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GFI System Jonassus Drive Pedal

Flexible Dual Overdrive with Multiple Clipping Stages

Written by

Elliot Stent

GFI System may be most renowned for their advanced delay and reverb stompboxes, but the Jonassus Drive is their first dedicated overdrive pedal. Not leaving any of their cutting-edge technology behind, the Jonassus boasts an enviable amount of flexible features, ensuring unparalleled levels of tweakability and ultimately - amazing tones!

GFI Systems Jonassus pedal - A seriously versatile overdrive pedal!

Versatile Control

The Jonassus follows a dual format, giving you a warm and articulate low gain overdrive on one side and a mid to high-gain channel that is more akin to a ballsy, saturated distortion. Each channel has its own gain and volume controls for easy manipulation, and they both share a universal tone control for affecting their treble frequencies.

With an on/off footswitch and a separate switch for flicking between the two drive sides, you can set up the Jonassus more to your own specific needs via the dip-switches on the top of the enclosure. For example, if you only want to use the low gain channel, you can bypass the high-gain side entirely. This means that you can switch between two low-gain channels and set their volume and gain controls differently, giving you essentially two presets. The same can be done for the high-gain channel, if you're more into heavier genres.

3 Clipping Stages 

Another unique feature of the Jonassus is its multiple clipping stages. Denoted by their cyan, amber and violet colours (displayed via the LEDs), these clipping stages affect the character of the drive circuits and their response.

The cyan and amber modes are both diode clipping circuits, which move between asymmetric and symmetric respectively for varying amounts of compression. Cyan offers the most, with a tighter sound that is ideal when used in conjunction with the high-gain side, giving you a focused and dynamic tone for metal playing.

The amber mode has a slightly more open quality, and violet mode which uses an LED clipping stage offers the most unrestrained sound, which is really in its element when used with the low-gain channel.


  • Dual Channel: Low and Med-High gain
  • 3 clipping options for each channel
  • Independent Gain and Volume control for each channel
  • Three operational modes: Low|Low, High|High, and Low|High
  • True Bypass
  • Input impedance: 1M Ohm  
  • Output impedance: 10K Ohm      
  • Current consumption: ~40 mA
  • Weight: 0.6 Kg (1.2 lbs)
  • Dimension: 12 (L) x 7.7 (W) x 5.5 (H) cm
  • Power source requirement: 9VDC (negative center)
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Order now for delivery to you on Thursday, 16 July 2020  

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