Trombone vs horns

When using the trombones and horns in their role as sustained harmony, and you have a passage that could fit easily in either section, how do you decide whom to score it for?

This is one of the trickiest things in orchestration, for me.

Is it dependent on what instruments are carrying the melody? Or, dependent on what dynamic you want? Or do you just use whichever instrument will create a fresher entrance at that point in the music?

Depends on the a lot of things. It depends on what sound you want, as a composer.

You should pay attention to factors such as, timbre, range, and whatever else you can think of. Do you want the brightness of the higher ranged horn, the mellow deep sound of the lower ranged trombone? Which sound blends in with the other instruments playing best, which one has the effect you are looking for?

In regards to the fresher entrance, it depends on if you want the fresher entrance or not :) So that one, it's up to you, people tend to like variety though. That one is totally up to you though.

I would personally say that dynamics is the least of your worries. Although, horns are better at staying in the background than trombones are. So it does depend somewhat on the instruments carrying the melody, if it's a harp, than you might not even include the brass...but if you were to, you should probably go with the horns. Same goes for if you have a couple of woodwinds carrying the melody.

I think the best thing you can do is familiarize yourself with both the instruments the best you can, then you can make these judgement calls with ease.

Alright, that's the best I can do, hope you get better advice :) and good luck.

no "versus" ..... both, and mixed too .... anything .....

and you forgot Wagner-Tubas .... they're very good to sustain harmony too ...

Generally, it will depend on the other instruments in the section(s) you are considering. Lots of woodwind instruments would lead me to use French Horns over Trombones. If Trumpets and Horns are already carrying a melody/counter-melody, then Trombones are the obvious choice.

And there's nothing wrong with giving Trombones the melody and sustaining harmony with French Horns either. There are just too many variables here to consider to just give you a straight-up answer.

At a similar played dynamic level, trombones will tend to stand out somewhat more than horns. For one because of the nature of their tones (mostly by the contrast of the cylindrical trombone bore and the semi-conical horn bore), but to a great degree also because of their sound radiation: The trombone projects its sound mostly directly foreward, so what the audience hears is mostly the direct sound coming from the trombone. The horns project their sounds to the right back first, where it's refracted by the walls, ceiling etc., so a great portion on the sound that arrives at the audience is reflected sound that comes from many directions at once and greatly depends on the acoustical properties of the room. This makes it somewhat less distinct and lets it melt together with the other instruments a lot more. The reflections at the walls and ceiling also absorb some of the overtones, making the sound even mellower (somewhat depending on the room).

That's also why I don't quite understand theOmasters assessment of "the brightness of the higher ranged horn, the mellow deep sound of the lower ranged trombone". Of course, if they play in their main ranges, the horn may seem brighter (just because its playing higher), but if both instruments are playing the same note (at the same, not too loud dynamic), the trombone will usually have stronger overtones (making it "brighter"), whereas the horn has the more mellow sound.

In traditional orchestration, there's of course also a certain symbolism that was commonly assigned to those instruments: The trombone sound was often considered solemn and ceremonial, often with connotations of sacred music (but also war), whereas the horn carried more connotations to nature, the hunt, etc. Such ideas are of course today mostly repealed, but certain archetypes have been carried on surprisingly long in the "classical" world, be that the "solemn trombone hymn", the horn fifth as the embodiment of the "natural horn sound", etc.

When trombones were used in past centuries for such sustained harmonies, it was often to create a sense of "pillars" that gave the whole orchestra a base and a somewhat "stately" mood, whereas the use of horns for the same thing was generally a more "subversive" thing: As an inconspicuous "glue", to make the orchestra sound somewhat "fuller" and give it a more "roomy sound", without actually sticking out. (With the downside that it can also make the orchestra sound somewhat more muddy if overused, or if the room and/or orchestra isn't adequate.) Again, of course, these clear uses (which, of course, were never -that- clear to begin with) have more and more dissolved over the last century - but the common acoustical effects are of course still the same. Horns generally tend to be rather inconspicuous at quiet dynamic levels, will increase the perceived spatial envelopment of the orchestra for the audience (due to the sound radiation), but will often be somewhat less distinct than the trombones doing the same thing.

Oops, I worded that badly. I was meaning within the instruments' ranges. Like the horn's brighter color in the higher range of the horn, or the mellower trombone in the lower range of the trombone. I was more going for the, you should find which fits better with the piece. If I were actually good at this, I might have even gone into something about the warmness of the horn's lower to middle range, or the trombone's ridiculously low guttural sounds. Sorry for the confusion.

Ahh, ok.

By the way: An interesting side fact is that technically, the F-Horn is actually tuned exactly as low as a tenor or bass trombone with an F attachment (likewise the Bb-Horn has the same length/fundamental as the trombone without F attachment). It is just the narrower bore (coupled with the small mouthpiece) that makes the lowest pedal notes harder to reach on the horn and much less common than on a trombone. But from pure tube length, both horns and trombones are "pitched" exactly the same (actually, even the tuba in F is exactly as long - it just has an even wider bore).