A multi-mode filter inspired by the Steiner-Parker Synthacon.
According to Tiptop Audio, the Forbidden Planet’s filter design is influenced by that found on the Steiner-Parker Synthacon, a three-VCO analog mono synth that was released in 1975.
Like the Synthacon filter, the Forbidden Planet has high pass, band pass and low pass modes with input jacks for each. The resonance uses an internal feedback path which can sound “smooth or aggressive” depending on the setting.
As Tiptop Audio’s video demonstrates, the Forbidden Planet is capable of making some wild sci-fi sounds thanks to the frequency setting and attenuator’s dedicated CV inputs.
The filter’s resonance doesn’t have CV control but does seem to be able to make very unusual effects depending on where you turn the dial. “At a low setting, it emphasizes the cutoff harmonics, at middle settings it begins to self oscillate, and towards maximum setting it forms interesting tones and all sorts of chopped grainy bits of self-oscillation,” Tiptop says.
Tiptop Audio’s Forbidden Planet is available now. It’s 8HP wide and costs $120 – find more information at the Tiptop Audio website.