In addition to the tuba and euphonium’s natural amplification properties, they are also well-suited to amplifying via electronic means. There are numerous ways to amplify the tuba and euphonium: with a mic placed a few feet from the bell, closer to the bell, inside, and with contact mics directly placed on the instrument.
When amplified, the tuba/euphonium sound can be sent through a variety of different sound reproduction systems.
There are numerous issues to be aware of when amplifying the tuba and euphonium, the most pressing of which is the immense loudness already inherent in the sound of the instruments. Combined with an improperly calibrated sound system, this can lead to a variety of issues, including feedback, fatiguing sound levels, and a lack of tonal definition. The same issues apply for amplification through a standalone amplifier.
In the author’s experience, the best type of standalone system to use in this setting is either a keyboard amplifier or a self-contained PA systems. Both of these systems can sit on stage near the tubist, and with proper equalization and gain-staging, the risk for feedback may be minimized.
When amplifying the tuba and euphonium, the choice of which microphone to use is important. For distant miking (as in placed on a stand above the instrument), a condenser mic is the best choice. When placed closer or inside the bell, a dynamic mic tends to work the best (unless a clip-on mic is used, in which case the standard condenser works well). A few common microphones that work well for the tuba and euphonium include the AKG C414, the Shure SM57, the Sennheiser MD 421 II, and the Electro-Voice RE 20.
Regardless of which mic is used, it is absolutely vital that the chosen microphone exhibit a decent-to-excellent low range response (a minimum of 50 Hz, if not down to 20 Hz).
When used extensively, the act of amplification can become a part of the fabric of the composition itself; this is especially the case with both the work by Luigi Nono listed below and Monte Weber’s Colossus, the latter of which would be unperformable without the aid of amplification technology.
The notation of amplification methods is not usually a concern, but if this technique is notated, the usual rules for clear and consistent methodology apply.
Works to consider (bolded titles are particularly representative examples of this technique)
Post-prae-ludium ‘per Donau’ – Luigi Nono
Tube space – Dmitri Kourliandski
Colossus – Monte Weber