melisma extender line minimum length

Question

I have this kind of music containing a melisma:

\relative
{
  c'4. e8 g4 c a c8 a g2
}
\addlyrics {
  Al -- le Vö -- gel sind schon __ _ da,
}

I get this:

The melisma extender line (after schon) is present, but barely noticeable.

How do I force it to be longer? (which will result in a larger distance between the two eighth notes, of course)

---

I know how to force the hyphenation to be longer:

Adding \override LyricHyphen.minimum-distance = #4.0 before the notes will give

, so I thought there is a similar option for the melisma extender line. But \override LyricExtender.minimum-length = #4.0 doesn't change a thing, so it's probably not the right option.

---

Following Richard's answer, I wrote this

\relative
{
  c'4. e8 g4 c a c8 a g2
}
\addlyrics {
  Al -- le Vö -- gel sind 
  \override LyricSpace.minimum-distance = #8.0
  schon __ _
  \revert LyricSpace.minimum-distance
  da,
}

and got this:

The length of schon__ and the distance between its corresponding notes are exactly what I want, but the distance to the next note (the one corresponding to da) is too large. I want that distance to be default. I tried reverting the LyricSpace override right after the __ (before _) but the result is the same.

Answer 1

You're almost there! Using \override LyricSpace.minimum-distance = #1.0 is what you're looking for. This changes the space between the words (or syllables) themselves, in doing so also changing the distance for the melisma line.

Like with change the LyricExtender, you can change #1.0 to whatever value best fits your scenario.

Answer 2

I found this piece of information in LilyPond Internals Reference regarding LyricExtender:

minimum-length (dimension, in staff space): 1.5

Try to make a spanner at least this long, normally in the horizontal direction. This requires an appropriate callback for the springs-and-rods property. If added to a Tie, this sets the minimum distance between noteheads.

After googling a bit, I found a snippet that showed how to do that callback. So I wrote

\addlyrics {
  \override LyricExtender.minimum-length = #8.0

  % do the callback
  \override LyricExtender.springs-and-rods = #ly:spanner::set-spacing-rods
  
  Al -- le Vö -- gel sind schon __ _ da,
}

and got:

So forcing a minimum length this way works and does not affect the distance between the last note of the melisma and the next note (as Richards solution does).

But it's still not what I want. I didn't say this in the question, but in fact I want

• a minimum length of the melisma (done!) and
• the end of the melisma extender line and the last note of the melisma should be aligned (not done!).

I found a way using LyricExtender.right-padding. Unfortunately, it requires trial and error to find a good value and the value needs to be changed whenever any other spacing changes (e.g. by changing paper size or doing a manual break somewhere in the notes). But a bad solution is better than none. Here goes:

\addlyrics {
  \override LyricExtender.minimum-length = #8.0
  \override LyricExtender.right-padding = #2.0
  % do the callback
  \override LyricExtender.springs-and-rods = #ly:spanner::set-spacing-rods
  
  Al -- le Vö -- gel sind schon __ _ da,
}

which will produce