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Advanced Parallel Blender

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About the Product

Duophony is our take on the lowly 'parallel blender' pedal. We took the basic concept of blending two effects together to the next level by integrating the classic signal blender functionalities with modern features and intuitive user interface. The result is a solid blending machine, optimized to help you unleash the unexplored ideas of parallel blending and discover new ways of sculpting limitless soundscape!

Full stereo signal paths

Duophony features full stereo signal paths throughout. TRS jacks supports both mono and stereo connections for the inputs and effect loops, while dedicated Left and Right TS jacks are provided for the outputs.


16 presets, readily accessible via the two on-board footswitches, external aux-switches, and MIDI.

Hassle-free blending with presets

Up to 38 on-board algorithms - more may be made accessible via the SymmLab editor.

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Photo Gallery

Expressive Flexibility 

Adjust blending ratio or the Dry signal level at will with an expression pedal!

Fully configurable Heel and Toe values for flexible expressive control. Expression pedals with 10 KOhm pot value are supported.


Modulated Blending

A unique feature that Duophony has is “Modulated Blending”, the ability to modulate the blending action with an internal LFO. When modulation is activated, an internal LFO will produce a waveform whose shape maps directly to the blend ratio. Modulation speed can be controlled via expression pedal, tap-tempo, or MIDI clock.

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Comprehensive external control ​​


  • Expression Pedal - with adjustable heel and toe values.

  • Aux Switches - accepts up to 3 external switches for versatile control (tap-tempo, bank up/down, etc).

  • MIDI In - nearly all features and functionalities of the pedal are opened to MIDI access, including MIDI clock. 

Purity and Precision


100% analog signal paths, coupled with high headroom and low-noise design preserve your signals and tone.

Precise digital control provides seamless user interface and ease of use.


Key Features

  • Input impedances : 1 MOhm.

  • Output impedances : 500 Ohm.

  • Current draw : ~150 mA.

  • Input / Sends / Returns jacks : 1/4 inch TRS.

  • Output jacks : 1/4 inch TS.

  • Expression / Aux input jack: 1/4 inch TRS.

  • MIDI Input connector: 1/8 inch TRS.

  • USB connector : Type C

  • Dimension : 9.7 x 12 cm (3.8 x 4.7 inch)

  • Power requirement : 9VDC / 150mA, negative-center plug (Power supply is not included). 

  • True stereo on all (inputs, outputs, & FX loops) signal paths.

  • Parallel or Series routing modes.

  • 3 parallel blend modes : XY mix, Y plus [X], and X plus [Y].

  • 16 Presets.

  • Fully adjustable dry signal level.

  • Phase invert function on loop X.

  • Individual gain control for each loop.

  • Bypass function with or without trails.

  • Expression pedal and Aux switches control input.

  • MIDI input.

  • Full-featured modulation engine.

Demo Videos

They said I took it too far, so I went further.

They said I took it too far, so I went further.

I've been getting some comments saying I'm not doing the right thing with my harp. Today, I'm going to continue to do the wrong thing, but see how far I can go with it. Thanks to GFI System for sending me the Duophony! ⤑ *the rest of the pedals used in this video are listed below* Here’a a deeper dive on the Duophony (on guitar) ⤑ Curious about how my harp works? ⤑ Want to support the channel? Join us on Patreon! ⤑ All music from this video is on my bandcamp! ⤑ Check out Samantha Ballard's channel! ⤑ Pedals used in this video (I have videos on my channel for most of these!): ⤑ GFI System Skylar: ⤑ Vongon Polyphrase: ⤑ Vongon Paragraphs: ⤑ Chase Bliss Gen Loss MKII: ⤑ JHS Artificial Blonde: ⤑ JHS 3 Series Octave Reverb: ⤑ Spaceman Effects Delta II: ⤑ Red Panda Bitmap 2: ⤑ OBNE BL-44: ⤑ OBNE Dark Star: ⤑ OBNE Expression Ramper: ⤑ Fairfield Circuitry Randy's Revenge: ⤑ CopperSound Pedals Telegraph V2: ⤑ Bananana Effects Tararira: ♡ ♡ ♡ ♡
The BEST Parallel Effects Blender! GFI System Duophony | Secret Weapons Demo & Review

The BEST Parallel Effects Blender! GFI System Duophony | Secret Weapons Demo & Review

Confession: Ive been secretly using the Duophony on this page for over a month now. It's become the essential core of my Digital Amp rig, allowing me to blend between the UA Ruby and Dream without compromising on the stereo image of either. But with presets, MIDI, flexible routing, and an LFO (yeah), it'll do so much more. Get 7% off your first year of DistroKid and support the channel with the link below: Support me on PATREON and get exclusive access to the music in this video, behind the scenes content, and my Discord: Signal Path: Bondi 2026 Benson Boost Black Mass 1312 Bondi Del Mar Benson Preamp Strymon Timeline Strymon Bigsky Strymon Flint UA Ruby, Dream Strymon Dig Neunaber Illumine Hologram Microcosm Meris LVX Timecodes: 00:00 Intro Song 03:09 Review 09:59 XY Balance & Parallel Amps 05:01 Blending Modes & Wet/Dry/Wet 24:37 LFO Modulation & Ambient Soundscpaing Recorded in Universal Audio LUNA Thank you for watching. If you like what you heard here, consider following me on Instagram for more music, gear, and a look behind the scenes of producing videos like this. Below is a list of the gear I use to make these videos. They are affiliate links and help support the channel if you purchase anything. - VIDEO GEAR - Sony a7sii - Lenses - Lights - Monitor - Tripod - - AUDIO - Shure SM7B - Soyuz Launcher -

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