When it is found necessary to double the bass in octaves, the too resonant trombone and tuba are seldom used, the duplication being effected by the bassoon, as explained further on. The quartet of trombones and tuba is not often employed in close four-part harmony; the third trombone and the tuba usually form the bass in octaves, and the three upper parts are generally allotted to the two remaining trombones reinforced by a trumpet or two horns in unison, so as to obtain a perfect balance of tone:
I have often adopted the following combination of brass instruments, and consider it eminently satisfactory: 2 horns and tuba to form the bass in octaves, the three other parts given to the trombones:
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In the higher registers, four-part harmony, of which the two upper parts are given to the trumpets, may be completed by two trombones or four horns in pairs:
When 3 trumpets are available the fourth part should be allotted to one trombone, or two horns in unison:
