The F-Stop brings two effects found in vintage American tube amplifiers into one pedal. The combination of a tube driven spring reverb with pulsating "bias" tremolo was first introduced in the early 1960s and has become a standard sound for guitar players and other instrumentalists ever since.
The F-Stop has been designed to bring classic tube amplifier effects into a small package that runs off of a 9VDC pedal power supply. Internally, the F-Stop has 18v of headroom so it can live as comfortably at the end of your signal chain as it does at the beginning. The spring portion of the pedal is digital, but the guitar signal path and tremolo circuit is 100% analog.
The sound of bias tremolo and spring reverb is unmistakable, and the F-Stop uses modern electronics to achieve an authentic recreation of these effects with similar circuit topography as found in tube amplifiers.