What makes strings sound "sweet"?


I have always wondered about this. If you listen to many recordings of bowed string instruments, then you know that the upper registers can sometimes have a sweet tone. I define this by what it is not - edgy, brittle, dry and rough sounding. It is smooth and inviting. I used to assume this was due to rolled off highs or an emphasized midrange, but I am not so sure. It varies by recording, or course, but I have often wondered what, in the recording or reproduction process, causes strings to either sound brittle or sweet. Is it the acoustic of the original recording venue? A frequency balance issue? I would love to hear from those who might know. Thanks!
bondmanp
Thanks, all. Very interesting replies. Kijanki - thanks for all the info, but my OP specified "recordings" of bowed string instruments. Music is, for me, stricktly a spectator sport. :-)
Ahh, yes. This is absolutely the hardest element for a stereo to convey. I used to think bass was the hardest. Then I thought the midrange was the hardest. Now I appreciate that the sweet, angelic, gripping sound, detailed, grain-free sound of the treble is one of the most magical, mesmerizing, and elusive pieces of the puzzle.

The recording is important, but so is your stereo. I have built my stereo in the quest for this sound. Everything contributes, although I place high emphasis on the Jade Audio cables, the preamp, the Tripoint Troy, and the diamond tweeter. I believe it really becomes an issue of striking the correct balance of frequencies throughout, and removing all the noise (both heard and not heard).

It is so fragile. Just changing one cable can kill the magic. If you have it, be careful not to touch the stereo again or all is in jeopardy.
Bondmanp- It was intended as a joke but in a process I learned how difficult it is to play violin. In addition to technique and intention of the player there is a sound of instrument, acoustics, recording techniques etc. Radiation pattern of instruments can be also strange with some instruments like cello projecting only to the rear at certain frequencies.

Strings sound much better now with my my new speakers but I can hear big difference between recordings varying from sweet earthy tone with beautiful harmonics to high pitch screeching sound. My gear have deficiencies, I'm sure, but some recordings are just plain wrong and no gear in the world would make them sound great.
"This is absolutely the hardest element for a stereo to convey. ... The recording is important, but so is your stereo."

Agree 100%. Subtle weaknesses in source, pre-amp, ICs, and/or power amp together will often exhibit themselves here during a well recorded sustained string note. Speakers too but perhaps to a lesser extent in general in this regard. To get this detail to sound consistent and natural and not distorted in subtle ways from start to end is an ultimate test. I used to think that this was the blatant achilles' heel of CD digital. Now I think it may still be the weakest area of CD sound recordings, but not to the extent where it always must sound problematic due to the recording technology.
Agreed for the most part, Mapman and Kijanki. I have some recordings that have sweet string sound on almost any system I play them on - even my all-original factory-equiped Subarau car stereo! OTOH, I some recordings that have screechy, dry sounding strings on every system I play them on. So, IMHO, this seems like a more recording-dependent issue than some other sonic traits. And, Mapman, I have heard both of these traits on vinyl as well as CD.