Gyraf G24 Passive/Aggressive Cadmium compressor

Unique passive stereo compressor with dual stereo sidechain, continuously variable between L/R to M/S and Feedforward to Feedback modes.


The  Gyraf Audio G24 is a unique passive stereo compressor with an intricate control system, designed to provide gentle control of an otherwise perfectly balanced mix.
The Gyraf Audio G24 uses a fully passive audio path with only a metal film resistor, a transformer and a photo resistor for each channel. This minimal setup ensures no degradation of the signal.
In contrast, the G24 or Gyratec XXIV as it is known, boasts a huge range of controls. It starts with two stereo sidechains working simultaneously, one to grab short transients while the other one can be used to slowly ride gain. a Control knob then lets you find the ideal balance between the two sidechains, in effect letting you blend two compressors.
Unlike most compressors, the G24 is in reality two M/S compressors with a fully variable control knob which when the “Elliptic” control is centred works as a stereo compressor. Furthermore the Gyratec XXIV not only offers a choice between FeedForward and FeedBack modes but it also lets you choose any combination in between.
The sidechain signal is mono compatible to ensure summing for M/S thanks to a repurposed signal processor which splits the signal phased to +90 and -90 degrees and ensures a summing of +3dB in the Mid and side components instead of +6dB in the mono signal.
Gyraf Audio G24 Passive/Aggressive Compressor Main Features:

Completely passive signal path
Dual sidechain, which effectively means there are two available compressors that act upon the source.
Continuously variable L/R to M/S
Continuously variable compression characteristic between FeedForward and FeedBack

A Message From Gyraf Audio:
As you may or may not know, optical compressors can no longer be sold in the EU or California. No execptions. The industry (of which I’m part) is trying to ignore this away, and the G24 was conceived as a protest against an environmental legislation that allows massive amounts of Cadmium for batteries, yet bans an entire division of audio processing in order to save the environment from the very-small amounts of Cd in these OptoCouplers. All very technical and sad, don’t get me started… The “Aggressive” part of the unit’s name comes not from it’s way of behaving, but from my aim of stirring up the soup to get some sort of focus on the unbearable situation for real pro audio because of these rules…
What it sums up to is the fact that the G24 is not really for sale, as we can’t sell you it’s heart – the CdS cell. We will need to remain legal owners of that central part, and only only lease it to you temporarily.
That is; You want one, we will need you to sign an agreement that we own the heart, and that at some time (if ever), when we have found a suitable replacement material and shipped you a module containing a new and legal part, that you will open the unit, plug the new one in, and send the old one home to us. We have arranged a disposal ritual as a small yellow-orange dot on a piece of pottery from a local artist – this is one of the legal uses of cadmium. So prepare for some paperwork if you’re in the EU or California like 95% of our customers.
G24 is M/S, two sets of controls – and passive. There is an option to buffer output to ensure drive capability for difficult loads if such are encountered. G21 anyone? Bypass is as always full-relay, and G24 has a output trim function for easing comparison between direct and processed material.


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