Clip from El chamuyo - Orquesta Típica Victor 1930
Whole tango on YouTube here
Clip from El once - Carlos Di Sarli 1954
Whole tango on Grooveshark here
(Update: music players don't work on your device or your browser? Try viewing the post in Safari, or reloading the page if you're using Chrome - or click to listen to clips here: El chamuyo - El once)
I hope this will help you understanding syncopation a little better! If you have any questions at all, feel free to ask.