Univox SR55 For Sale. This is one of the earlier beatboxes, with classic analog drum machine sounds similar to those of the beloved Roland CR-78 Compu-Rhythm, but with a little more balls. There are a variety of cheesy preset patterns to choose from. The foxtrot and swing patterns have quite a few variations, cause that's of course why drum machines were invented in the first place. Yeah. Really though, this vintage 1970s SR-55 beatbox is lots of fun and sounds great.