The Catalinbread Pareidolia Harmonic Mesmerizer is based around the 1961 Fender Twin Amp... The Vibrato in this amp was actually more than Tremolo. I am not sure exactly what the effect should be called. Vibrato? Tremolo? Modulated dual filter? Phasor? Leo called it “vibrato” which isn’t technically correct. It is an amazing sound though!! Truly the “sinewave” Brownface tremolo sound, folks are looking for. We used this as the starting point adding a lot more range of speeds and much more depth.
We're convinced that once you turn on the Harmonic Mesmerizer, you'll have a tough time turning it off. Here's a fantastic clip to wet your whistle, showing the Pareidolia's range both clean, and through a cranked amp.