This is how your UBass should be tuned.
The U-bass also called Rubber Bass, Travel Bass or Bass Uke is a relatively new instrument that needs an amplifier to be heard. The sound is then much like a double bass and can be used for the same reason – this is really a kind of contrabass. The tuning is the same as for a BassGuitar. E A D G. Press play, listen and start tune! Good luck!
4 String UBass Tuning
(Start from your top string)
Cello – Online Tuner