I have often been asked, "How do I write horn parts for my (Jazz combo, R&B horn section, Ska band, etc.)?" or "How do I get that sound for the sax section?"
I will show you the techniques I have used successfully for many years of writing for saxophone quartet, theater pit orchestra, jazz band, and R&B bands. I will make the assumption that you already know practical ranges for the instruments you will be writing for, how to transpose for them, and understand the basics of harmony. This series will NOT be basic music theory. I will discuss the techniques of writing real music for real musicians!
The simplest and most basic harmony is the unison-octave line. Never underestimate the effectiveness of this technique. For the small combo that has only two horns, I suggest the trumpet and tenor sax, rather than alto sax. The alto is too close to the trumpet range, and is limited on the bottom end. The tenor has a better range for being written one octave below the trumpet.
For this type of line, simply write the part once, and both the trumpet and tenor player can play off the same part:
Exp. 1a, Concert pitch:
Exp. 1b, Written parts:
Orchestration for Saxophones - Part 1
Notice that in the above Example 1b, the parts for trumpet and tenor sax look identical, but they actually sound an octave apart. Both instruments are in a very strong register. The result is a solid, powerful horn line for a small jazz combo, pit band, or R&B band.
Another useful technique is to write the two parts in a simple harmony, usually thirds. First write the lead part, in this case in the trumpet. Next write simple harmony a third above it. Now transpose both parts up one step as if for trumpet. But the higher harmony part will be played by the tenor sax, and actually sound a sixth below.
Exp. 2a, Concert pitch:
Exp. 2b, Written parts:
Finally, unison-octave and simple harmony may be mixed for effective two part writing.
While these sax parts could also be written for alto sax and still be in range, overall, the tenor sax is a better choice for this type of writing and playing.
Next, three part writing.