i knew Bob Mize.  he wrote an article for foxfire detailing how to build a mtn dulcimer.  he once told me the fret board was "off"

maybe this could shed some light on this discussion.  at the time i was not aware of the different intonations used.  i did not

push him for an explanation.  he made beautiful instruments.

bo

Hi Noah - I'm a little late coming to this thread!  It looks like you have sorted out the issue.  On a lot of older dulcimers the 'trick' is to work out how the maker set up the instrument initially and for what tuning and what style of playing.  Sometimes nuts, bridges and string gauges have been altered and it can be a devil of a job to work out how to get an instrument playing well  

I found and read those articles and what they seems to be the case. The frets are flat to accommodate for a noter.

Just did a little digging and found out that many dulcimers from that era were set to play in DAA or CGG and with a noter.  The belief was that when a noter was used the tension on the strings would compensate for the flat ring.   You might check with John Huron at Noteworthy Instruments as he worked with Bob Mize...he can probably tell you  more about why the frets were set to sound flat at 7 and often times 1 than I can.  Since your question has got my curiosity up I'll keep looking around some of the back issues of DPN and see if I can figure it out.  I read a post a bit ago that said that every Mize dulcimer he ever played was flat on 1 and/or 7.

Update: I just found a thread on Everything Dulcimer that discusses this issue.........check out the posts under Robert Mize Authority?  From what I can discern the root note was tuned at the third fret with adjustments made for string gauge, bridge height and so on...........Robin Clark has written about this too.....when you figure it all out post what you have learned because old codgers like me are a little bit fuzzy on all this stuff.

Well that's good. I changed the strings to equidistant (still 1-5-5) and had fun with that, but the 3rd fret and 7th fret are just too flat for that. It is better playing noter drone.

Rather than Just Intonation, it could be fretted for Mean Tone.  John is right that none Equal Temprement dulcimers are often set up for  specific tuning that is usually not 1-5-8.

Noah, it could be fretted in another temperament other than the equal-temperament that most modern dulcimers have.  It could have been designed to play in one particular tuning, or to play only in the noter/drone style. There are discussions on this site regarding this issue.  By no means should you consider the fretting pattern a defect in building.  You may want to check into this here, or at Everything Dulcimer.  Best wishes in your research.

My grandpa on my mom's side owns an all cherry Mize dulcimer.  We moved their stuff up to tn over the weekend (they are moving up here later this week) and I have gotten to play this dulcimer.  The dulcimer's frets have a strange intonation I haven't come across before. They are greatly flat and the 7th fret is more flat than the others. What intonation is this and why did Mize tune it like this? Maybe it's Just, but I didn't think Just was this flat.