Filter 8

Description

Representing the cutting edge in modular analogue voltage controlled filter (VCF) design, Filter 8 offers more possibilities and higher fidelity in 12 HP than ever before.

Starting from the classic OTA-style 4-pole cascaded lowpass (LP) topology, Filter 8 features separate LP outputs, each with their own character. Additional filter responses are achieved by pole mixing: 1-pole highpass, a special band boost and notch response, phase shifter and 4-pole bandpass. All outputs are available simultaneously.

Key to Filter 8’s performance is the innovative resonant feedback circuit. By increasing the resonance, all outputs will resonate at the filter frequency, without any low frequency response loss. At higher resonance levels, self-oscillation is achieved, turning the module into an excellent 8-phase sine wave voltage controlled oscillator (VCO) with temperature and switchable gain compensation, low distortion, constant amplitude and accurate frequency tracking over at least 5 octaves. At sub-audio frequencies, Filter 8 can function as an 8-output voltage controlled slew modifier or 8-phase low frequency oscillator (LFO).

Simultaneous exponential and linear frequency modulation is possible, for classic FM tones or chaotic modulation. A hold feature is also provided, ‘freezing’ the output voltages manually or under gate control. This is useful for halting modulations, or as a sync-like effect at audio frequencies. The dedicated ‘ping’ input allows you to easily create crisp percussive sounds with different timbres.

While rooted in the legacy of classic synthesisers, Filter 8 provides a new approach to musical signal generators and modifiers: instead of simply a VCF, VCO, slew modifier or VCLFO, a single analogue module can now be any of those, and anything in between.

Analogue ‘OTA style’ cascaded 4-pole lowpass VCF with self-oscillation capability.
Filter outputs: 1-through-4 pole lowpass, 1-pole highpass, band boost+notch, phase shifter, 4-pole bandpass.
Self oscillation: 8-phase sine waves, separated by 45°.
Accurate temperature-stable sine wave VC(LF)O with fine and coarse tuning.
Simultaneous exponential and linear FM, including depth polarisers, dedicated 1 volt/octave input and LFM AC-coupling switch.
Unique voltage controlled resonance topology: all outputs resonate with absolutely no loss of low frequency response, unlike common ‘bass compensation’ methods.
Resonance compensation gain switch: adjusts output gains for equal amplitude self-oscillation (10 Vpp).
LF mode for slew modifier or LFO use. Ultra-wide total frequency range: 2.8 mHz (6 minutes) to 27 kHz, a range of nearly 10,000,000:1!
Dual signal inputs increase patching flexibility.
Impedance-compensated outputs with dual-colour LEDs.
Voltage hold feature ‘freezes’ the filter core. Pause LFO modulations, or create pulse-width-sensitive sync sounds at audio rates. Also useful as clickless output mute. Manual or gate control.
Dedicated ping trigger input: ‘strike’ the filter core using any trigger or gate signal and easily create percussive sounds with 8 different timbres.
Trim potentiometers accessible from the front panel.
Precision-milled 2 mm anodised aluminium front panel with high-resolution, non-erasable graphics.
Bullet-proof design: polarised power header and MOSFET protection circuit.osc
Includes 16-to-10-pin Eurorack power ribbon cable.
Premium mounting hardware: black screws, black nylon washers and matching hex key.
High-quality components and assembly; designed and made in Belgium.

Dimensions
12 HP
30 mm deep

Current Draw
75 mA +12V
75 mA -12V
0 mA 5V