Fairfield Circuitry 20% More Slew Limiting Distortion Pedal

Fairfield Circuitry 20% More Slew Limiting Distortion Pedal

Explorations around a schematic found among old papers of mysterious origin, suspiciously similar to a datasheet sq/tri oscillator. All that was needed was to connect the dots.

A slew limiter smoothes out how quickly incoming voltage can change, limiting it to a fixed v/sec. slope. since time and frequency are intrinsically linked, this acts as a steep, somewhat distorted low pass filter.

When it resonates (FEED), these fixed slopes become triangle wave oscillations, giving 20% more its unique sound. Your input signal can overwhelm this oscillation, making for pseudo-wavefolding and synthetic distortion artifacts.

This topology can result in quite a dark sound when SLEW is low, as there will not be much harmonic content present beyond the cutoff frequency. You can use BLEND to mix in a square wave signal that can help bring back some higher harmonics.

Controls

• INPUT 'mu amp' jfet preamp, lots of gain
  
• BLEND  mixes in a square wave/ sub-octave copy of the signal
  
• VOLUME  output volume, gets very loud
  
• SLEW  slew limiter frequency
  
• FEED  slew limiter feedback
  
• LPG  low pass filter
  
• D - OCTAVE DOWN clock division of the blended square wave, -1 or -2 oct
  
• U - OCTAVE UP analog octave up, full wave rectifier
  
• E - ENVELOPE DESTINATION routing of the internal envelope, either added to the (L)PG or (F)EED controls

Specifications

• Dimensions: 4. 7" X 3.8" X 1.9"
  
• CV Input Range: 0 - 5v normal ; 0 - 8v max 9VDC
  
• Power Supply: 20 mA@ 9.6 VDC

Please feel free to reach out to our knowledgeable sales staff with any additional questions!