Metasonix RK5 Dual Low Pass Gate

Older than vintage – With the RK5 Dual Low Pass Gate, it is possible to experience music history that never took place. The module answers the question of what a low-pass gate from the 1950s would have sounded like. – This type of circuitry was not developed until the 70s. The LPGs contained in the RK5 consist of a simple Sallen-Key filter with audio input and output plus a control voltage input. The tube used is a dual triode, type 17JK8. In terms of sound, the two low-pass gates of the RK5 differ. Generally speaking, the module offers crisp and warm, gently distorted results with a rather long decay. – The perfect partner for creating unique, somewhat dirty Buchla Bongos and other percussive sounds.

Conceptually, a low-pass gate made in the 1950s would have consisted of a cathode follower, two linear optocouplers featuring incandescent lamps and some capacitators as well as resistors. – A fairly simple circuit design, yet it was never done.  With the RK5, Eric Barbour now closes this gap. The module comes equipped with two low-pass gates. Each channel features an audio input, a control voltage input and an audio output. The dual triode, type 17JK8, is a NOS leftover. Back in the day, it was mainly used for building FM radios. In terms of optocouplers, Mr. Barbour deviates slightly from the ideal of the 1950s: Instead of components with incandescent lamps, he uses linear, LED-based Silonex optocouplers. – A good decision, as miniature lightbulbs have a much shorter live span than light-emitting diodes. Due to dissimilarities of the two triodes contained in the tube and rather high tolerance values of the optocouplers, the RK5’s low-pass gates vary in sound. The results from module to module slightly differ as well, meaning each RK5 is a unique piece of gear.