"Another one for fans of more subtle 'vintage' effects, the Mellow Yellow is similarly easy to operate, with just speed, depth and level controls.
Note that the level on the MYT is not a mixer control as on the phaser, but a master output control. There's quite a generous amount of extra gain available, so to save pedalboard space, you could even use the MYT as a solo boost, with or without the tremolo effect.
Like we say, the tremolo effect is fairly subtle, but what it does, it does very well. The tremolo shape is very smooth and reminiscent of old Fender amp tremolo; it really sounds great for slow, bluesy rhythm guitar, using lightly overdriven singlecoils and a low depth setting.
With the level turned right up, the extra boost is warm and balanced, and we got great results by adding a hint of tremolo with a very fast speed setting. As the Mad Professor team writes in the user manual, this is almost like having a hint of slapback echo."