Overview:

The phase 90 pedal first released in the early 1970's has been undeniably the most popular and iconic Phase shifter pedal. Released in 1974 by MXR, first with a script design logo, and then changed to the block lettering logo in the later 1970's. This example is from the late 1970's. Used by many of the great guitarists through the years, but most notably by Eddie Van Halen in his early years. Providing a full 90 degree's of phase shift for a dramatic and swirling effect. This pedal was most likely from 1978 based on the POT numbers, 1377821

This breaks out as the first three numbers (137=CTS ), then the year (78), then the week. (21 = may in the 1978 calendar year)

The early MXR pedals also had a foam liner to keep the electronic from touching the case. This foam degraded over time, and in most vintage pedal you will have bits of the foam remaining. It is important to replace with a new foam liner or plastic sheet to protect the electronics from shorting out.

Easy to use. Rate knob for speed of the phase. The script button engages a more vintage phase 90 sound, emulating the classic early script logo models.

Big jet engine swoosh, great distorted or clean.

Solid metal case, and components. Built to last.

Available on the used market and in the Re-issued models by Dunlop with many variations