m277 / Tube VCA


m/277 Stereo High-Voltage Tube VCA / Overdrive / Preamp module for Euro Modular Form Factor



Before the jet-age transistor era with household names like Bob & Don was another, often overlooked era of analog synthesis made popular by folks like Laurens & Raymond. The “pre-war” technology’s sound has luminous qualities, quirks & artifacts befitting the high voltage glowing elements of glass which produce it.

With the vision of delivering this classic technology for analog audio synthesis to a form-factor designed for solid state bug sized chips of the 1960’s Trogotronic issued m/277 high-gain Vacuum Tube Stereo VCA without sonic compromise. Tube Harmonics, Bass-Heavy Compression & Stereo Imaging are applied with 2 Discrete High-Voltage VCA Circuits. The new v4 m/277 is entirely redesigned delivering higher voltage, dead-quiet crystalline performance directly from your euro-rack power supply.

m/277 Tube Analog VCA delivers:

  • 2 Tube VCAs
  • 2 CV Amplitude Inputs with Attenuator Knobs (1 per channel)
  • 2 CV Drive Inputs with Attenuator Knobs (1 per channel)
  • 1 CV Master Panning Input & Manual Knob Control 
  • 1 CV Master Panning-Drive Input & Manual Knob Control
  • Ample gain for use as a Stereo External Input Preamplifier
  • Zero to +5 volt CV-Range compatible w/most LFOs, Envelopes etc.
  • Warm Tube-Harmonics
  • Compression with Low-End Enhancement 
  • Compelling Stereo Imaging
  • Pannable Stereo High-Gain Tube-Overdrive Effect
  • Warms cold digital effects & low-voltage solid-state signals
  • Optional High-Current Power Supply = low impact on your rack’s “built-in” supply
  • 4 CV Lamps: 2 Blue (Amplitude A & B) / 2 Red (Drive A & B) 
  • 2 Psvane Max. Gain, Twin-Triode Vacuum Tube run at high-voltage
  • Plug & Play Compatible w/ Alternate Tubes for Auxiliary Sonic Profiles 

Demand on the +12v tap is 720mA for the first 10 seconds of warm up. Too much demand on rack’s available current? Being of a thrifty subhuman stock we made sure to continue offering an optional auxiliary supply which takes ALL current demand off of your rack’s +12v rail rendering a ZEROmA load on this rail when implemented!

Use at the end of a patch: Rich tube harmonics & brawny compressed low-end add warmth to your cold digital effects / signals while reinforcing plastic sounding low voltage analog sound.

Use to portray mono signals as vast stereo audio panoramas: The 2 discrete channels run in parallel add depth to mono signals with organic stereo imaging built into the circuit. The same mono signal can be dynamically panned & effected via the Pan CV Input & corresponding knob control.

Use as a stereo overdrive effect: The Drive CV inputs are discrete (1 for each channel independent of the other) enabling the module to be used as 2 separate CV controlled tube overdrive effects. The Pan Drive CV Input / Control makes the creation of dynamically panning stereo overdrive effects via CV Drive a cinch.

Use as external input stereo preamplifier: Gain afforded by the m/277 is more than adequate to make even the tiny signal of a guitar or microphone patched comparable with modular line levels.

Video Samples (Old Version):

  • Euro-Format
  • 15HP
  • Depth 2.25″ 
  • +12v rail Startup peak current 720ma; avg. 390ma  (0mA w/optional Aux. Supply)
  • -12v rail peak current 3ma
  • 12vDC Aux. Power Supply: Optional


All Trogotronic instruments come complete with pretty much everything needed to “plug & play”. Still, herein are replacement parts should ever something go missing (plus a few extra options should ever such a fancy strike).