User Guide

minimum volume;
• Please make sure your audio source need a pre-amp or not;
8. Bluetooth can’t work
• Please unplug the power supply into the AC outlet, then re-plug it again to try again.
• Please change the Bluetooth device to try again.
• Please make sure that the amplifier is not paired with your other Bluetooth device.
• Please move your Bluetooth device close to the amplifier.
• Please check the BT and the AUX select is on BT position.
9. Hum
Adding a new component such as Fosi Audio amplifier can bring out hum or buzz that may not
have existed before. Your first assumption may be that something is wrong with the component
but this is generally caused by a “ground-loop” in your system. Consider these tips for possible
solutions:
• First try moving all components to the same electrical circuit or AC outlet.
• If the hum or buzz is still present, power off all gear and remove the mini-jack and/or RCA
audio cables to and from the amplifier.
• Turn the amplifier back on and check for hum. If the noise is still audible try plugging the
power cable into a different AC outlet.
• If the hum goes away while the audio cables are still disconnected, the noise is likely coming
from another component in your system. Connect each component back one at a time and the
one that causes the system to hum is likely the culprit.
• A common ground-loop source is from cable TV or satellite cables. If the hum or buzz
persists after trying the previous tips, disconnect the coaxial cable from your cable box, TV, or
DVR and if the hum goes away the cable is the cause. In this case you can get a ground-loop
isolator from your local electronics store. These are inexpensive and easy to connect inline with
your video cable.
• Sometimes something as simple as a portable heater or dehumidier will add noise into your
wall wiring that could be picked up by your audio gear. A dimmer switch on a halogen lamp, a
wireless internet router, or wireless phone near the amplifier, for example, could also all be
possible culprits.
The best overall solutions are to use an AC line filter, plug the unit into a different AC circuit, or
in the case of noise introduced by a wireless router, for example, move it further away from your
audio gear.