Crazy Tube Circuits Golden Ratio

The Crazy Tube Circuits Golden Ratio is a compressor pedal from Greek builder Crazy Tube Circuits. What sets it apart from most pedals in its lane is that it carries more than one compression circuit: the original Golden Ratio Phi, announced in August 2016, put optical and FET compressors in a single stompbox¹², and the V2 revision of October 2021 added a third, OTA, for three all-analog circuits selected at a toggle switch³⁴⁵.

The idea is that each circuit type compresses with a different character, so one pedal covers the ground of several. Delicious Audio described the V2 as updating the company's flagship compressor by shrinking it into a compact case and adding an extra compression mode⁶. GuitarPlayer's reviewer went further, writing that it "offers the tweakability of a studio rack compressor"⁷.

Three compression circuits in one pedal

A toggle switch on the V2 selects between the FET, OTA and OPTO circuits⁵. Each has its own compressed voice and its own ratio range on the Ratio knob¹⁰:

The OTA circuit takes its inspiration from mainstream guitar compressor technology, according to Guitar World, and uses a feed-forward detector circuit, meaning it reads the input signal on its way in. Pedal of the Day called it the most controllable of the three, with a punchy and direct sound¹⁰. The OPTO circuit is built around a hand selected photocell paired with a feed-back detector, which gearnews described as giving a very studio-quality-like smooth attack and release⁴. The FET mode, per GuitarPlayer, "adds its own color to the signal and can be set for super-fast response"⁷.

One thing to know when switching modes: GuitarPlayer's reviewer noted that "the controls reacted differently depending on the mode"⁷, so the same knob positions will not sound the same after a toggle change.

Controls and parallel compression

The control set is the same studio-style layout across the modes: Volume, Blend, Ratio, Attack, Release and Threshold⁴⁹. Separate Attack and Release knobs allow precise control over the dynamics⁶. In the FET and OTA circuits the Attack knob covers 1 ms to 30 ms and Release covers 50 ms to 4 s¹⁰.

The Blend knob sets the mix between the dry, uncompressed signal and the wet, compressed signal, what players commonly call parallel compression¹⁰. Delicious Audio noted it "lets you reintroduce some of the clean signal" for that effect⁶. The Volume knob works like the makeup gain control on a studio compressor, restoring level lost to compression, and it still works with the blend set to no compression, so the pedal can serve as a pure boost⁷.

Inside the pedal there are further adjustments: an internal FET circuit ratio/distortion trimmer, a 9V or 18V switch, and a high/low makeup gain switch⁷. Guitar World also reported an internal switch for choosing the wide 1:1 to 20:1 ratio range⁵. Running the pedal at the 18V setting is said to give increased headroom and enhanced compression characteristics³¹⁰⁶.

Phi versus Phi V2

The original Golden Ratio Phi, announced in August 2016, was a two-circuit design: Guitar Interactive reported that it "features two studio grade compressors, optical and FET, in a single stompbox format"². It was priced at €250 and shipped at the end of August 2016¹.

The Phi V2, announced in October 2021, added the third OTA circuit, moved to a more compact case, and brought the price to €229, or $249 as reported by Guitar Pedal X³⁴⁶⁹. It can also be run on a higher internal voltage than the standard 9V, which gearnews noted gives more headroom and an enhanced compression response from the circuit⁴.

What reviewers said

Reviews of the V2 were positive across the board. GuitarPlayer's verdict was blunt¹⁰⁹⁷:

GuitarPlayer, 2022⁷

Pedal of the Day was equally impressed by how much was packed into the enclosure: "Not sure if there's ever been this many compression options and incredible tones packed into a unit this size"¹⁰. Delicious Audio highlighted the pedal's "superb low-noise floor performance and full frequency response making it ideal for guitar, bass and virtually every instrument either on studio or stage"⁶.

The one recurring criticism came from Guitar Pedal X's Stefan Karlsson in 2026, who called the V2 "super smart" and said it delivers everything essential, though he would have liked a tone control⁹.

Videos

Click to load

Click to load

Click to load

Questions