**Music Theory: Tune Lengths, Part Four**

December 2, 2018

This is the fourth post in the series. The first post was about why jazz musicians should make their songs 3-4 minutes long, the second post was about related mathematical equations, and the third was about practical applications. (Read these if you haven't already.) This post, as well, will be about practical applications.

In our third post, we gave an example of a medium-tempo song (128 beats per minute) with 3 and a half choruses that took 3 and a half minutes to play. We then divided the solos in ways that gave multiple musicians opportunity to solo; however, they didn't always have a lot of time to improvise, just enough.

We finished our third post with a new principle:

A song's tempo and its total length in beats are directly related if the song's total length (in minutes) is constant. For example, if a song's total length is 128 beats, we can assume that if a song is 1 minute long, the tempo must be 128 beats per minute.

We'll now do an example different from the one in the third post (which was medium-tempo). This one will be up-tempo:

It's a song at twice the speed - 256 beats per minute. The total length of this new song will be 3 and a half minutes, the same as the other one. Each chorus will be 32 measures, so now let's calculate:

If 128 beats per minute for 3 and a half minutes means 3 and a half choruses, then...

...256 beats per minute for 3 and a half minutes equals 7 choruses.

We'll create a diagram representing our faster, 7-chorus song. Vertical lines will separate the choruses, and C's will stand for each chorus:

C | C | C | C | C | C | C

Now, let's assume that we've got a trio: piano, bass, and drums. We'll divide the solos so everyone gets a chance to solo:

Black = tune, played at the start and end

Red = piano solo

Purple = bass solo

Blue = drum solo

C | C | C | C | C | C | C

Now we'll apply the same to a quintet:

Black = tune, played at the start and end

Green = trumpet solo

Purple = saxophone solo

Blue = piano solo

Red = either bass or drum solo

C | C | C | C | C | C | C

In each one of these, everyone gets at least a chorus. The choruses go by quickly, but still, especially for the first soloist (trumpet in our example), there's quite a lot of time.

Hopefully, from this series you've learned a lot about how divide up the lengths of a song. The series ends here, at least for now.