Thanks for putting this here Nate. 

I left out in the vid that I surely appreciate the tone/timber of the bigs they are something special.

Thank you @strumelia for the useful details and thank you to everyone else for all the input in general. This has all helped me a lot to get a better perspective on the what's and why's

Nate

I like what Stumelia and Dusty write here. Dulcimer players often do not seem to care about the change in timbre when they tune strings to a different pitches (and thus different tensions). My experience is that longer strings have a warmer tone, due to the variety of undertones, as well as a different set of transient dissonance (which affects brilliance).

And what Dusty says about the player's fretting technique is important, if one is playing chords. I see many people reaching for chords with thumb and pinky. If one does that too often the thumb is liable to suffer, as it is not really structured well for fretting, which requires more lateral pressure. The hand and its members just are not built well to sustained lateral pressure.

In advising my clients about scale length I ask them to consider whether they do much chordal playing, then find the place on one of their dulcimers at which they are comfortable with forming the most demanding chord without using the thumb. Then I advise that they need a scale at which such a chord can be achieved over the first three to five diatonic frets.

I mean like for several examples-

--If i was playing dulcimer in an oldtime fiddle jam session, they usually play in the keys of D, G, and A. I used to use my slightly shorter scale dulcimer for tuning up to key of D, and I'd keep my slightly longer scale dulcimer for tuning lower to the keys of G and A. Changing tunings too often or drastically can wear the strings and make them break faster. For example changing from a DAA tuning to DAd back and forth too often is something I try to avoid when jamming.
--When I'm at home and trying to sing with the dulcimer, the key of D is too high for me, so I might go to a lower key for that as long as i don't have to consider what keys others might need to play instruments in.
--If I'm playing a lonesome/sad tune it would usually call for either an aeolian or a dorian type of tuning, as opposed to a 'happy' sounding typical DAA or CGG ionian-friendly tuning.

I've made lots of long blog posts on my noter blog about how I myself deal with all these things, I can't really summarize or condense them here. Your question is pretty broad and covers a lot of ground. My blog does have an index to sort posts by subject matter, so maybe you can find something helpful there in addition to other folks' fine suggestions here.  :)

Nate

As a general rule, we might assume that VSL independent of other variables has some effect on volume and sustain, but the other aspects of design weigh heavier, I'm sure.  It was probably once the case that baritones in general had longer VSLs, but there are several luthiers now (New Harmony, Folkcraft . . . ) making baritones with a 25" VSL.  (After all, if Taylor can offer their GS Mini as an acoustic bass, then anything is possible.)

As a chord player, I find shorter VSLs much more comfortable.  Yes, I can stretch to that 1-2-4 A chord on a dulcimer with a 28" VSL, but it feels like I'm stretching.  That same chord on a dulcimer with a 25" VSL is just plain comfortable.

There are a few luthiers (Folkcraft, Terry McCafferty) who use the same design and make dulcimers with varying VSLs by moving the placement of the bridge (McSpadden moves the nut for the same purpose, but I'm a little skeptical of that approach).  You might ask them what they've noticed about the effect of VSL on the volume, sustain, and tone.  I have a 25" McCafferty, and I suspect that had I opted for the 25.8" or 27" model, I would have a wee bit more sustain, but I doubt the tone and volume would change much.

Scale length is always a matter of personal preference. Three of my guitars have vsls of 25.5 inches and of course all those fret boards are chromatic. My banjos are 26.25 inch vsl. The length I prefer for the dulcimer at vsl of 27 although I have some shorter than that and longer than that. As to strings, I don't buy dulcimer string sets. I buy strings in bulk for the gauges I prefer, both ball and loop end strings. I also make custom strings from spools of piano wire. Prepackaged dulcimer strings are just plain steel strings and wound strings packaged for dulcimer builders (Folkcraft andMcSpadden, etc.) by string manufacturers who make strings for guitars, banjos, mandolins, balalaikas, hammered dulcimers, etc. So, I don't think there is really any benefit to a longer VSL. If you like the sound and feel of a longer VSL, go for it. If not, choose one that appeals to you.

Ken

"The dulcimer sings a sweet song.

To me, scale length has been hugely important dependent on what tunings and keys I want to play in. If you're a singer it is critical. This matters less when you plan to play by yourself, but becomes super important if you plan to play with other people, especially if the other folks are not only playing dulcimers.

My dulcimers and banjos have a certain narrow range of scale lengths because I have always played them with other people on other instruments, or have sung with them. On the other hand, my custom langspil I was able to have made in a longer scale to tune a key or two lower, because i knew i would only be playing it by myself and wanted a lower key 'mournful' sounding instrument.

That said, learning to be able to play in more than 1 or 2 tunings, or using a capo, will enable one to play in more keys on an instrument of any scale.

Sorry, to answer the question, personal preference. If'in you like that sort of sound go for it!

The "36" inch is at least a fifth lower. I.D. slacked it a note or two below that so no issue with string tension. (Long neck banjo strings) And another tune on a "36" inch...

36 inch sound clip

Nate, listen to I. D. Stamper's long dulcimer for a possibility:

Hey folks just wondering what reasons people might have for preferring a longer scale length. I started off building dulcimers around 28-30" VSL, having heard that longer dulcimers are louder. Over time I've gradually made them shorter to make long stretches more comfortable, the most recent one being 23.5"
To me the tone of a longer scale seems a little fuller, but maybe I'm just convincing myself of that one.
I also appreciate the ever so tiny bit of extra space that you get between the frets in the second octave. A big downside to long dulcimers that I've noticed is that the packs of strings designed for dulcimers will be at a much higher tension than typical when brought up to Dad tuning.
So anyway just wondering what some benefits are for long dulcimers compared to short ones. Whether it be in the sound characteristics, practical reasons, play-ability, just anything that you tend to prefer on longer dulcimers. More perspective would help me to figure out what VSL I want to build at going forward.
Thanks
Nate