Re: how to make a great 808 kick in sylenth!?
Layer a real (dry) and fairly short kick with sylenth1 single sine wave. Play it low. Make it monophonic. Saturate the sine (to create some overtones/harmonics) and put a lowpass filter after it. Adjust amplitude envelope (release mostly) to taste. Maybe also add some attack time, to avoid clashing and overlapping with the kick drum (sampler or timeline).