Open string tuning
As one who often bashes out the opening of Bruch's G minor concerto (mainly for assessing violins) I'm just wondering how a real violinist would tune for it? Obviously the G string needs to be spot on, but would you tune two Pythagorean fifths down from the oboe's A and the E string a perfect fifth higher? If so, and the orchestra tunes from the soloist's G, the open E is going to sound pretty sharp.
Sassmanshaus advises the soloist to tune his or her violin to the highest "A" that (s)he hears in the orchestra. He says that will make you sound more brilliant. If you do this, it's doubtful your G will be too low even if you tune two Pythagorean fifths down.
It's all fudge really, isn't it? A 4-note chord of G G C E from a violin tuned in perfect fifths sounds perfectly acceptable to me, maybe just because I've got used to it. Even when you add another perfect fifth from the viola open C my ear usually seems to tolerate it OK. Discrepancies of this sort seem far more noticeable on a piano. I wonder if that's what vibrato is really for, to create a fudge zone of acceptable uncertainty? Not much use for open strings though.
I have read somewhere that the limit of human pitch discernment is about 4-6 "cents" or 1/20 of a half-step( wow!) [100 cents = 1/2 step ]. Tuning in perfect fifths will put the open G at 4 cents lower than equal-tempered piano G. And the orchestra will not be playing in equal-tempered tuning anyway. Cellists and Violists will sometimes need to tune the C string up a little when doing chamber music with a piano, depending on the key. The perfect-fifth C will be 6 cents lower than the piano C. I read that the Viola soloist William Primrose, when working with a pianist, would tune to the piano D, not the A. The pitch differences are most noticeable with the major and minor chords. The difference between the Pythagorian (melodic) and the just (chordal) third will be the very noticeable "comma", 20-24 cents, with the equal-tempered third splitting the difference. Vibrato does in fact cover up the problem, but that's not the main reason for using vibrato.
In another recent thread I don't there was much consensus on the main reason for using vibrato. But apart from simply "covering up poor intonation" I don't believe anyone suggested this one which I submit might be added to the list.
I think one would be foolish to trust the G string to on-stage tuning. Seems like a back-stage job to me - check at rehearsal with whoever has the simultaneous sustained note at the solo intro. Anyone doing this in concert is bound to have done it before.
I don't think vibrato exists to cover up bad intonation, even in part. It sure doesn't help my thirds any. :(
Well, when I was first introduced to vibrato and became reasonable familiar with it my violin teacher quipped: "You have already figured out how to use vibrato to fake your intonation!" At least she thought there was something to it.
I think one reason why it can be hard to play senza vibrato is that we've all (or should I say "I've"?) developed an instinct to wobble as soon as we hear a sound that is fractionally out of tune.