Beam slope tweaking

[Víctor]

Hello everyone:

I'm trying to make beam slopes parallel to the music, or at least more 
evident. So I'm using \override Beam.damping = #0 wich works mostly ok, 
but beams in the center of the staves are still very horizontal. I've 
also tried to mess around with Beams.details list, but I can't figure 
out what of most of its keys do. Is there any way of increasing the 
slope of beams in the center of the staff?

Thanks in advance. Víctor.