I really do not understand...should be the easiest thing to do...but it isn't....please help
Hi Giuseppe,
Thank you for your message, please the link below, there is a video to show you how to activate the tuner
https://my.marshall.com/support/tutorials
Marshall Support
It´s easy. Hold Prefx and AMP button and press A1 button. Tuner is saved now. Press and Hold button A1 - you see your choosen preset, press it again and the tuner pops up with a string digit A E D G .. Tune your guitar, return to A1 by pressing the bank/ switch mode button two times. The tuner is automatically programmed by Marshall factory.