change default horizontal spacing

[James E. Bailey]

I'm wondering about how I can change the default horizontal spacing, at least for dynamics, so that rather than adjust them up/down, lilypond adjusts the measure width.here was my generic input file:
\header{  title = "A scale in LilyPond"}

\relative {\time 3/4  c\ppp d\pp e\p f\mp g\mf a\f b c\ff d\fff }

\version "2.11.42"

While I'm not particularly fond of how wide the spacing in the earlier example is, I prefer it to the spacing in the later example. So, I'm starting to wonder about how I can get somwhere in between.
sample file from version 2.11.44

sample file from version 2.11.48