The Fretlight Learning System utilizes 132 LED’s, which naturally produce slight electronic noise that, if improperly connected with your computer and amp, could be heard through your guitar amp. Any proper musical setup should ensure proper grounding. The following list of DOs, DON'Ts and Cautions will help you ensure a good-grounded signal and clean sound with your Fretlight Guitar:
DOs - When using a power cord with your computer, make sure the power supply has a grounded, 3-prong, plug. Most newer computers (2002 - Present) come standard with grounded power supplies. Make sure that the Fretlight USB cable is plugged into a root USB hub on your computer. That is likely the USB ports on the BACK of a desktop - the front ones most likely NOT root USB hubs, merely duplicates. Make sure that you are plugging into a wall outlet that is grounded, in other words, has 3 prongs. Only use your bridge pickup while running the lights. Use a clean channel at a moderate volume. If you are using a laptop, you should use it without connecting a power supply, thereby running it off its internal battery.
DON'Ts - Do not use a two-prong plug or a 3-to-2 adaptor plug. Do not use a two-pronged wall outlet. Only use 3-prong, grounded, wall outlets. Do not use an external USB hub - the Fretlight must be connected directly to the root USB hub of your computer. Do not use the middle or neck pickups or any effects while running the lights.
CAUTIONS - Try not to use power strips or extension cords, as they WILL introduce extra noise into the system. For best results, connect your system as listed above. Make sure that you are using a shielded guitar cable. There is a difference when it comes to extraneous noise introduced into the system - use a good cable, we recommend using a name-brand cable.
LAPTOPS - If you are using a laptop its power supply can introduce a ton of noise even if you follow all of the above instructions. If that is the case and you absolutely need to run it while plugged in rather than the battery, you will need to either use a hum filtering device, like the following example, or upgrade your computer's power supply to a double insulated two pin power adapter, or possibly use both.
Hum filtering device:
Check out this video to see this issue in effect outside of the Fretlight system and how to resolve it using those two suggested methods.