This is a vintage 1977 MXR Phase 90 phaser pedal. Since its introduction in the early seventies, the MXR Phase 90 has always been regarded as one of the classic analog phaser pedals and has been used by greats like Jimmy Page and Eddie Van Halen. This particular example is in excellent vintage condition and perfect working condition.
This early block logo variety is in nice original condition. While it is not the earliest script logo version, it does feature the script logo bottom plate. It even has the original battery.
From the slowly shifting tonality at one extreme to the fast bubbling at the other, this is organic phasing that seems an integral part of the guitar sound rather than something slapped on top of it. Eddie Van Halen used these on his solos for the treble boost quality of the Phase 90, and a slight tonal shift in that direction as part of the effect is apparent when kicking the pedal in, but it’s the silky quality of the phasing that is the real deal here. It can nicely replicate simple UniVibe sounds rather easily, and is actually quite versatile for a one-knob effects pedal.