Proper tuning is essential for a tuba player's sound and a band's sound. A good, in-tune bass section is much more powerful and adds more to the band's overall sound. A in-tune tuba will also have better response and evenness.
Unfortunately, properly tuning a tuba is a series of compromises - no method will result in a perfectly tuned instrument.
This article will offer my method for tuning, one that is commonly taught.
In this method, the low register is most important. While tuning, one note will be in tune while another note with the same valve combination will not. I recommend basing the tuning on low register notes because "lipping" notes to the correct pitch while avoiding distortion is more difficult in the lower register.
Open Tuning (Main Tuning Slide)
The first thing to do while tuning a tuba is set the low open partial (BBb tuba, low Bb; on CC tuba, low C; on F tuba, low F). Make sure this note is in tune, with a good sound.
Next, try the higher partials and make a good compromise between them, but remember that the low partial is most important. This compromise will be different with each instrument and player.
2nd Valve Slide
Next, tune the 2nd valve slide. This should be a true half-step below the open tuning and should have a full, powerful sound. Again, check the upper partials and make compromises only if absolutely necessary.
1st Valve Slide
Tune the 1st valve slide. It should be a full whole-step below the open partial. Check the upper partials.
3rd Valve Slide and 2 & 3
The third slide tuning is important. Tune this slide to a full 1 and 1/2 steps below the open low partial (BBb tuba, G; CC tuba, A; F tuba, D). However; play a note with the valve combination 2 & 3. If this is sharp, add some additional length to the 3rd slide. The 3rd valve is rarely played on its own.
4th Valve Side and 1 & 3
Now tune the 4th valve slide to the low partial (BBb tuba, F; CC tuba, G; F tuba, CC). This should be solidly in tune, as it is common in tuba parts. It is also a very powerful note for most tubas, so it should be in tune without worrying about lipping up or down.
If this leaves the whole step above the low partial a little flat (C on a BBb tuba), 1 and 3 should be a good alternative, since we made the 3rd valve slide slightly longer than it needed to be.
Slight adjustments will likely need to be made after tuning, due to the differences in horns and players. This method is by no means the only method used to tune a tuba, but it is the method I prefer and is taught to most tuba players that I know.
-- Mike Quain
More at my website http://www.ultimate-tuba.com