We always like to see vintage pedals in here and this is definitely one of the holy grails. The Shin-ei Uni-Vibe is the original uni-vibe pedal which has inspired clones for decades since its inception as a portable device to emulate a Leslie spinning speaker.
This pedal was in for basic servicing but the important goal was to build a replacement expression pedal since the main unit does not have a Speed knob or a bypass switch rendering the main unit useless. Our replacement expression pedal unit uses a custom 5-pin DIN cable to connect to the main unit so the rate can be adjusted while playing.
The interesting part of this project was that in order to copy the original expression pedal we needed to install a bypass switch in the heel. Most people are familiar with a wah pedal which is activated by pressing down firmly with your toes. While this works great for a wah pedal it can sound bizarre on a univibe as you would need to turn the rate to full speed (toe down) in the process of hitting the switch. By placing the bypass switch in the heel (rocked back) position it allows for a seamless transition from the slowest setting to the bypassed tone with almost no effort.
This project was a custom build but we are always able to recreate similar expression pedals as a direct replacement for the original Uni-Vibe expression pedal.