There are now quite a few options for Ubassists when it comes to choose the right string for your preferred sound and playing style. Owen Holt invented the Road Toad Pahoehoe strings (made from polyurethane) to make the super short scale length of the ubass work. These are of course still the original ukulele bass string reference that many use and love.
The Italian string company Aquila Corde now offers three different ukulele bass strings.
Besides the Thundergut string that has been around since 2012 and the Thunder Reds since 2014 they also offer the Thunderblack.
The Thunderblack string has, in my opinion, more similarities to the original Thundergut than the Thunder Reds. I think they feel a bit less sticky then the original Thunderguts but the sound is pretty similar.
If you prefer the look of black strings but want a sound and feel similar to the Thundergut there’s now an alternative available.
In the video below I decided to record some of the same musical exemples used in the Thunder Reds review. This makes it easier to compare the different strings.
Past Reviews
Pahoehoe vs. Aquila Thundergut Part 1 | Part 2
Aquila Thunder Reds Review
Tech specs
Aquila Thunderblack strings
Kala spruce top fretless (2010)
RMI Basswitch IQ/DI in the 10 mOhm setting
Aguilar Tone hammer 500
Aguilar SL-112 cab
AKG C-414 mic
Universal Audio Apollo (upgraded with Thunderbolt card)
iMac with Logic X
Play UBass! 
hello! got a question, did you chance tusk from the ubass to use the thundergut strings, because them are thiner? thanxs
Hi, it’s preferred to change the nut but I didn’t and it worked ok for me. I play pretty soft so the strings don’t move so much in the nut slots!