Of all instruments I would say the pipe organ, probably by some margin. Of orchestral instruments I would have thought it was most likely a percussive instrument such as the Timpani. I found this article claiming it is the clarinet but I am not totally convinced. I am confident one of our resident recording engineers will be able to provide an authoritative answer!

If dynamics is the difference between piano and forte then it could well be the clarinet. I was thinking that say the trumpet would be louder than the clarinet but then how softly can you play the trumpet?

I've been jolted out of my seat by the timpani and my hair parted by the trombones and knocked off the stage by a 9' grand piano, but I have to vote for a full-bore pipe organ as the most dynamic instrument that I've ever heard. Good Lord, the trumpet register alone is like the most incredible trumpet section you could hear, then add the huge bass pipes and the potential to get it all blowing full-force with several registers at once and you've got a hell of a noise.

Clarinet?? Pooey, I see no way, unless it's an ugly, loud noise contest. That squeaky honk they can do is really nasty, but I can't imagine one of them being the loudest.

Dave

Quite softly with a mute.

In fact I can't off-hand think of any modern orchestral instrument that can't be dynamically modulated by the player, i.e. where the player can't somehow contrive to produce a ppp note (although I have this sneaky feeling I will be eating these words pretty quickly )

Oh yes, the trumpet can be played very, very quietly.

Dave

The cannon from the 1812 Overture, duh!

It is generally accepted that the orchestral instrument with the greatest dynamic range is the French horn.

(Horn trivia: American players eschew vibrato, just about every other country's horn players use vibrato. Every other instrument uses vibrato, except for clarinet in an orchestra. Weird, huh?)

Trombone can produce the greatest SPL (with trumpet fairly close).

Clarinets can begin a tone so quietly you cannot hear the beginning of a note (and because of this probably challenge horn for dynamic range). Violins can also whisper.

All orchestral instruments well-played can project to the back of a large hall with a piano tone. (Fascinating how intensity and projection is not a function of volume.)

Trumpet is the most physically demanding to play. For example, the internal psi generated is incredible and even easy practicing can make the player break into a sweat.

IMO, trumpet is also the least forgiving and the harshest mistress. Take a day off and you lose part of your ability; there is no such thing as a truly easy, absolutely simple to hit note; no matter how well made the instrument has notes which are inherently out of tune; you don't know how well your gig is going to go until you warm-up, some days are just bad, etc.

Quote:
Trumpet is the most physically demanding to play. For example, the internal psi generated is incredible and even easy practicing can make the player break into a sweat.

You sure its not the Oboe for the same reason?

Oboe is surprisingly taxing. The biggest problem is that one runs out of oxygen before running out of breath. Thus, breath control is particularly challenging.