i recently got the monotribe, and it's sweet! it's my first real synth, and i'm happy with the variety of sounds you can get out of it. so i didn't know much about the whole audio pulse sync thing, so after doing some reading i found out that it's just roughly a 5v pulse of sound. ok so controlling it's tempo via the sp505, you probably could use any sp that has a solid sequencer. but basically all you need to do is sample the audio pulse from the monotribe by hooking up a cable from the sync out on the monotribe to the sample in on the sp. once sampled, take that sound and enter it in to a sequence; i did 1/8th notes at roughly 100bpm. once you got the sound sequenced and playing at a constant hit, just use the headphone out jack to plug a cable into the sync in on the monotribe. now play the sequence on the sp then play whatever sequence you have on the monotribe, you should be able to accurately adjust its tempo. one consideration is that the sampled pulse sound needs to be loud enough for the monotribe to hear, so i had to turn up the volume on the sp. unfortunately that clicking sound will always be heard if you are also listening through the sp, but at least it's a different way to control the tempo on the monotribe

i think is something similar to the cv gate i have on the korg ms20 (1978 synth): at the time there still wasn't midi on all synth so they controlled synths via volts. i experimented that loud sine waves are very well accepted by the cv gate other than noisy sample (for examples). so a sequenced groovebox is very cool for that aim, for example. or a sampler like the 505 (with clear synth samples) is maybe suitable. the more is clear/loud the best is to contol the monotribe maybe.