5-string · One-piece body and neck, integrally layered exoskeleton with Arium core
Aristides' original bass: a 5-string built from Arium, praised for its clarity in the low register and the instrument the flagship S/B series was later designed to surpass. Arium is Aristides' proprietary non-wood composite: an integrally-layered exoskeleton around a resonant core, formed as a single piece with the neck, which the maker credits for the material's stability and even response across the board. Discontinued and superseded by the S/B5 — Aristides no longer publishes a spec sheet or price for it, so only the string count and construction are recorded here. Played by Fernanda Lira of Crypta, an Aristides artist since 2012. Handbuilt in the Netherlands.
| Construction | One-piece body and neck, integrally layered exoskeleton with Arium core |
| Strings | 5 |
| Body | Arium (proprietary non-wood composite) |
| Neck | Arium (one piece with the body) |
| Fingerboard | Richlite (black or light) |
| Made In | Netherlands |
Artists documented playing the Aristides Instruments 050: Fernanda Lira.