Augmenting the Double Bass

A project by instrument builder Halldór Úlfarsson and double bassist and programmer Adam Pultz Melbye. A traditional double bass is modified with a built-in speaker, individual string pickups and onboard signal processing to create an instrument whose very expressive resonant properties rely on feedback principles

The FAAB (Feedback-Actuated Augmented Bass) is part of an ongoing research into double bass resonance and how analogue and digital augmentations of the instrument shape and alter fundamental properties of the instrument.

The collaboration with Halldór combines his experience from the development of the halldorophone, a cello-like feedback instrument, with my use of extended instrumental techniques, feedback tactics and programming to create an instrument that may look like a double bass but behaves more like an autonomous agent with the temper of a hippopotamus (hippopotami are very aggressive and unpredictable animals). The implementation of onboard signal processing in the shape of the Bela board ( allows us to further shape the behaviour of the instrument. Currently, a variety of machine listening and control signal tactics are being investigated, with the intention of ultimately let spectral shaping rely on the instruments response to environmental as well as internal states.

While responding very favourably to the use of extended techniques designed to provoke resonance-buildup, the instrument, although physically deterministic, is phenomenologically often delightfully unpredictable. As such, the human performer is ever reminded that their place in the world is in the midst of, and not on top of, other beings.

The development of the FAAB was supported by Nordic Culture Fund’s Opstart grant. 

Halldór is an amazing inventor and designer, whose website you should visit: