Creative Cross Modulating Eurorack Filters // Double Bubble by Thonk Synth

video upload by DivKid

"Here we have a new Eurorack DIY stereo filter from Thonk Synth. It's a stereo analogue multi mode filter made for creative modulation. Whether it's dual parallel channels, series filer routings, mono to stereo, stereo in and out or even mono filtering with a separate filter modulator (a filter modulator? What? - heads up, it's ace!). Check out the patches below."



"Double Bubble is a 16HP Eurorack dual analog multi‑mode filter designed for creative sound design and flexible signal processing. Each channel features an analog filter core that can operate in one of four modes – Low‑Pass, High‑Pass, Band‑Pass, or Notch. The input of Channel A is normalled to Channel B so its easy to create stereo filter patches from a mono sound source.

The two channels of Double Bubble can run as independent dual mono filters or be linked together for stereo operation. The filters can also be routed in serial configuration to create more complex signal paths such as a variable width bandpass or notch phasing effects. The SPACING control and wide range of CV inputs give deep modulation possibilities such as dynamic formant style filtering.

The FEEDBACK and XMOD (cross‑modulation) controls add further interaction between the two channels, ranging from subtle harmonic enhancement at low settings to more extreme, self‑modulating textures when increased. The dedicated V/OCT inputs for each channel allow the filters to function as FM oscillators or tone sources when pushed into self‑oscillation. This flexibility allows the Double Bubble to cover a wide range of roles, from precision cascading filter patches to dynamic stereo filtering and experimental feedback adventures!

Features:

Dual analog VCF with LP, HP, BP & Notch outputs
Resonance control per channel with switchable compensation
Mono, serial, parallel, stereo link routing options.
Cross modulation (XMod), FM and V/oct inputs per channel
Feedback with positive & negative phase
Frequency Offset Spacing with CV control
LED indicators for visual feedback on modulation and modes.
Designed in-house at Thonk"