To customize a ringtone on your Marshall London:
(1) Connect the Marshall London to your computer as an MTP device
If using a Mac computer, you will need to download the Android File Transfer App found here, Marshall London Support Drivers . After installing the Android File Transfer App, it will be located in your Apps folder.
If using a PC, you may need to download the Windows driver here, Marshall London Support Drivers.
(2) Locate the song (that you want to set as the ringtone) on your computer and transfer (drag & drop) it to the ringtone folder in the Marshall London.
The ringtone folder will be found in the London's internal storage folder shown on your computer.
(3) On the Marshall London, enter settings.
> Sound & Notifications
> Phone Ringtone
> Locate the audio file that you loaded onto phone and set as the ring tone.