In order to tune a cello, it will help if you first make sure the bridge is in its proper position. Each string on the cello must then be tightened or loosened using the tuning pegs to bring the tone close to the note it should be. Once the strings are close to the proper note, you can use the fine tuners to perfect the pitch so that it is neither too sharp nor too flat. Often, to tune a cello properly, each string will need to be tuned and re-tuned several times in one session before the instrument will stay in tune.
Before you begin to tune a cello, it is important to make sure the bridge is properly placed. The bridge, located on the body of the cello, is the part that raises the strings up off the instrument. It should be upright, straight and parallel with the fingerboard. The tautness of the strings holds the bridge in place, which means if the strings become loose during the tuning process, the bridge might shift out of place. If the bridge is tilted or on a slant, it will be extremely difficult to tune a cello.
Once you are sure the bridge is in place, set the cello upright as if you are going to play it, and begin tuning one string at a time. It is best to start with the “C” string, which is the thickest string, so that as you tune, you will not inadvertently put too much stress on the thinner “A” and “D” strings. If you use a chromatic tuner, simply pluck the string and turn the tuning peg for the “C” string until the chromatic tuner indicates you are close to the appropriate note. In the absence of a chromatic tuner, this process can be done by ear, using the middle “C” note on a piano or pitch pipe.
Repeat the procedure for each of the strings, bringing each one as close as you can to the corresponding note. Make sure to exert a fair amount of inward pressure as you turn each peg so that it will stay in place and not slip back once you have adjusted the string. After you’re done tuning each string with the pegs, to tune a cello more precisely, you can use the fine tuners located on the tail piece. Pluck each string and adjust the fine tuner to bring the string into accurate pitch in accordance with the chromatic tuner, piano key or pitch pipe.
Once you’ve finished tuning the last of the four strings, you will likely have to tune each string again, possibly several times, before it will stay in tune. The reason for this is that the neck of the cello will stretch and contract as you are tuning and consequently, the strings will get thrown out of tune. The neck will eventually settle and the strings will retain their position, thus staying in tune.
As a caveat, if the cello is terribly out of tune, it is best to work with each string a little at a time. Do this by alternating between the strings, bringing each gradually in tune, rather than tuning one string completely before moving on to the next. If you tune a cello that is badly out of tune by tightening and adjusting one string completely before working with the rest, it will put uneven pressure on the bridge and probably cause it to move or break.