SlackBuildsOrg/audio/whysynth

WhySynth is a versatile softsynth which operates as a plugin for the
DSSI Soft Synth Interface and is useable with apps like Qtractor and
Ardour.  It features 4 oscillators, 2 filters, 3 LFOs, and 5 env
generators per voice, plus effects.  

It also has many pre-sets, so if you just want to install a DAW and
a soft synth so you can start noodling around with neat synth sounds,
start with this one.

It requires:
* dssi
* liblo
* ladspa_sdk

All available from slackbuilds.org

You'll also want to install:
* a DAW like Qtractor or Ardour (available via SBo)
* JACK (try qjackctl from SBo)
* real time priorities (easiest via the 2.6.38.4 kernel, 
  available in Slackware /testing)
* set_rlimits (available via SBo)