String Tension Explained

Surprisingly, tension is easy to measure on a string (the vibrating length of the string is measured and weighed).  And while it can provide us with some information on how the string will behave, it says little about how the string will actually sound.

The key variable tension can give us is an indication of is the string's impedance.  Put simply, impedance tells us how much energy the string can carry and relay onto the instrument.  The higher the tension, the larger impedance, resulting in a louder sound.

But it does not tell us anything about the string's frequency output, ie the instrument's quality or timbre of sound.

A Cello’s changing shape with strings

Admittedly, the cello body's shape does change slightly when there are no strings attached to when strings are tuned onto the instrument.  But the impact to the shape between high and medium tension strings is too slight to have any noticeable change. If you don't believe us, there's a very simple experiment you can perform to prove this to yourselves.  Read our article on "string tension proved" for instructions.

But tension can still be a useful measure from a player's perspective.  High tension strings, because of the greater levels of impedance, need more energy given by the player in order make them sound.  They are more power hungry and can sound louder.  But they are also harder tocontrol ,especially at lower volumes.  No surprise then that "soloist" strings tend to have higher tensions (as more skill is required to play them).

Higher tension strings however have one key advantage aside from sounding louder.  They maintain their intonation more easily at a range of pressure levels.  Take the C string for instance.  Try playing the same note with light and then heavy bow pressures.  The pitch should rise.  This is particularly pronounced on low tension strings while the higher tension equivalent will maintain its pitch much better.

So to conclude, be weary of focusing too much on string tension.  It is the easiest piece of "technical information" you can get on strings, so easy you can calculate it yourself. But sound wise, there are other factors which merit more thought.