TubeNet

This site will take a mp3 file of just about any recording, look for patterns of beat, pitch and tempo and make an endless looping rearrangement of the file. It works with instrumentals best, but vocals and even spoken word can be used. I didn't find a tuba track on their page but it is possible to upload files of your choice. They are overloaded right now, so uploading is not possible. (Some files work better than others, and on my computer Safari works much better than my other browser apps.)

This one is quite annoyingly good: http://labs.echonest.com/Uploader/index ... 3AFBEF9FC0