Joranalogue - Filter 8

Filter 8 is a fully voltage-controllable OTA multimode circuit, which can also be used as an eight-phase sine oscillator, a VC-LFO or a percussion voice. In addition to high-pass, band-pass and low-pass characteristics with gentle to powerful results, the module offers a vocal-like sounding band-boost / notch combination as well as a phase shifter. In VCO / LFO mode, the module can be played over a range of more than five octaves. Used as a drum voice, Filter 8 produces wooden to metallic sounding percussion.

Filter 8 provides two audio inputs, which are mixed internally. On the output side, there are eight sockets. They offer various filter characteristics and different phase positions, in detail:

• Low-pass filter with an edge steepness of -6 dB per octave / Phase shift by 45 degrees
• Low-pass filter with an edge steepness of -12 dB per octave / Phase shift by 90 degrees
• Low-pass filter with an edge steepness of -18 dB per octave / Phase shift by 135 degrees
• Low-pass filter with an edge steepness of -24 dB per octave / Phase shift by 180 degrees
• High-pass filter with an edge steepness of -6 dB per octave / Phase shift by 225 degrees
• Band-boost plus notch filter / Phase shift by 270 degrees
• Band-pass filter with an edge steepness of -24 dB per octave / Phase shift by 360 degrees

Instead of a cutoff knob, there are Coarse and Fine potentiometers. Linear and an exponential CV inputs with bipolar attenuators are available for modulation purposes. The first mentioned voltage control channel can be AC-coupled via a switch. This allows you to create exceptionally clean filter FM modulations. The resonance can be influenced via a potentiometer and a CV input plus bipolar attenuator as well.

High resonance values make the filter self-oscillate. Thanks to the 1v / octave input and temperature compensation, the module can be played over a range of more than five octaves. A switch can be used to choose either VCO or LFO frequency range. Thanks to the varied phasing of the outputs, eight sine waves, each shifted by 45 degrees, are emitted. Unfortunately, the waveforms’ levels don’t match. But no worries, there is a switchable compensation circuit which handles this problem. A Hold switch and gate input allow you to freeze the oscillating filter core. – A great feature for creating sync sounds. A Ping trigger input makes it very easy to use Filter 8 as a percussion generator. Hint: By connecting one output to the second audio input, interesting feedbacks can be created. – Be sure to try it out!