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FAQ – Frequently asked questions & answers

Only one earphone connects to the phone (applies to True Wireless models, e.g. NERO-TX)

1.Put both earphones back into the charging box, wait for the earphones LED to stop flashing and instead turn to solid white light. Then delete NERO-TX from the phone by going into the Bluetooth list and select Forget device alt. Cancel pairing.

2.Then pick up the left earphone (marked “L”) and pair it again with the phone. When the left side is connected, pick up the right earphone (marked “R”) and connect it likewise.

3.You can also turn the earphones off by holding down the button for a few seconds. When they are turned off, you hear the voice prompt “Power off”. Then press the button again for a few seconds until you hear the voice prompt “Power on”. Then put the earphones back into the charging box. The LED lights will then flash with white light. When they stop blinking and instead turn to solid white light, you can pick them up again and reconnect them with the phone.

* Always use latest version of software in your phone/transmitting device to reduce the risk of  software bugs.

The earphones do not connect to the phone (applies to True Wirless models, eg NERO-TX)

1.This may be because of low battery level in the earphones. Replace the earphones into the charging box (make sure the battery of the charger is charged). The LED lights up with a solid white light during the charging process and turns off when the earphones are fully charged. Then pick up the earphones and reconnect them to your phone. Connect the left “L” earphone first followed by the right “R”.

2.Make sure the earphones are in “ON” position. The earphones are switched on/off by holding down the button for a few seconds. You hear the voice prompt “Power on” when the earphone switches to “ON” mode.

The earphones are not charged in the charging box (applies to True Wirless models, eg NERO-TX)

1.This is probably because the battery in the box is discharged. Recharge the box by connecting the supplied charging cable to the Micro USB input of the charging box. The charging box LED flashes red during the charging process and turns red when the box is fully charged.

2.In order for the earphones to be charged in the box, there is a need for contact between the gold pins in the box and the gold poles on the earphone. Ensure that pins and poles are clean. If they need to be cleaned, use the top of a cotton swab or soft brush.

How to pair? E.g. NiTRO-X Wireless

  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.

Sound quality is deteriorating and/or level is decreasing.

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.

Sound is fragmentary and/or irregular

Probably the sound stream between the device and earphones is jammed or disrupted. It may
depend on normal household appliances, other wireless devices signals or the distance between
the earphones and device is too far or blocked.

The bluetooth reach is normally about 10 meters. Optimally it should be even closer, not to get
corrupt bit streams. Try to shorten the distance between earphones and playback device. If
problem remains, try re-starting the earphone and device, restore the paired devices and finally
try pairing them again. Always make sure that you have latest software update from the
manufacturer of your sending device.

Determine battery level on my wireless earphones?

iOS devices offer a battery level monitor symbol in the display next to the internal battery symbol
of the device.

Android devices offer a monitoring of the battery level if you check for “connected device” in
settings menu. There are also apps in Google Play Store like e.g. Bluetooth Battery Indicator or

Bluetooth Headset Battery to monitor battery level.
When battery level reaches 10% and dropping, the earphone voice synthesis speaks “battery low”.

Remote control malfunctions; e.g. adjusting volume, skip track, play/pause or answer incoming call.

• Check remote control rear switch position (apply to certain models) to fit desired device
Pos 1 – Android and Windows
Pos 2 – iOS (Apple)
• Check that possible earphone cable connector (3.5 mm plug) is properly seated, especially if
case, shell or cover is mounted
• Verify device compatibility.  Visa kompatibilitetstabell.

Poor bass sound

The most common reason for poor bass level is wrong size of ear tips. They act as a seal
enclosing the bass punch. If there is leakage, the resulting bass sound pressure inside the ear
become much lower.

Unfamiliar metallic click sound while mounting the earphones into the ear canal.

A phenomena deriving from the overpressure inside the ear while entering the earphone capsule
called “driver flex”. The pressure peak passes the driver cone with a click and is fully normal,
completely harmless to both hearing and earphone and is actually more of an acknowledgement
that now the fit is perfect with a very good and tight seal.

How to find a user’s manual?

Every model user’s manual is offered as a download link called “manual” found in the technical
specification section on Sound by Sweden webpage. You can also click on the links below.

Nero   |  Nero-X   |   Nitro   |   Nitro-X

I´ve lost the supplied charging cable. How to charge without original cable?

The cable for charging our earphones is a standard USB-A to Micro-USB. Cables with this
standard are available at almost any electronics retail store.

Can I use a different charging cable than the one supplied in the package?

You should not use a different charging cable than the one supplied in the package. The included cable has a built-in overload protection and therefore cannot be replaced with a “standard cable”. If you use another cable, you risk destroying the headphones because the voltage/amperage may be too high. If you lose or break your cable, contact our customer support at support@soundbysweden.se to order a new one.


Sound By Sweden AB
Org.nr 556771-3382