Future Sound Systems FIL4 Timbral Sculptor Eurorack Filter & Wavefolder Module

The Timbral Sculptor from Future Sound Systems together several synthesis elements designed for altering the harmonic content of audio signals at its input. The module is comprised of a multi-mode filter, VCAs, a deadband wavefolder, and a rectifier and Lockhart wavefolder in the resonance path of the filter.

The Timbral Sculptor therefore can be coupled with one or several oscillators, as well as modulation sources, for a full synthesizer voice. The Filter component of the Timbral Sculptor has been designed to range from clean, low-distortion filtering to chaotic noise generation, particularly through the use of non-linear elements in its resonance path.

The Timbral Sculptor’s multi-mode filter is a -18dB/octave three-pole design based around the SSI2164 IC. When used without the rectifier or wavefolder in the resonance path, the filter behaves “cleanly” with low distortion. The filter will self-oscillate at maximum Resonance, and also has slightly accentuated Resonance at higher Cut-Off Frequency, imitating filters such as that found in the Roland TB-303. 1V/Oct control over the Cut-Off Frequency is available at the Frequency CV1 input, and the Resonance can also be voltage controlled via an attenuverter. Additional features to this filter include the Audio FM attenuverter and, in the resonance path of the filter, a rectifier network and Lockhart wavefolder. These can be employed to drastically change the behaviour of the filter. Each individual state output from the filter is fed through a VCA, courtesy of another SSI2164, and akin to the Cyclical Engine VCO module. The mixed output of this is then passed on to the next component in the Chain, whether that be the Chain Output or the deadband wavefolder named “Timbre”.

The “Timbre” section is named after a well-regarded deadband wavefolder design, prominent in “West-Coast” designs both new and old. Whilst the Filter section of the Timbral Sculptor belongs to classic subtractive synthesis, the Timbre section can be seen as relating to additive synthesis, as the harder the Timbre section is driven, the greater the number of harmonics that are added to the input. The Timbre section can be manipulated using the Drive control (when in Pre configuration) or from the VCAs at the filter’s outputs (when in Post configuration).

The Timbral Sculptor also features an exponential-law VCA, which can be used completely independently from the other elements of the module if desired. Otherwise, the VCA can be placed at the beginning or end of the signal chain. Note that this VCA can be employed when the Timbre section is in the Pre configuration to give voltage control over the Drive.