String Choice Workbook
Choosing the best set of strings for a musical instrument is always a complex matter. One way to simplify the task is to start with a string or strings which are working well now, and finding out their tension. Then, choosing a whole set of strings that are approximately the same tension is a good first choice.
You can use this worksheet to plug in the string sizes and pitches you are currently working with, to see if they are all at a similar tension when tuned to pitch. From there, you are better equipped to decide whether tuning your current strings to a different pitch gives you the desired timbre and voicing of your instrument.
Then use the spreadsheet to find the string sizes that will be at that tension when tuned as you want them. I've found this to be a reliable way to find the strings that give you the voicing you want. Choosing a set of string sizes that all operate at your instrument's best tension is highly likely to yield the instrument's best performance.
This is a new version of the worksheet. Notice particularly the "Calculate Diameter" box in the "Dulcimer Setups" worksheet. A fast way to see what new strings you need, if you are wanting a different set (but not as accurate as the individual worksheets, so always take the "Calculate Diameter" as a first guess. Then take those recommendations to one of the other working groups on the page, plug in the new diameters and see what results).
Shown above is a static image of the current state of the workbook. To explore the tool email me for a copy of the Excel workbook, or for some consulting. This is a collection of spreadsheets, including data on hammer dulcimer strings, contributed by Karl Mouck.