La Folia

A temperature change could drastically change the relative humidity and the hair length.

Gosh, I just had another look at this poor thing. There are definitely some cracks. I think BOTH blocks are cattywumpus. Contrary to what I wrote, the top DOES have some wood spliced in at an odd angle. And the open seam in the back requires expert attention. It looks as if it may have had an amateur repair attempt, with oddball glue added, which would require extra work to undo. I think it needs major repairs. Both blocks and both plates. I think repairing both plates adds to the complexity. Whatever you do, don't try any of the repairs yourself unless you are an expert.

It looks to me like the top is sinking rather dramatically.

Since there is some question about possible damage, you could remove the chinrest. It's not part of the instrument anyway. Just be sure to turn the screws the right way.

I don't see evidence of repairs, although your pictures don't show very much. To my eye it looks like the maker may have been self-taught, but that is common for many of these instruments. The workmanship is not outstanding, but not bad either. There is a crack in the top, but that's not unusual. Normally the top of a Hardanger fiddle can be removed and repaired just like any violin top. Only you can see if there is more damage. You might find more when an expert removes the top. It would be nice if you could post better pictures. There is an article on how to post pictures for identification pinned near the top of this forum. The pegs look typical of the breed, and they will require some attention. Make sure you save any little pieces that you may find. And put some padding under the tail piece so it doesn't scratch the top. They should be worked on by someone who is familiar with Hardanger fiddle pegs. The peg heads are part of the instrument, and not disposable, as they would be for a violin. Don't try to string it like a violin or with violin strings. It looks like someone has tried to do that, and it doesn't even have the understrings. You need Hardanger fiddle strings. Be sure that whoever works on the instrument is an expert repairman who is aware of the special characteristics of Hardanger fiddles.You can find resources, including repair persons, from the Hardanger Fiddle Association of America web site, http://www.hfaa.org. David Golber has a booklet on what your repairman should know about Hardanger fiddles.

You might want to include Hardanger fiddles, and maybe even nyckelharpas. There is quite an active culture. Although somewhat close to violins, there is a distinct cultural difference.

That holds the diaphragm that produces the sound. See my link to the Wikipedia article, above. I don't know what the cord is. It may indeed be electrified.

Stroh violin

I suppose the warping is repeated for the same reason it warped the first time: someone isn't taking proper care of it, and has no idea how to take care of it.

San Antonio Shoes factory tour

Hmmm. Whatever the merits or demerits of slab-cut backs, I notice that Strad made quite a few of them. I myself have a nice, very stable 97-year-old Strad copy with a slab back.

I am mightily confused. To me this looks like a VSO, and nothing that would be associated with a known maker. There is something about this conversation that I don't understand.

No, no upscaling. It's called "cloning", where one part of the image is copied to another in order to fix defects in the image. It can be done better than this so it's difficult to detect.

In the thread quoted by Stephen Fine, a Tascam hand recorder beat out some more sophisticated economy alternatives. A happy ending, I thought. Stephen Fine, thanks for reposting that thread. I had assumed it disappeared into the ether, and I had actually forgotten the results.

You need to rearrange your sets or get different friends. You can't reasonably expect to change tunings like that. It takes a bare minimum of a minute or two to get it into a different tuning and keep it there, unless maybe you're using steel strings (ugh)--or you just don't care about getting it in tune. You'll just stress the heck out of everything if you keep jerking your instrument around like that. Against my better judgment I've been known to change tuning (once) during a set, but even so I don't rush into it. Gimmicks won't work, and you'll just look goofy if you try. You could make a capo, but I'd rather eat a bug. I concur with everyone else. The old ways are best. Either get two fiddles or cross-tune infrequently and leisurely.