What is the largest and lowest brass instrument?

The tuba is recognized as the largest and lowest brass instrument in orchestras and bands. Its structure features a wide bell and extensive tubing, which contributes to its deep, rich sound. The design allows the tuba to produce the lowest pitches within the brass family, making it instrumental in providing harmonic foundation and depth in various musical settings.

In contrast, the trumpet, while notable for its bright and penetrating sound, is smaller in size and plays higher pitch ranges. The French horn is also significant in the brass family and has a unique mellow tone, but it does not match the tuba in size or pitch range. The trombone, while larger than a trumpet and capable of playing lower notes, still cannot achieve the low tones produced by the tuba. Thus, the tuba stands out as the largest and lowest brass instrument.