It's been said that a mandolinist spends half the time tuning, the other half playing out of tune. If you do a google search, you'll find this joke is attributed to harpists, classical guitarists, and a myriad of other instrumentalists. If you want to get technical, this is more apparent (and literal) when you study the notion of equal temperament tuning.

We don't want to get to technical about it except to say the nature of pitch is relative to the fundamental of the root of a scale, and when it's divided out in 12 steps, it's not consistent from key to key. The 5th is close (but not perfect) and the 3rd can be way off by the time you travel around the circle of keys. An innovation in the 18th century set up a kind of compromise tuning known as "equal temperaments" but even in the 19th century many classical composers wrote piano music for "Just" and other variations of the temperament. If there wasn't a lot of modulation, it wasn't that much of an issue. Today's music (especially atonal or 12-tone) requires a compromise temperament, and it's the same with a fretted instrument like the mandolin.

It's really not an issue for most, but if you're playing with a fiddler or a wind instrument, chances are they are incrementally adjusting their 3rds and 5ths in long tones and this might explain the perception of a guitar or mandolin being out of tune despite exhaustive efforts with an electronic tuner before and during a performance.

The difference is quite a bit more obvious in a harmonica, and we stumbled on a website where this is demonstrated aurally. You can really hear it in the chords.

Visit site:
Audio Examples of Just Intonation and Equal Temperament Applied to the Harmonica
Read more about Well vs. Equal Temperament

Explanation of other temperaments: The 12 Golden notes is all it takes...

Posted by Ted at June 20, 2013 2:20 PM