The Boss GT8 is a floor-based multi-effects and amp modelling processor for guitar. It features Roland's "Composite Object Sound Modeling" amp modelling technology. The GT8 includes 46 amp models and a variety of COSM-modelled effects. The unit also has "Solo Mode" and "Dynamic Sense," allowing you to change between amp models based on how hard you pick. The GT8 also includes a built-in tuner, expression pedal, amp loop and MIDI inputs and outputs.
Connect guitar to the input on the rear of the GT8. Connect the output of the GT8 to an amplifier. Connect headphones to the "Headphone" jack if desired. Lower all volumes. Apply power to the amplifier and the GT8. Raise the volume to a comfortable listening level using the "Output Level" knob on the back of the GT8 and the volume knob on your amplifier.
Select the device you are connecting the GT8 to by pressing the "Output Select" button. Turn the "Patch-Value" dial to select the type of device. Press "Exit" to return to the performance mode.
Select a preset which is similar to the sound you want using the "Bank" switches to navigate between banks and switches one through four. Press the "Manual" button to change the GT8 to Manual mode, allowing pedals one through four to turn on and off individual effects.
Edit a patch. Press the on-off button for the effects you want to enable or disable. Press the "Parameter" key repeatedly until the desired effect parameter appears in the display. Rotate the "Value" dial to change the parameter. Turn the "Preamp-Speaker" knobs to change the preamp settings. Press the "Write" key two times to save the patch to the current location.
Copy patches to locations in the order you intend to use them. Select a patch to move. Press the "Write" key once. Rotate the "Patch-Value" dial to move the patch to a desired user-patch location. Press "Write" again to store the patch to the location.
Change the connection order of effects. Press "FX Chain." Use the "Value" dial to a location where you'd like to insert an effect. Press the "On-Off" button for the effect you'd like to add. Press the "Write" key two times to save the order to a patch.
Use good quality cables and read all documentation.