the SD root several folders, one for each band, and inside each band folder, several folders for each album, can I go directly to a band folder, enter it, and then select between the band albums?

  4. Also it has a neat option, it displays your car’s Battery voltage on the main screen, you can see it decreasing if your car isn’t turned on, this comes in very handy for me as I have a weak battery and if I space it out and leave radio on without engine tuned on for little too long I end up stuck needing a jump start, so with this, I can monitor the voltage and it’ll start blinking when it drops below 12v

  5. Searching for a remedy of a “glitch” that discovered to my Bluetooth FM transmitter that is absolutely the same as Nulaxy Km-30 device but with anothe name felt on your excellent presentation.
    May I ask you if you have any findings as match as concern the SD or TF card reading ?
    Here is my situation. Have 4 different SD cards that are used to play my music.
    All cards are formatted FAT32 (a very old 2 Gb and another also old 4GB ).
    Recently bought another 2 pieces to store and play my music files. One 8 Gb micro SDHC-10 (speed up to 25 MB/s) and another Ultra 32 Gb micro SDHC UHS-I with speed (Up to 120 MB/s). As mentioned all formatted as FAT32. All are playing the Mp3 files excellently except the 32 Gb Ultra that it is recognized by the device finds the files but when start to play felt on a loop for 2 – 3 seconds trying to play for another 2 seconds and continued that fact infinitely. By that way no music are produced. In a contrary that 32 GB flash drive plays the same files without any issue.

    If you have experienced any of such “glitch” will be in fond of all of us to know that and to use lower speed SD cards, or my device has this issue and has to be replaced by the selling company.

    • Hi, thanks for commenting. We don’t sell these products (just review them) You can buy from Amazon by following the link in the article.


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