Barcelona-based Euro maker Jasmine & Olive Trees let us know about their new drum module that has a unique capability to change function through the use of panel overlays.

Doppler is a compact Eurorack percussion processor that accepts an oscillator, sample, or other audio signal and the module reshapes it into kicks, snares, hi-hats and “stranger stuff in between”.

The engine is a delay-line pitch processor, so a trigger resets the read head, it sweeps down to a target depth, and out comes that falling-pitch kick. A single knob (Mod) sweeps the whole thing continuously, from pitch-shifted chords, through the Doppler kick zone, into FM and cross-modulation for metallic, industrial hits.

Every CV input takes audio-rate modulation, so you can push it somewhere genuinely chaotic if you want to.

That One Weird Trick

Doppler changes its firmware when you lay a different overlay on top of it. No computer, no reflashing, nothing to unscrew. You set an overlay panel over the module, and instantly it’s a different instrument, with the new panel’s labels lined up with the new functions.

This is the first time we’ve seen this feature in a synth module.

The module ships with three overlays included, free.

• Door is a stereo LPG that reacts to pitch and rhythm.
• Doppler is the “drummerizer”.
• Rubin turns it into a stereo ADSR VCA/VCF.
• Lichen makes it a dual AD/VCA.

So the single module can function as a LPG, a drum voice, a stereo ADSR, or a pair of envelope VCAs, depending on which overlay is sitting on it.

The developer says that, because it’s built on a DSP platform, future “family firmwares”can be loaded to the module, as they are developed.

Features:

• Doppler processes external oscillators, samples, or other audio signals into percussive sounds
• The processing range moves from a clean signal through pitch-envelope processing into FM modulation
• Thirteen chord voicings are available
  • Chord voicings include major, minor, suspended, sixth, seventh, ninth, and eleventh chords
  • Chord processing uses four pitch-shifted taps
• The Body input handles the main signal
• The Trans input provides a dedicated transient channel with an auto-tuned band-pass
• VCA and LPG modes are selectable by long-press
• VCA and LPG mode selection is saved to memory
• An independent noise output provides a dust oscillator
• The dust oscillator density tracks the character of the input signal
• CV inputs are provided for Attack, Decay, Mod, and Amount
• Smart Attack provides noise decay when turned to the left and a long swell when turned to the right
• Doppler includes Door, Rubin, and Lichen overlays

Here’s a video demo, via Cinematic Laboratory:

Pricing & Availability:

Doppler is available now for $265 USD.