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
Screw high order harmonic distortion. Harmonic distortion is related to the signal itself. IM distortion is, by definition, enharmonic, and much worse. Many factors contribute to sweet sound, frequency response, harmonic distortion spectra, amp behavior at clipping, room treatment, etc., but a lack of IM distortion is certainly one of them.
Viridian, I agree with your comments about the importance of having minimal IM distortion, and I would additionally mention TIM distortion.

But note that I referred to harmonic imbalance, not harmonic distortion. The distinction being that I was using the term "imbalance" to encompass a much broader set of ways in which the harmonic structure of a musical note can get messed up (just one of which is harmonic distortion), including frequency response unevenness and the other variables I mentioned in my earlier post.

Regards,
-- Al
Strings shouldn't sound overly aggressive, but they also shouldn't sound too sweet. Depending upon the instrument and the player it can be very appropriate to have a little bite or even rasp to the sound. The choice of microphone and its placement are the biggest factors in string recorded sound quality.
What Onhwy61 said is exactly on the mark, as LIVE stringed instruments can sound very strident, when bowed aggressively. Good recordings will reproduce the edginess/bite, epecially if the mic was placed in front of the instrument.
I fall into the microphone camp of believers, at least, most of the time. So often, one sees a microphone just above and oh so close to the instrument during recordings.
I suspect this was done in the past to compensate for (older) home equipment that had difficulty reproducing high frequencies. Unfortunately, the practice still seems to be in effect, even though the compensation is no longer necessary, and now, is even objectionable.