The diagram below shows the note layout for a standard, diatonically tuned hammered dulcimer with 12 treble courses (Left hand side), and 12 bass courses. This is probably the most popular configuration over here in the UK, but bear in mind there are many others. E.g. in the US a 15/14 course layout is favoured. If you need further info on tuning layouts, most of the makers are only too willing to help out, or send us a specific query and we'll try to find the info for you.