Test the following steps:

1. Turn off the headphones and leave them off for a few minutes.
2. Delete NERO-TX in from the phone's bluetooth list.
3. Place both headphones in the box and wait 2 minutes (make sure both headphones LED lights)
4. Start searching Bluetooth units on the phone.
5. Remove both headphones from the box at the same time, make sure that both headphones are flashing.
6. Choose NERO-TX from the phone's bluetooth list. Make sure there is only a NERO-TX in the list.

You can also test this:

1. Delete the headphone in all connected bluetooth lists.
2. Turn off both headphones through the button on the headphone.
3. Hold the buttons of both headphones until the lamps of the headphones blinks (and say "connecting")
4. Double -click both buttons at the same time.
5. Place both headphones in the box, and then reconnect them again.

* Always use the latest version of software/operating systems (Android/iOS) in transmitting device as this reduces the risk of bugs.

If it still would not work after testing both of these variants, please send an email to support@soundbysweden.se and we will help you further from there.

Yes you can use only one headphones at a time if you want. The headphone that is not used may be placed in the charging box in the meantime. It also does not matter which of the headphones you use (right "R" or left "L") as both headphones connect separately to the phone.

If there would be two different NERO-TX PRO showing in the transmitting device’s Bluetooth list, this means that the earphone only works as a mono (ie right and left eaprhone doesn’t sync with eachother).

To get the earphone to work as a stereo, you need to do a reset like following:

1. Erase the earphone from all conncected Bluetooth lists.
2. Turn of both earphones by the button on the earphone.
3. Hold in both earphones buttons until the LED lights are flashing and says “connecting”.
4. Double click on the both buttons at the same time.
5. Put down the earphones in the case and wait two minutes.

When you have followed these steps, you need to connect the earphone again like this:

1. Start the search for Bluetooth units in the phones Bluetooth list.
2. Take out both earphones from the case.
3. Connect/pair NERO-TX PRO in the phones Bluetooth list (only one NERO-TX PRO should be in the list).

If it still doesn’t work or if you need some more help could you contact support at support@soundbysweden.se and we will help you from there.

Unfortunately, our headphones do not support multipoint, so you can only be connected to one unit at a time.

1. Activate bluetooth on sending device.
2. Press centre button on remote control until LED is lit and voice declares “power on”. When
   diode starts flashing blue and red, it searches for device to pair.
3. When NiTRO-X appears in the list of available bluetooth devices, click it and the earphones
   starts pairing with desired device. The sending device will acknowledge pairing when done.

1. Delete the earphone from connected bluetooth device.
2. Turn off connected Bluetooth device for 3 minutes.
3. Turn off the headphones on the headphone button.
4. Press/hold both headphone buttons at the same time until the headphone LED flashes.
5. Double-click both headphone buttons at the same time.
6. Place the headphones in the charging box an wait two minutes.
7. Re-pair the headset to the Bluetooth device.

Watch video showing the full reset here!

The easiest way is via the app:

1. Tap Settings (the gear icon in the top right corner)

2. Tap “Factory reset”

3. Tap “Confirm”

If you don’t want to do it via the app, you can also do it manually:

1. Delete the earbuds from the connected Bluetooth device.
2. Turn off the connected Bluetooth device for 3 minutes.
3. Turn off the earbuds using the earbud button.
4. Press/hold both earbud buttons at the same time until a melody plays from the earbuds.
5. Place the earbuds in the charging case and wait 2 minutes.
6. Pair the earbuds again with the Bluetooth device.

See a video showing the full reset process here!

1. Delete the earphone from connected bluetooth device.
2. Turn off connected Bluetooth device for 3 minutes.
3. Turn off the headphones on the headphone button.
4. Press/hold both headphone buttons at the same time until a melody comes from the headphone.
5. Place the headphones in the charging box and wait two minutes.
6. Re-pair the headset to the Bluetooth device.

Watch video showing the full reset here!

To reset ZERO-TX:

1. In shutdown state, press the multi-function buttons for 10 seconds at the same time
2. When the red and white lights of both eras are steady on and off the headset will be shut down
3. Then put the to earphones in the charging case to activate
4. Take the earphones out, now shoud the auxiliary headphone lamp be off and they enters the “pairing state”.

Watch video showing the full reset here!

If this didn’t helped you with your problem, send an email to support@soundbysweden.se and where you describe your problem and that you have tested this reset and we will help you from there.

• Check that the charging box is not discharged. It should be charged with the supplied original cable to function optimally (other cables may cause conflicts in charging). When the box is charging, an LED light flashes white, which then changes to a solid white light when it is fully charged. If the light does not flash, the box is not charging.
• When the headphones are being charged from the box, the LED on the headphones lights up, if it flashes instead, the box has no contact with the headphones. Check that the gold pins in the box and the gold poles are not dirty or oxidized. If they need to be cleaned, the tip is recommended on a cotton swab or soft brush.
• Also, make sure you’ve removed the yellow tape around the pins in the box when it’s new, before you start charging for the first time.
• Avoid charging the box with a PD charger (fast charger), as many PD chargers are not compatible with the box.
• If the headphone battery is completely discharged, sometimes the battery may need extra power by connecting the charger to the box and placing the headphones in the box.

If you still have problems with loading after this, send an email to support@soundbysweden.se where you explain the problem and that you tested this and possibly then what the results were.

• In order for the earphones to charge in the box, is it required that there is contact between the gold pins in the box and the gold poles in the earphone. You will notice if they have contact if the earphones light up read when you put them in the box. If they don’t make sure that the pins and poles are clean. If they need to be cleaned, the top of a cotton swab or soft brush is recommended. Also make sure that you have removed the yellow tape that is around the pins in the box when it is new, before you start charging for the first time.
• It may also be because the charging box is discharged. The charging box is charged by connecting the supplied cable to the charging box’s USB-C input. When the box is charged, one of the four LEDs on the front should flash, which of them flashes depends on what percentage it has because each light indicates 25%. So the box is fully charged when all the lights are on with a steady light.
• If you notice that the charging box isn’t charging, there is most likely a problem with the cable. If you have the opportunity to test with another USB-C cable, please do, so you can see if it charges with another cable. Otherwise you can send an email to support@soundbysweden.se and we will help you from there.

In order to get the best out of the sound experience, it is important that you have the right size of the cushions and that they sit correctly in the ears. So test all the supplied pillows to find the ones that suits you the best. When inserting the earphone, start with the earphone facing down and then turn it 90 degrees to the correct position.

PD = Power Delivery and is available in USB-C fast chargers from 15 up to 100W. Unfortunately, NiTRO-X cannot receive a charge if a charger has this chip in itself, because the electronics in the headphone will then end up in conflict.

Note! We also do not recommend using these chargers on our other headphones, as they can be damaged by charging with chargers with this chip.

If the battery in the charging case isn’t charged, then the earphone will not turn off automatically when you put them in the case. The earphones LED should light up with a steady light to indicate that it is in contact with the box and then switches itself off. If the LED on the earphones flashes, it doesn’t have contact with the box and does not switch itself off.

So, try to charge the case and then try again! If it still wouldn’t work, send an email to support@soundbysweden.se and we will help you from there.

This is most likely due to dirt/earwax inside the grid. Carefully clean the earphone grid using a soft brush, e.g. tooth brush. If some sort of solvent is required, use hydrogen peroxide (N.B. max 3%) on a cotton swab and gently apply on the grid. Let it work for approximately 30 seconds and try brushing again. Do not apply excessive solvent, it may flow through the grid onto the driver, dissolve and irreparably destroy the driver cone.

If the above measures do not restore sound quality, we recommend that the driver grid is removed*. N.B. this way requires certain levels of skills and practice from working with tiny parts. The grid is fixed with an adhesive compound, possible to reattach. Use a thin needle or similar to lift the grid out, gently brush it clean and reattach it by gently pressing it back in original position.

*The later NiTRO models offer threaded grid assy, possible hust to unscrew from the ear capsule. The grid may be cleaned with just soap and luke warm water. Make sure the grid assy is dry before reassemble as water may irreparably destroy the driver.

If you think the sound is too low while using NERO USB-C, it may be that the phone (android devices) has automatically set a sound limit for the headphones. You can change this in your phone’s settings: Open settings and tap “audio and functions”, then look for “audio effects” and check if the “headphone sound limit when playing” setting is off, otherwise turn it off.

If it is already turned off or if it didn’t help to turn it off but the sound is still low, email us at support@soundbysweden.se and we will help you from there!

If you experience poor microphone sound during calls, please try this.

1. Turn off the phone for 3 min
2. Restart the phone and delete device (model name) in the list of connected Bluetooth devices.
3. Re-pair the headset with the phone.
4. Try calling via wifi call or through app e.g. Skype, Whatsapp etc. to ensure that it is not a matter of poor mobile coverage. OBS Zoom, Teams etc. have a number of bugs – go into settings – lower the quality of audio/image transmission.
5. Try using only one headphone at a time and see if there is a hardware error on, for example, the microphones on the right or left side.

If you still have problems after this, contact support at support@soundbysweden.se, also mention that you tested this.

If you have a phone with a 3.5mm port then the microphone with NERO does not work to the USB-C port, as it becomes like a blockage because the microphone on those units should actually come through the 3.5mm port. So if you use Nero-USB on a device that also has a 3.5mm port then you will only be able to use the headphones for music listening and not as a microphone during conversation.

On some phones you can make an update that makes this work anyway, here is a good video showing how to do with a Samsung phone: https://www.youtube.com/watch?v=no15gU4KX74

Samsung that works with calls and music: A53/A33/M53/S22 ULTRA/S22+/S21/S21+/S21 ULTRA/S21 FE/S20 FE/S20/S20 ULTRA/S20+/Note 20 Ultra/Note 20/Z FOLD4 3/ Z Flip/ Fold 5/ Filp5

Samsung Galaxy A32 works only for music playback.

If you have an Android phone, this is usually due to your device changing the audio codec to something that the earphone does not support. It should help if you change the audio codec to SBC or AAC. This is done in different ways depending on what device you use, but it should be possible to do it in your phone’s settings. If you can’t find it, try googling and you should probably get a guide you can follow.

If you need more help, you can always contact us via email at support@soundbysweden.se and we will help you from there!

If you feel that the sound is hacking from time to time, it is probably due to the signal between the headphone and the transmitting device in some way. There may also be surrounding factors such as household appliances, power lines or other wireless units that interfere with the signal. Also note that the bluetooth signal between the units becomes weaker in an outdoor environment compared to indoors.

The range of most Bluetooth devices is about 10m. However, optimal reach for this type of signal transfer is shorter than that. If you feel that the sound is chopping, you can try moving the devices closer together. For example, if you have the phone in the right back pocket, try to move it to the left front pocket so that the signal between the phone and the hearing will be the shortest possible as the headphone Bluetooth antenna is located in the remote control. You can also try restarting the headphone, restoring the pair with the transmitting device and then again pairing the headset with the transmitter unit.

iOS devices show the headphones battery level using a battery symbol in the display. The symbol is located next to the unit's own battery symbol.

For Android devices you need to go in through Settings and Connected units To find out the headphone's battery level. You also download any of the apps Bluetooth Battery Indicator or Bluetooth headset battery in the Google Play Store, to easily monitor the level.

When the headphones' battery level comes down to 10%, you hear a voice in the hearing say "Battery low" and it will then be time to charge the headphones.

• Make sure the slider (switch) on the back of the remote control is in the correct position for the operating system that your device uses.
Location 1 - Android and Windows
Mode 2 - iOS (Apple)

• Make sure the 3.5mm contact is properly pressed into the device so that it does not slip. Check this especially if you have a mobile shell on your smartphone as this may be in the way for the contact to be fully pressed.

• Verify that your smartphone is compatible with the remote control. 

This is very likely that you have not found the right size of the headphone pads. The package contains earphone cushions of different sizes and materials. Try you until you find a dense and comfortable fit for best sound experience. Also, ensure that you insert the headline properly. Start with the headset downwards and then turn it 90 degrees to the correct position.

This is a well-known phenomenon that can occur when inserting an in-ear headphones into the ear canal and it is usually referred to as "drives flex". What happens is that the overpressure that is formed when pressing in the headset is pressed past the speaker element so that this can be fluctuated which can cause a snapping/clicking metallic sound. This is not something that damages neither hearing nor headphones and is perfectly normal as you have been given a close fitting of the hearing in the ear canal.

You should not use a different charging cable than the one that follows in the package. The accompanying cable has a built -in overload protection and therefore cannot be replaced with a "standard cable". If you are using another cable, you risk destroying the headphones as the current can be too high.

If losing away or would have the cable, you can order new here.

You can find each headphone model's manual at the bottom of the respective product page.

If you were to lose some such as charging case or charging cable so it is possible to order directly here. Should there be anything else you have lost that you will not find on this page so send an email to support@soundbysweden.se with what you missand we will see if it can be solved.

Note! Since each headphone pair has a common unique ID, it is not possible to connect a new headphones to these, and therefore unfortunately it is not possible to order only one headphone in case you have lost one of them.

The app is available for download on the App Store™ and Google Play™ under the name SUPRA Audio©.

The app is compatible with all NERO-TX2 and NERO-TX PRO 2nd Generation. It is also backwards compatible and works with the previous model NERO-TX PRO; in that case, you may need to update the earbuds through the app if you have an Android device, or via the PC tool below. See the next tab for the update.

1. Click Settings (the gear icon in the top right corner)

2. Click “Upgrade software”

3. Click “Upgrade now” (here you can also see which version you have and if a newer one is available)

You should always be able to do it this way via Android; via iOS you may need to update via PC the first time. See below.

-

PC tool for software update:

1. Pair your NERO-TX PRO with your PC via Bluetooth. Make sure to remove any other NERO-TX PRO devices that have previously been paired with the computer.

2. Download the PC tool here

3. Open the file bt_upgrader.exe by double-clicking it.

4. Click “Search for NERO-TX PRO” (you’ll see an icon with headphones). The program will now start searching...

5. When SUPRA Audio Tool finds your device, the message will appear: Device found: 1 XXXXXXXXXXXX (this is the device’s MAC address).

6. Click “Press to update” (you’ll see a PC icon). You will see yellow text: Updating... and a percentage progress indicator.

7. When it reaches 100%, the message “Upgrade successful” will appear. Then wait about 20 seconds. NERO-TX PRO will restart automatically to complete the update.

8. To avoid confusion with the NERO-TX PRO address code, only one upgrade is supported at a time. Restart the app if you need another upgrade.

9. When NERO-TX PRO starts again, the update is complete.

Meaning of error messages if the upgrade fails:
1 - Failed to load the firmware (.bin) file
2 - Failed to connect to the Bluetooth earphones
3 - Failed to retrieve the version of the Bluetooth earphones
4 - The upgrade process for the Bluetooth earphones failed
10 - The Bluetooth earphones already have a newer version – no upgrade needed

This can be done on both NERO-TX2 and NERO-TX PRO through the app. Do this as follows:

1. Open the app

2. Click on Settings (the gear symbol in the top right corner)

3. Click on "Factory reset"

4. Press "Confirm"

1. Open the SUPRA Audio app
2. Make sure your earbuds are connected via Bluetooth
3. Go to the feature usually called:
4. “Find my earbuds” / “Find my device”
There you can:
📍 See the position on a map (GPS)
🔊 Play a sound in the earbuds to find them nearby

If you’re not connected, the app lets you see your last known location. Below we show how to do this on Android and iOS.

Android:

1. Open the app
2. In the list under "My devices", tap the name of the earphones
3. The app will automatically show the last location where the earphones were active.

iOS:

1. Open the app
2. In the list under "My devices", swipe left on the name of the earphones and tap the red field that appears.
3. The app will then automatically show the last location where the earphones were active.