The C GF4 by Sonocurrent is a 12hp [18hp with an optional—but highly useful—C GF4e expander module] group fader and signal distributor. The module has four pairs of input and output jacks—one for each channel—grouped in its bottom half. There is also an input and output jack pair which serves as both CV control over the group level as well as outputting either an offset voltage [when the input is unpatched] or a pass through of the CV from the input jack. All five input jacks have corresponding attenuators surrounding the large group level knob and the inputs are normalled sequentially, meaning any signal patched into a channel input [from 1 to 3] will appear at subsequent inputs.
In use the C GF4 is very straightforward, intuitive, and dead useful, with its most obvious application being to use it as a macro controller over different modulation sources. Individual inputs can be tailored to their sweetspots with the per-channel attenuation, and then adjusted as a group while maintaining their relative levels. A simple concept but not one that is as quick or easy to patch up with separate modules. The C GF4 makes it a breeze to experiment with dynamic, patch-wide sweeps while sticking to the tailored levels of your individual modulation sources.
In a neat trick, the CV input for control over the master level will also pass through its input signal [which can be attenuated by a dedicated control] to the CV out. When left unpatched the C GF4 will output a static voltage at a level that corresponds to the group level control knob setting [from 0 to +5V]. Very handy for creating an additional static control voltage for something downstream in your patch or to achieve an attenuated copy of the input signal for separate but related modulation elsewhere.
The first input also has a +5v normalization that is also cascaded to the following inputs, so with nothing patched in the C GF4 can send up to 4 static offsets out to your system [and as always the global level can be both manually and voltage controlled]. Additionally, the second and fourth outputs can be inverted via manual switches.
The C GF4e expander adds an additional +5V offset controls for channels 1 and 3 as well as toggle switches and voltage controlled muting. The expander’s mutes are triggered and remain active [muted] with any voltage above 2V and pair excellently with LFOs or envelopes for teasing interesting and unexpected rhythmic muting and unmuting of audio or modulation signals.
With all of the possibilities for assuming more control over modulation signals as well as the handy static offsets, the C GF4 really stands out as a utility module. With a solid build and premium feel, the C GF4 is another sneakily handy module from Sonocurrent, whose usefulness and clever design becomes more apparent the longer it is put to use. I find myself reaching for it whether I’m looking for performance control over audio, or macro control over multiple modulation sources, and I continue to discover new ways that it can serve any patch I’m working on.

C GF4
12 HP +12v 95mA -12v 80mA
Price: $195

C GF4e Expander
6 HP +12v 10mA -12v 15mA
Price: $95

sonocurrent.com