Fairfield Circuitry Roger That - FM Modulator/Demodulator

Fairfield Circuitry

Inspired by Roger Grant's idea to mimic the 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. Summed 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 distortion artifacts.

• If voice filter is activated in these same conditions, the result is a kind of mid-scoop instead of the usual bandpass.

• 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

• 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