Vahlbruch FX 6-PHI-4 Phaser

The  Vahlbruch FX 6-PHI-4 is a high-end, hand-made, analog multi-stage phase shifter manufactured by a German builder on the rise.

The circuit is the company’s take on the classic JFET phasing effect and uses a matched set of 4 or even 6 new-old-stock 2N5952 transistors. Unlike the vintage unit that put the phaser on the map, the 6-PHI-4 is quite tweakable, incredibly quiet and very transparent.

A toggle switch offers 4 and 6 stage phasing, while the three knobs deal with Intensity, Volume, and Speed, which can be visually tracked by looking at the pulsating LED light.

Vahlbruch puts a lot of emphasis on their proprietary switching technology “MagTraB,” which is allegedly indestructible and completely silent.

Wondering how this phaser sounds? Here’s the first video of it.

Vahlbruch FX 6-PHI-4 Phaser, Builder’s Notes

Vahlbruch “6-PHI-4” analog multi stage phase shifter, phaser pedal

The “6-PHI-4” pedal is the latest version of my interpretation of the famous analog JFET phasing which we all love. Its everything you would expect from a classic phaser pedal – but on steroids!
With a carefully matched set of 4 or even 6 new-old-stock 2N5952 transistors, the “6-PHI-4” provides everything from your favorite vintage 4-stage script logo phasing to 6-stage phase swirl with even more depth and vibe, expanding the tonal range into the Univibe and Leslie territory. Because of the hand-selection process and tight matching of the NOS transistors an especially deep and homogenous modulation is achieved, at the same time with a super low level of background noise. Its a very transparent sounding pedal delivering an organic tone you will love.

Unlike most vintage pedals the Vahlbruch “6-PHI-4” has plenty of control ability. The “Speed” and “Intensity” knobs offer a wide range of different phasing sounds. The output volume can be adjusted using the “Volume” control. An extra LED indicates the modulation rate.

This pedal is equipped with our unique Magnetic Transducer Button “MagTraB” switching technology:
Inside the button a magnet is integrated which position is measured by a sensor on the circuit board. If the button is now moved, e.g. if it is pressed downwards, the position of the magnet will also change. The sensor measures this change without any mechanical contact to the button and the information is send via a micro-controller to a gold-plated relay, which then does the actual audio signal switching.

The advantages of “MagTraB” footswitches:
MapTraB buttons are as good as indestructible! “MagTraB” delivers an almost infinite number of switching cycles – many, many millions!
No annoying, mechanical switch clicks! Instead, the “MagTraB” push-buttons switch very smooth and silently!
You can choose if the pedal powers up in “on” or “bypass” state.

To change the state:
Step 1: Unplug the power supply cable.
Step 2: Hold down on/off “MagTraB” button.
Step 3: Plug in again the power supply cable.
Step 4: Release on/off “MagTraB”” button.
DONE! The next time your pedal powers up it will automatically start in the other state.


Unique Magnetic Transducer Buttom “MagTraB” switching technology
Toggle switch to select 4 or even 6 stage phasing sounds.
Hand-selected NOS transistors for a deep and homogenous modulation curve
Super low noise
“Volume” knob controls the pedal volume and can also boost the output
“Speed” regulates the modulation rate
“Depth” can be used to adjust the depth of the modulation
Continously pulsating LED indicates the speed of modulation
Input impedance: 1M Ohms
Output impedance: 100 Ohms
Current consumption: 40mA
This pedal requires an external regulated 9V power supply (not included), polarity: positiv@ring / negative@tip
Dimensions: 115mm x 70mm x 48mm
Weight: 240g
Handmade in Germany