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Expert Sleepers Lorelei

¥25,900 (Tax excluded ¥ 23,545)
Uses discrete transistor OTA. Expert Sleepers analog oscillator

Format: Eurorack
Width: 8HP
Depth: 42mm
Current: 55mA @ + 12V, 54mA @ -12V

Manual Pdf (English)

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Expert Sleepers Lorelei is an analog oscillator with quadrature sine wave output, wave shaping and sync / cross modulation capabilities.This unit, which implements a discrete transistor OTA circuit, is equipped with three waveform outputs.All of these outputs are affected by the same wave shaping control.The first output provides a square wave with a variable pulse width, the first of the remaining two sine wave outputs provides a waveform like a triangle wave, and the second output provides a waveform like a sawtooth wave.These two are orthogonal sine wavesIt is generated based on (90 degrees out of phase).Also, the cross-modulation input is similar to a typical VCO sink input, but it allows you to generate a wide variety of sounds by expanding the nuances of the operation.


Lorelei's I / O jack lights red for positive voltage and blue for negative voltage.The audio signal looks purple because the plus and minus alternate quickly.Inputs with attenuators are dotted with jacks and corresponding attenuator knobs. Lorelei's I / O jacks are arranged from top to bottom as shown below. 

  • Pitch CV input (1V / Oct)
  • Linear FM input
  • Exponential FM input.With attenuator
  • Cross-Modulation / Sync input
  • Wave Shape CV input.With attenuator
  • Square / Pulse output
  • Sine / pseudo-Triangle output
  • Cosine / pseudo-Saw output


In addition to the three attenuators, the Lorelei front panel has an 3-position octave selection switch knob (white), a Tune control (blue), and a Shape control (green). The Tune knob adjusts the oscillator pitch up and down by about an octave. 

Wave Shapes

The Wave Shape CV input and knobs control the waveforms of the three outputs at the same time.Interestingly, if you perform wave shaping correctly, the pitch of the sine and cosine output will be doubled at the midpoint.The image below shows an oscilloscope trace of the three outputs of operating the Shape knob from 3 to 2. 

Cross-Modulation / Sync

A typical sawtooth-based analog VCO performs oscillator sync by resetting the ramp integrator based on the frequency of the sync signal. Lorelei can achieve similar effects, but it behaves differently. In Lorelei, the Sync input basically prevents the oscillator from oscillating when the input is above a certain voltage value (about 3.3V).However, this is not an on-off operation, so the effect is gradually applied as the voltage value increases.As a result, the smooth waveform of the sync input (sine wave, triangle wave, etc.) produces a different effect than the square wave or pulse wave.Also, when a pulse wave is used as the sink input, the pulse width of the signal has a significant effect on the result.In the example below, the Lorelei output is shown in the upper row (green) and the sink input waveform is shown in the lower row (magenta).

Sync with ± 5V sine wave:

Sync with ± 5V triangle wave:

Sync with ± 5V sawtooth wave:

Sawtooth wave with reduced amplitude for Sync trigger:

Sync with pulse waves of various pulse widths of ± 5V: