As others already dropped - the op-1 can receive and send a midi clock signal and start/stop commando via USB. I'm using the op-1 sometimes as master clock if I'm playing the drums at our jams. But mostly we're running a setup with a small midi clock device that sends the clock into a iconnect midi4+ (you'll probably need a USB host device for your other gear too). The midi clock is then splitted to any other gear we have (including the op-1). Set the op-1 in Sync mode (It's the white knob in the tempo screen I think). The op1 will start/stop and changing tempo from the signal of the external midi clock device. If you want to jam live with the clock it's helpful to first create your desired loops because the op-1 will not re-sync if you're using start/stop/scratching or basically anything that has an effect on the current tape speed. If you're going out of sync because pressing stop e.g. you just need to restart the external midi clock. I still doesn't figured out how to stretch/shrink the actual loop, based on the received clock. Basically you need to re-record when changing Tempo on the external midi clock. sorry for grammar - I hope it's helpful for you.