Can a saxophone replace a french horn in a wind quintet?

Answer 1

Yes, and no. I suspect far more no than yes.

First, tone. The french horn tone is utterly different from any of the saxophones. The Saxophone was intended to provide a string-like sustained tone to the wind band. There was never an intention of approaching the sound of the french horn, since that was already available, and Adolph Sax was trying to expand the sound-pallet of wind bands when he invented the Saxophone. It is the french horn's tone that keeps it as part of the woodwind quintet; as for brass quintets, the saxophone largely reproduces the tone of trumpets and trombones (without actually sounding much like them) and would reduce the tonal variety, considerably. (Many composers and arrangers discover, the hard way, that variety is what has kept the traditional woodwind and brass quintets in their accepted forms for so long!)

Second, attack. The french horn has a very characteristic "double blip" in the start of notes, which can be smoothed to almost nothing on quite notes but becomes quite pronounced at the higher dynamics. The saxophone lacks this characteristic. Eliminating this characteristic sound element would further reduce the diversity of sound in either woodwind or brass quintet.

Third, the sax is a considerably different instrument from the horn, with a completely different approach to sound generation, so that phrases which would be liquid and facile on one instrument would sound awkward and out of place on the other. This is one of those venn-diagram things, where two circles are overlaid, some of the area of each circle is superimposed, but each circle has area which does not jibe with the other. This is most-often a matter of taste, and requires consideration of the audience as well as the music director. (Sometimes, this works fairly well, like the canonical "What do I do, the Oboe player just swallowed his last reed!"..."Use a muted Trumpet!" joke.)

Finally, transposition. The horn is usually written in F, meaning that when the hornist sees a C in his music, the note he plays comes out as F in "orchestral pitch". The Saxophones are pitched in Bb and Eb, so any F horn parts will require transposition. There are Eb horn parts, which would be directly readable on the proper-sized sax, but the Eb horn is even more sonically removed from the sound of saxophones that the effect could be anything from annoying to unacceptable, even to completely untrained and unfamiliar non-musicians.

So largely, substituting a sax for a horn would be a good thing only in cases where the necessity is so great, or the desire to fit a player who only plays sax into a quintet so pressing, that it would outweigh the affects.