1: Get noise/humming when turn the BOX X3 on?

• Please know that when no inputs connected to BOX X3, the default input way is MM input mode, in this mode, the gain of the amplify is much large then other input modes, so it’s normal that will have some humming sound when no sound pass through.
• Please unplug all the inputs from the BOX X3, then turn it on to check if the noise still or not.
• If the noise disappear, the noise may from the the audio source or audio cable, please exchange the audio source and the audio cable to try again.
• If the noise still, the noise may from BOX X3 or amplifier/speakers:
• Please exchange the audio cables and amplifier(powered speakers) to have a try and make sure that the noise is from which devices.
• Please volume down the “Treble” volume on the BOX X3 to check if the noise volume follows or not.
• Please make sure all the cables completely pushed into the device, incompletely connection will cause this issue.
• Please make sure that your turntable is MM output and also make sure that it is phono output, some turntables built-in phono preamplifier, so it should connect the 3.5mm AUX input on the BOX X3 not the phono input. Also make sure the grounding wire is connnected well with the BOX X3, please reconnect it to have a try.
• Please keep this device away from other electronic devices, like the FM radio or WIFI router.
• Please make sure the tubes is completely pushed into the socket, incompletely connection will cause this issue.
• Please reconnect the power adapter to the BOX X3 to try again.
Note: • If the noise still, please contact us via email at support@fosiaudio.com.
• BOX X3 is a preamplifier, not a power amplifier, can not be connected with passive speakers directly.

2. All cables are connected, but there is no audio output?

• Please check if your audio source, BOX X3, amplifier or powered speakers all are turned on and in working mode.
• Please check if the music in your audio source is paused.
• Please make sure that you are chose the correct input mode of the BOX X3, if the 3.5mm AUX input plug in, the MM input mode will be interrupted, and if the Bluetooth paired, the 3.5mm AUX input and the MM input will be interrupted, at this time if you want to use the line input, you need to disconnect the Bluetooth connection first. (if the LED light stay on RED,means the BOX X3 is in line in mode, if it stay on BLUE, means the BOX X3 is in Bluetooth mode)
– If the indicator light on the BOX X3 does not stay on, try another power supply(Any DC12V power adapter can work with BOX X3, you can use the power adapter of WIFI router or camera) that is suitable for the BOX X3. If the indicator light on the BOX X3 is on after replacing the appropriate power adapter, it means that the power adapter is probably broken, please contact us to replace the power adapter; if the indicator light on the BOX X3 is still not on after replacing the appropriate power adapter, it means that the BOX X3 is probably broken, please contact us to replace the BOX X3.
Note: Make sure that all the cables are completely pushed into the device.

3. My Bluetooth device cannot pair with BOX X3?

• Make sure that BOX X3 is powered on.
• Make sure that BOX X3 is not paired with other devices.
• Make sure that the distance between your device and BOX X3 is not too long, close your device to BOX X3 to have a try.
• Make sure there are no obstacles between your device and BOX X3, obstacles will affect the Bluetooth operation distance.
• Please try to change another Bluetooth audio source to test.
• Please reconnect the power supply to the BOX X3, and move the BOX X3 to your another room to have a try.
• Restart the BOX X3 and then try to connect again, try to use another brand of mobile phone.

4. Why Bluetooth is intermittent?

• Use another Bluetooth device to have a try.
• Ensure that there is no interference from other electronic equipment between the BOX X3 and the audio source.
• Put your device close to the BOX X3.
• Replug the power adapter.

5. How to distinguish Power Switch and Volume Control?

• Power switch means turn the power switch knob clockwise for one time to power on the BOX X3. Adjusting the volume means turning the volume control knob clockwise to adjust the volume.

6. How do you switch between inputs?

• The BOX X3 supports three inputs: MM turntable input, 3.5mm AUX Input and Bluetooth Input. The priority of switching between the three inputs: Bluetooth input >3.5MM AUX Input >MM Turntable input.

7. Can I connect a headset and the active speakers to the BOX X3 3.5mm AUX input simultaneously?

• No, the BOX X3 is designed with a 3.5 MM AUX input, not the 3.5MM AUX headphone output. But you can connect to the powered/active speakers from the RCA output connectors.
Note: BOX X3 is a preamplifier, if you want to connect it to passive speakers, you need a power amplifier.

8. My turntable doesn’t have a ground wire connection. Does this need a ground wire hooked up for it to be able to work?

• No, it does not need a ground wire to operate. However, if your turntable has any ground loop, it will be piped and amplified through the BOX X3.

9. How to attach ground wire?

• There is a post to attach the ground wire.

10. Is the gain enough to support MC cartridge?

• No. It is for MM cartridge.

11. My turntable has a selectable built-in phono preamp or switch to the line. Can I still use this instead of my built-in pre-amp?

• Yes, deselect the preamp on your turntable.

12. Can I hook the BOX X3 to the power amplifier for my system?

• Yes. You can connect the BOX X3 to the power amplifier through the RCA output.

13. Can this work with my turntable and headphones?

• No, it’s not design for headphones, and the 3.5mm AUX connector on the front panel of the amplifier is input, not output.

14. Can I directly connect this phono preamp to the speakers?

• If your speakers are powered speakers, you can directly connect this preamp to the speakers. But you need to add an amplifier or receiver to the passive speakers.

15. What equalization is incorporated in this preamp?

• RIAA equalization

16. Can you hook a subwoofer to this unit?

• Yes, if your subwoofer is powered, you can connect the BOX X3 directly to the subwoofer, but you need add a sub amplifier between the BOX X3 and the subwoofer if your subwoofer is passive subwoofer.

17.Which vacuum tube can be replaced to the BOX X3?

• If necessary, tubes below are substituttions: 6K4/6J1/6J4/GE5654/6AK5/66*In vacuum tubes, etc. You can replace the vacuum tubes to DIY your stereo system.

18. Sound quality is not good?

• Make sure all the cables are fully connected.
• Adjust the treble and bass of the BOX X3 to achieve the right tone.
• Please try to change the sound source and cables to test.

19. Can it be left on all the time?

• The BOX X3 is designed with a power switch. It can stay connected safely without power consumption all the time, you only need to turn off the power switch on the BOX X3.

20. Why the BOX X3 came with a broken vacuum tube?

• Due to long-distance transportation, the vacuum tube may be damaged during transportation. If you find that the vacuum tube is damaged or other problems, please contact Fosi Audio after-sales email immediately, and we will replace the vacuum tube for you.

Any problems please leave a message to the customer support email address: support@fosiaudio.com