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Introduction

Congratulations on your purchase of an Expert Sleepers “Persephone”. Please read this user 
manual before operating your new module.
Persephone is a VCA (Voltage Controlled Amplifer) using a discrete JFET as the gain element. 
The JFET can be tastefully (or violently) overdriven for saturation/distortion efects.
Persephone also includes a zero-crossing detector, which can be used to restrict gain changes to 
zeros in the audio waveform, preventing clicks and pops that can occur with very fast 
envelopes, especially on lower pitched sounds. In fact, with the zero-crossing circuit engaged, 
you can use a simple gate as the CV input without clicks.
The module's signal and CV paths are 100% analogue (there is a little discrete logic involved in 
the zero-cross circuitry).

Installation

House the module in a Eurorack case of your choosing. The power connector is 16-pin 

Doepfer 

standard

1

. If using the power cable supplied with the module, the red edge of the cable is closest 

to the bottom edge of the PCB, and carries -12V. ("-12V" is marked on the PCB itself next to this 
end of the connector.) Be sure to connect the other end of the power cable correctly, again so 
-12V corresponds to the red stripe on the cable.

Power requirements

Persephone draws up to 33mA on the 

+

12V rail, and 26mA on the -12V rail.

It does not use the 5V rail.

1 http://www.doepfer.de/a100_man/a100t_e.htm

Summary of Contents for Persephone

Page 1: ...User Manual Revision 1 0 persephone ...

Page 2: ...or copied only in accordance with the terms of such licence The content of this manual is furnished for informational use only is subject to change without notice and should not be construed as a commitment by Expert Sleepers Ltd Expert Sleepers Ltd assumes no responsibility or liability for any errors or inaccuracies that may appear in this document ...

Page 3: ...s Introduction 4 Installation 4 Power requirements 4 Inputs and outputs 5 Controls 5 Signal fow 6 Audio path 6 CV path 6 Use as a regular VCA 7 Zero cross detection 7 Calibration 8 Where to get help 8 Acknowledgments 8 ...

Page 4: ...uit engaged you can use a simple gate as the CV input without clicks The module s signal and CV paths are 100 analogue there is a little discrete logic involved in the zero cross circuitry Installation House the module in a Eurorack case of your choosing The power connector is 16 pin Doepfer standard1 If using the power cable supplied with the module the red edge of the cable is closest to the bot...

Page 5: ...CV input CV output Audio input Secondary audio input Audio output The two CV inputs are summed similarly the two audio inputs are summed mixed The Clip LED in the centre of the panel lights when the output exceeds 10V indicating that you ve most likely left the realm of soft saturation and are heading into harsh clipping Controls In addition to the CV attenuator there is a knob for the CV Bias exp...

Page 6: ...hat of reducing the level so it doesn t clip at the output The Asymmetry switch disables part of the circuit that linearises the behaviour of the VCA resulting in positive and negative sections of the input waveform being processed quite diferently increasing the even harmonic distortion The whole audio path is DC coupled CVpath The two CV inputs are summed one via the attenuator and passed to a S...

Page 7: ...of the zero cross feature consider the following in which an envelope with a very fast attack is being applied to a fairly low frequency sine wave The yellow trace is the CV input the magenta is the CV output The green trace shows the module s audio output In this image the zero cross feature is not enabled Notice how the audio waveform rises extremely abruptly as the envelope opens This would be ...

Page 8: ... that will occur at the start and end of each burst On the right with zero cross detection note how each burst begins and ends cleanly at zero Calibration A trim pot marked RV5 on the PCB allows for adjusting the VCA gain Persephone is factory calibrated so that the module gives unity gain with Bias set to 10 Pre set to 0 and Post set to 10 Wheretogethelp Email forum and social media links can be ...

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