The Synth-1 allows you to create fuzzed-out synth waves!  Use the Filter and Blend controls to mix your guitar with the fuzz from the synth.  Go from churning slow-gear reverse swells to sounding like a light saber.

The Keeley Synth-1 is a guitar-triggered, single-note wave generator.  You control the tone of the wave with the Filter Control.  The lead-in time or swell of the note is controlled with the Attack knob.  Then use the Blend control to remove the natural tone from your guitar as you slide through synth-sounding fuzz waves.  Use an expression pedal to control the Filter, and now you have Wah-Wah-like control of the Synth-1.