Don Morris is an electronic engineer who joined MXR's Engineering Team back in the spring of 1979. This is a short interview about how he worked on the Phase 90 redesign, the insides of the company at that time and his own story.
The Fuzz Face is a distortion guitar pedal designed in London by Arbitrer Electronics Ltd in the autumn of 1966. It produces a characteristic high distorted sound called fuzz.
Ivor Arbiter took the round shaped enclosure idea from a microphone stand and it was the first pedal including a DPDT stomp-switch. The effect became very popular because Jimi Hendrix played it and there were not many distortion pedals around at that time.
The gist of the Fuzz Face remains in the simple circuit that uses eleven components (2 transistors, 4 resistors, 3 caps and 2 pots) and the astonishing tones created with them; delivering a soft asymmetrical clipping that changes to hard clipping in both semi-cycles under the fuzz pot action.
Arbitrer Electronics manufactured the pedal from 1966 to 1975, Dallas Music Industries did a final batch in 1975-77, after that the production stopped. During its lifetime the pedal went through some minor cosmetic but major sonic changes. The fuzz face was re-issued from 1986 to 2000. In 1993 Dunlop took over the production selling the fuzz face in different flavors. Today, both the Dallas Arbiter and Fuzz Face trademarks are owned by Dunlop Manufacturing Inc.
This analysis covers the first Arbitrer Fuzz Face model equipped with PNP germanium transistors from the first releases which is considered the best sounding.
The Dunlop Crybaby is a Wah-Wah pedal released around 1982. The pedal is a copy of the original VOX model made by VOX/Thomas Organ Co in 1970. The effect is basically a band pass filter, it boosts the resonant frequency around 750Hz attenuating above and below harmonics. The rocketing action of the pedal shifts the resonant frequency up and down.
Due to the great success of the pedal, being maybe the most sold guitar pedal of all times, Dunlop produced several versions of the Wah-Wah and signature models adding enclosure customization and small circuit modifications. This study is focused in the first model, the Dunlop Crybaby GCB-95 which is considered to have the classic wah tone.
pedalSHIELD is a programmable Arduino Open Source & Open Hardware guitar pedal made for guitarists, hackers and programmers. Users can program their own effects in C/C++ or download ready effects from the online library.
It is designed to be a platform to learn about digital signal processing, effects, synthesizers and experiment without deep knowledge in electronics or programming.
The Phase 90 is a phaser guitar pedal designed by Keith Barr in 1974. It was the first product sold by MXR with great success. MXR’s contribution to phase-shift effects was the high-quality, small size and reliability of the stompbox, in contrast with previous models that tended to be dodgy, bulky and noisy.
Production ceased when MXR went bankrupt in 1984. Jim Dunlop bought MXR in mid-late 80's, resuming production and adding extra features as LED and external power supply jack.
The old releases by MXR included the so called Script and Block Logo models. Dunlop nowadays offers few variants: Handwired 1974 Vintage model, Custom Shop Script, MXR M-101 Phase 90 and EVH Eddie Van Halen signature model. This study is focused in the first Script Logo model which is considered to perform the best.
The Pro Co Rat is a distortion pedal by Pro Co Sound designed by Scott Burnham and Steve Kiraly in Kalamazoo, Michigan 1978. The original circuit and appearance suffered some changes over the different revisions but the tone remained the same.
Due to the pedal success there are several versions designed by Pro Co like the Juggernaut (1979), R2DU (1984), RAT2 (1988), Turbo RAT (1989), Vintage RAT (1991), BRAT (1997), Deucetone RAT (2002), Juggernaut Bass RAT (2003), You Dirty RAT (2004),'85 Whiteface RAT Reissue (2010).
Although the pedal was originally built as custom-order product in 1978, Pro Co began to mass produce it in 1979. In 2008 production moved to China and is now manufactured by Neutrik for Pro Co Sound.
The M-133 MicroAmp is a clean boost/volume pedal, part of the first Reference Series by MXR released between 1973 and 1984. The original stompbox did not have power-on LED or A/C connector. Jim Dunlop bought the MXR licensing rights and currently manufactures reissues of the classic MXR effect.
The MXR Micro Amp is designed to be a transparent clean volume booster; it does not color or modify the guitar tone. The circuit is in fact an un-distorted redesign of the previous M-104 MXR Distortion+ pedal.
The main application of this pedal is to do louder solos. It can also supply a permanent boost in a long effects chain or cables where signal drop is a problem. Placing it before the amp the signal boost will drive the preamp harder and into more saturation.
The EMG81 is an active humbucker guitar pickup manufactured by EMG Inc. It was developed in 1979 along with the EMG85 and released in 1981. The construction is similar to traditional U-shaped rail pickups with ceramic magnets.
The EMG 81 is commonly used in bridge position, giving high end cut and fluid sustain. It has a three pin header output which makes it easy to replace and mod without iron solder. The EMG81 has two variants:
EMG81 Pickup Specifications:
Resonant Frequency: 2.25 kHz.
Average/Max Output Voltage: 1.25/1.75.
Noise: -91 dBV.
Output Impedance: 10K Ohm.
Current Consumption: 80 uA.
Magnet: Ceramic 56x3x13mm.
Wire: 0,06mm PE.
Core: 54x3x12, 5mm solid steel.
Coil: 4,18 KΩ (one coil), wax potted, approx. 5500-6000 turns, h=7,5mm.
Bobbin: 64x13x9mm (or with tube legs 12,2mm).