Easy, easy, dear forum members - no hard feelings in this thread. [:)]
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William, the quest for "the" string sound is probably as old as orchestral recording itself. Leaving the more obvious main factors like the composition, the arrangement, the performance and the acoustics of the surrounding room aside for a moment, I dare to suggest that even in seemingly puristic productions the techniques of sculpturing this sound were always used to their fullest extent; the style of doing so was dependant on the respective era, of course.
Given the "raw" nature of our samples (in the best sense of the word), many ways of audio-processing make sense. This ranges from simple, static EQing to sophisticated DSP like convolution - the latter not only for reverberation, but also to mimic a certain signal path, or even "dry" resonances.
Personally, I tend to use a combination of several tools. Most of the time I start with some basic EQing, emphasizing the "body" of each section, while getting rid of the (mostly scale-dependant) resonances that colour the sound too much. The next step ist to tame the "shrillness" (is this a word?) between 2 and 4 kHz. This is _very_ much dependant on the arrangement: Sometimes it is necessary to cut here two or even three small frequency bands by 8 or even 12 dB; on other occasions, this would make the overall impression too dark and indirect, and a broad dip by 3 dB centered around 3.5 kHz is more than enough. More often than not, I add some kind of harmonic distortion, be it from analogue equipment (older tube gear comes to mind) or on behalf of saturation coming from tape-emulations or the like. This blurs the pureness of the harmonics in a good way and adds interest and variation to the sound.
In pieces with extreme dynamic changes from pp to ff it is sometimes impossible to find one setting for all occasions. In these cases, I like to use dynamic EQs (resp. multiband compressors) that reduce the volume of a certain frequency range only if a certain threshold is reached. This seems to be tricky, but the results are self-explanatory once you try it.
While it seems to be contradictory to what I just described, I sometimes _add_ some very high treble to violin-sections, for example a soft shelving EQ above 12 kHz or higher. Here, the quality of the EQ is crucial, of course - this is true for virtual orchestration as well as for live recordings.
The final step is some kind of reverberation, most of the time. Your options range from a very clear, unobtrusive synthetic reverb, just to add that certin feeling of "air", to samples of real halls - rich and full of character. Again, you should treat the reverb as a signal of its own (like an engineer would optimize the ambience-tracks of his recordings). Use EQs and all sonic tools you feel that are necessary (but not more [;)] ...). The crucial point is the balance between dry and wet signal. You may understand that there are hardly any guidelines for this, as it depends totally on the context.
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I hope this gives you some starting points for your own solutions. - As this thread has turned towards a more technical POV now, I will move it to the "Mixing and PostPro"-section of our forum, where other users will most likely look for this topic first.
All the best,