Fairfield Circuitry Roger That FM Modulator/Demodulator Pedal Fairfield Circuitry

Inspired by Roger Grant’s idea to mimic loss of fm radio signal through the use of a simplified fm modulator/demodulator scheme. As a young child, I would hide under the table when Roger came around. Later, when I first started in electronics, he gave me a bunch of parts, tools and bench equipment. Controls interfere with demodulation accuracy resulting in familiar yet unexpected signal degradation and noise. Decoherence at its finest.

TUNE:
Like turning the dial on your receiver, the TUNE parameter sweeps through a wide variety of sounds. From subtle artifacts, to extreme textures, noise and distortion. Summmed with CV at T input.

SHIFT:
Shifts the accuracy of tracking the incoming modulated signal. Sometimes acts as a filter. Highly dependent on TUNE.

DRIVE:
Controls the input level, from clean to dirty. Pushing the DRIVE control generates extreme non-linearities from the modulator/demodulator circuit. Affects both the wet and dry signals.

WET:
Amount of wet signal at the output.

DRY:
Amount of dry signal at the output.

R:
Preset range of the TUNE parameter:
1 – normal
2 – extended

F:
Apply voice filter ~(300Hz-3kHz) to wet signal:
0 – filter off
1 – filter on

CONNECTIONS:
IN: 1/4″ Instrument input
OUT: 1/4″ Output
T:1/8″ CV input for TUNE
9V: 2.1mm 9VDC centre-negative tip, >30 mA

NOTES ON INTERACTIVITY:

• The TUNE, SHIFT, DRIVE and RANGE controls are highly interactive.
• The higher the DRIVE, the more artifacts will be generated.
• TUNE is probably the widest, most non-linear, finest control ever included in our products. Micro adjustments here will drastically change the result of the demodulation.
• TUNE and SHIFT are mutually dependant, almost like they are the same control. By tweaking both, it almost seems like there is endless varieties of sounds.
• The RANGE switch shifts the whole palette of possibilities.
• Wet signal path is intentionally out of phase allowing for special interactivity between WET, DRY and FILTER.
• If the original signal is still present on the wet side, adding dry signal will cancel it out leaving only the distortionartifacts.
• If voice filter is activated in these same conditions, the result is a kind of mid-scoop instead of the usual bandpass.

FEATURES AND USES:

• JFET pre-amp
• CV on TUNE
• RFI/EMI approximator
• FM/AM radio quality reducer
• volatile and unpredictable distortion •noise, pop, crackle and squeal generator
• impress your friends

TECHNICALS:

• true bypass
• dimensions 4.7″ x 3.8″ x 1.9″
• input impedance 1MΩ
• output impedance 1kΩ
• power supply 9 – 9.6VDC
• current draw 30mA @ 9.6VDC