I have been a huge fan of MXR Phase 90's for years. This pedal had been on my pedalboard since the early 90's and I never thought I would use any other phaser until I got a Phase 100. Though I always loved the sound of the Phase 90 I always wanted the added options of the Phase 100. In 2014, the crew over at Dunlop debuted a limited custom shop run that has even more options than the Phase 100 calling it the Phase 99! It basically combining two phase circuits into a single Phase 90-sized housing!
The MXR Phase 99 has a separate rate control for each circuit that allows you to create intense complex phasing, and a "Vintage" switch that toggles between modern and vintage style phasing. Also, the Phase 99 features a P/S switch to toggle signal flow between the circuits from series to parallel, and a sync switch to synchronize the rate of each phase circuit. Peep the video I shot for it and listen to the wild phasing I get going with this pedal. Having been a player that never used two phasers at once, I was pretty blown away with the sounds I was getting and I may have to retire my Phase 100's for the Phase 99!