I-ō47

Instruō's multimode resonator and filter in 14 HP, a modern take on the ARP 2500's 1047: low pass, band pass, high pass and notch at once, on a steep -18 dB/oct slope, its semi-discrete VCAs built from matched transistor pairs and precision op-amps. Its resonance pings from a strike input and, with feedback on, self-oscillates as a sine that tracks 1V/Oct; a limiter shapes the input, an inverting input blends against the resonance.

Key features

• Simultaneous low pass, band pass, high pass and notch outputs
• Self-oscillating resonance with a feedback toggle, 1V/Oct tracking
• Strike input to ping the resonance
• Notch offset, ¼ to 4 times the centre frequency, with CV
• Gain fader into a tanh[3] limiter/waveshaper
• Inverting input, its level falling as Q rises