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Metasonix R51


Vacuum-Tube Voltage-Controllable Distortion/VCA

The R-51 is unique and never before available in any form. It uses two remote-cutoff pentodes, type 26A6. Two CV inputs are available for controlling circuit distortion from less than 2% up to more than 40% (varies with individual tubes). Two CV inputs also allow use of the R-51 as a conventional synthesizer VCA, with gain variable from less than -75dB to +5dB (typical). Both distortion and VCA features can be used simultaneously. This allows true vacuum-tube asymmetrical soft clipping to be applied to any waveform. With suitable CV processing, the R-51 can be configured as a true “variable mu” limiter or expander.


  • +/-12V Doepfer-style power connector
  • alpha rk12l potentiometers
  • kobiconn vertical-mount 3.5mm jacks
  • Current Consumption: 150mA
  • Panel size: 22HP

Other modules by Metasonix | R-52 | R-53 | R-54 Mk2 | R-56 Reverb | R-57 Dual VCA (last one – once it’s gone it’s gone!) | R-60 | RK1 Noisedrum | RK2 XS-VCA