Keeley Seafoam Plus 

robertkeeley.c... Seafoam Plus Chorus - True Chorus and ADT with Reverb
Keeley Engineering is changing the minds of even the most picky players… again.
We redefined chorus. There is a new style of chorus that actually sounds RIGHT.
We are proud to announce the all new Seafoam Plus Chorus - True Chorus and ADT with Reverb. It will forever change the way you think about chorus, because we have developed a new type of chorus that until now has only been available in expensive DAWs and in studios. Not only is it tuned for guitar, but there are voices and modes created specifically for bass players including flanging and tremolo. Lastly, this tri-mode chorus pedal offers internal switching for vintage and modern tones, further doubling the amount of sounds you can get.
ADT: THE NEW DEFINITION OF CHORUS. In the Seafoam Plus Chorus you get the automatic doubler that we developed in the revolutionary 30ms Double Tracker. Our ADT chorus is what we call True Chorus, because we create a second and third voice-like singers in a choir. Not only do they sing at different times, they sing at different pitches. True Chorus.