“The MXR Model 142 was manufactured from approximately 1978 to 1984 when MXR was acquired by Dunlop. Production stopped around 1984 prior to the sale to Dunlop. The 142 was never reissued by Dunlop as other classic MXR pedals were.”
“Although it is the same mustard color as the ubiquitous Distortion +, the circuit design is completely different and although they share the “distortion” moniker they sound nothing alike. The 142 was designed to emulate an over driven amp pushing a 4-12 cabinet.”
“The resonance control provides a signal with a 55hz centered hump or pass-band that could be added to the basic over driven sound. 55hz is the resonant frequency of the old Celestion G12-M speakers loaded in many Marshall cabinets.”
Great read. Perhaps true? No idea of the original source.
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