RARE TRANSITIONAL HYBRID MODEL – EARLY BLOCK LOGO HOUSING WITH ORIGINAL SCRIPT-ERA CIRCUIT AND SCRIPT MXR ENGRAVING ON THE BACKPLATE. 100% ORIGINAL UNTOUCHED

A particularly interesting vintage MXR Phase 90, dating from approximately 1977, combining the later Block Logo exterior with the earlier Script Logo circuit architecture.

This is not simply a standard vintage Block Logo Phase 90. Its originality and transitional features make it a particularly appealing example for collectors of early MXR pedals.

Best Of Both Worlds : A genuine hybrid of two eras

This Phase 90 brings together three distinctive features:

• Early Block Logo on the front: the familiar orange enclosure with the bold MXR Block Logo.
• Original Script-era electronics: the factory circuit board and component layout match the early Script Logo Phase 90 circuit architecture, consistent with the 1976 examples documented in comparative photographs of several original vintage boards.
• Script MXR engraving on the rear cover: the underside retains the elegant, engraved Script-style MXR logo, providing a striking detail that links this pedal to the earlier generation.

Together, these features make it a fascinating transitional example from the period when MXR moved from Script Logo to Block Logo production.

Original electronics – never modified

The pedal retains its original vintage circuit board, original factory wiring and period components.

• Six Texas Instruments UA741CP operational amplifiers.
• Original CTS potentiometer marked 1377709.
• CTS date code corresponding to the 9th week of 1977.
• Internal factory marking: 137196.
• PCB marking: 90B.
• Original resistor mounted on the reverse of the circuit board.
• Original solder joints and components, with no replacements or circuit modifications.

The circuit has been visually compared with photographs of several early Script Logo Phase 90 circuit boards published online. The component layout and circuit architecture are consistent with the 1976 Script-era version.

The CTS potentiometer date code establishes that assembly took place no earlier than the 9th week of 1977, making this a compelling example of the transitional period between the Script and Block Logo generations.

Fully working – authentic vintage character

The pedal is fully functional and works perfectly.

It delivers the classic analog phasing effect that made the MXR Phase 90 one of the most recognizable effects in guitar history.

Original vintage construction, early circuit architecture and distinctive transitional styling make this an excellent addition to a serious vintage pedal collection.

Condition and originality

The pedal is in authentic vintage condition, with age-related wear consistent with its age.

The original circuit board, components and wiring have been retained. Residue from the original internal protective foam is visible in places on the circuit board; this is the result of the original foam deteriorating over time, not evidence of a circuit modification.

Please examine all photographs carefully, as they form part of the description and document the pedal's distinctive features.

Specifications

• Manufacturer: MXR
• Model: Phase 90
• Approximate date: 1977
• Origin: USA
• Front logo: Block Logo
• Rear cover: Engraved Script-style MXR logo
• Circuit: Original early Script-era architecture
• Op-amps: Six Texas Instruments UA741CP
• Power: 9V battery
• LED: None, as per the original vintage design
• Operating condition: Fully functional
• Modifications: None reported; original components and solder joints retained

An unusual piece of MXR history

For collectors looking beyond the standard Script Logo and later Block Logo versions, this Phase 90 offers a distinctive combination of original features from both eras.

The Block Logo front, Script-style engraved rear cover and original Script-era circuit architecture make it a compelling vintage MXR transitional model.

A genuine vintage Phase 90 with an unusual hybrid identity, original electronics and fully working condition.