ST Modular – FAY (Fader/VCA/Decay Envelope) 4hp FR4 panel & pcb set

Original price was: £10.50.Current price is: £5.99. (exc VAT)


ST Modular website


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This listing is for an unpopulated pcb & panel set only.

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Fay combines three functional units in a tiny 4HP module. It consists of a Fader, a VCA and a Decay Envelope.  

If you insert two audio or CV sources into the jacks IN1 and IN2, you may fade between both sources manually using the potentiometer on top. This way you can either mix two waveforms or switch between them.

The signal is directly routed to the VCA. Here you can control the volume or amplitude of the audio or CV signal either manually or via control voltage using the ENV jack.

If there is no cable patched to ENV you will be able to control the VCA with the internal decay envelope. Simply insert a trigger signal into the TRIG jack and use the potentiometer below the LED to control the decay length. The LED indicates the current state of voltage.


  • Manual fader/mixer/switch
  • Voltage controlled amplifier
  • Decay envelope
  • Suitable for audio and CV signals
  • Full control over volume
  • CV attenuator
  • LED indication
  • VCA control with internal or external CV
  • Wrong polarity protection
  • 3U Eurorack module, 4 HP wide
  • Power consumption: 25 mA at +12 V and 10 mA at -12 V

The module consists of three boards:

  • Front PCB Panel
  • Control PCB for LEDs, potentiometers and jacks
  • Main PCB 


Additional information

Weight 30 g
Dimensions 128.5 × 20 × 4 mm

Synthesiser parts/components