The I-ō47 Multimode Resonator/Filter is a modern interpretation of a vintage circuit design inspired by the classic 1047 module of the ARP2500. It has been designed with some additional features and unique characteristics built in.

The internal VCAs are a new hybrid design combining matched transistors and precision operational amplifiers.

With CV-controllable center frequency, resonance/Q, and notch offset alongside FM, strike, and a complex dual input with wave-shaping limiter, the I-ō47 is truly a filter for all occasions.

I-ō47 | ʌɪ-əʊ-ˈfɔːti-ˈsɛv(ə)n | noun (signal processing) the ins and outs of a classic multimode filter/resonator.

Size

14HP
Depth: 27mm

Power

+12V: 50mA
–12V: 50mA

Specifications

• Center frequency range 16Hz to 16KHz
• 1V/octave, Coarse and Fine frequency controls
• FM input with attenuverter
• Low pass 18 dB/octave
• High pass 18 dB/octave
• Band pass ~6 – 18 dB/octave depending on Q
• Notch with variable offset –/+ 2 octaves
• Input with gain control
• Inverted input with resonance-dependent gain
• Strike input for pinging the filter
• Feedback switch which adds band pass to the input for enhanced resonance
• Limiter based on tanh wave shaper which affects the primary input (post gain fader)