Help. Bought a JP 8000 and need to know...

[keepit80s]

....how to make a sound 'straighter'?!

The sound I want is at the start of here: http://www.youtube.com/watch?v=BzdHxqwTO-4

For example, performance 11 has a short arrpegiating bass not, which 'resonates' (I think that's the effect I am hearing (ie the sounds seems to be in a cycle of sounding 'brighter'). I just want the sound to stay the same.

I have tried changing resonator but the wave form still seems to do it, although of course sounding duller. is it more do to do with the waveform?

What is it I need to be tweaking to make it straight?

It will be obvious to you that I am not a natural analogue user! Can anyone advise?
Thanks