1) Check Response – See how easy it is for you to make a sound. Are true PPP sounds possible? Does the horn respond quickly and have a “pop” even on soft articulations? How is the resistance of the instrument and is it comfortable to play against?
I tend to use something low and stepwise to test this aspect and incorporate “P” articulations in whatever I use. Clarke technical study 1 or 2 works well as do scales and arpeggios.
2) Check evenness through the registers (including intonation) – See if the horn remains comfortable to play through the range. Does the blow resistance change considerably in any one register? Do notes slot securely through all ranges? Does any one partial feel or sound strange? Is the horn in tune with itself?
I tend to use Stamp, Cichowicz, arpeggios, and easy/slow partial slurs to test this aspect. Multi-octave scales can also work.
3) Check Tone Quality – See if the horn’s characteristic sound closely matches your ideal sound. Can you make every tone color you want on the instrument? Can you adjust the sound? Brighter? Darker? Narrower? Wider? How easy is vibrato on the instrument? Keep in mind that you can adjust the “base” sound with your mouthpiece selection while the “adjustability” of the sound is harder to expand.
I tend to use short excerpts from several pieces of different styles to test this. Long tones (while changing the quality of sound) also work well for this.
4) Check Flexibility – See if you can move quickly and accurately through the horn. Can you skip partials cleanly? How quickly can you go through your entire range? Do fast finger dexterity passages speak cleanly?
I tend to use Irons and Bai Lin partial exercises, multi-octave passages, lip trills, and Clark Technical studies to test this.
5) Check Articulation – See if you can apply a variety of articulations to a note. Do you have a good “pop” on each standard articulation? Can you get rid of the “pop” for a smooth articulation if needed? Can you accent a note cleanly? Do multiple tonguing passages speak cleanly in a variety of styles?
I tend to use Arban Exercises, Vizzutti Exercises, and short solo excerpts to test this.
6) Play a Longer Excerpt – See how comfortable the horn is overall. After spot testing each aspect of an instrument make sure that it is comfortable to play overall. Can you create compelling music using this instrument? Is the instrument easy to play as a whole?
I tend to use a combination of solo pieces, excerpts, and etudes for this final test of an instrument.