A devices that converts between different types of synchronization signals. The most typical type of sync converter is one that converts MIDI Clock messages to a DIN sync signal. This allows older drum machines that do not have MIDI interfaces to be synchronized with a sequencer or DAW. Some devices also convert the other way, so that the drum machine can be the timing source for the rest of the setup.
Another type of sync conversion is found built into some MIDI interfaces. It converts SMPTE time code into MIDI Time Code and MIDI clock messages. This is used when recording to multitrack tape; one track of the tape is "striped" with SMPTE time code that is played back into the converter circuit during subsequent recording. This provides synchronization with the tape, and it serves to cue a sequencer to be at the same location as the tape during playback.