Wersi EX 20 MIDI Expander

via this auction
"Imagine having 8 different sounding keyboards all at your fingertips!!! You are bidding on a Wersi EX 20 MIDI Expander. This is a digital synthesizer capable of playing up to 20 polyphonic notes on eack key. Up to four different sounds can be played simultaneously. These sounds are based on a configuration of sound modules. Each voice is entirely independent from other voices and each voice has its own wave, pitch-envelope, amplitude envelope, routing, and volume. The EX 20 also features analog effects to produce fourier, waveform sample, and modular synthesis. The front panel features a set of 16 drawbar sliders for each synthesis mode. You can create your own custom waveform. A 61 note velocity & pressure keyboard can be split and provide up to four different timbres simultaneously per side. The EX 20 is the rack mount version of Wersi's MK1 Keyboard Synthesizer. Both instruments can 'see' up to 16 midi channels for multi-timbral operation, and can transmit on up to 8 channels at one time. The back of the unit features the following connections:

* 1/4" Headphone Jack
* (2) Two programmable footswitches
* Volume control connection
* MIDI in
* MIDI out
* MIDI thru
* Left/Right/Stereo 1/4" output jacks

The EX 20 will expand your synthesizer, organ, or keyboard instrument and it's capabilities into a new dimension of sound and features! With the EX 20 Expander, you have added virtually eight additional keyboards to your present instrument which can be controlled through MIDI from your present instrument, a sequencer, or a computer. This Expander is perfect for not only the keyboard player but also the Hammond, theater organ enthusiast, or the contemporary church organist. Not only does this unit have bank after bank of sounds, you can also create sounds with it using the drawbars. "

Update via Qwave in the comments: "I think the seller does not really know the fact of this unit.

He writes: "This is a digital synthesizer capable of playing up to 20 polyphonic notes on eack key." So 61 keys x 20 notes = 1220 voices? In fact you get 20 voices all together. And up to four parts stacked (then 5 note polyphonic only.

"The EX 20 also features analog effects to produce fourier, waveform sample, and modular synthesis."
There is one ensemble/chorus FX present. Actually it is the same board as the Wersi Voice. And there is one (1) filter for all voices together. So it is paraphonic as the Korg Poly 800 and others.
You create sounds additiv or in an organ register mode (and then use the paraphonic filter for substractive synthesis). Fourier synthesis would create additive spectrums via analysing a given sound. Not possible here. You can create different additive spectrums for 4 keyboard ranges. No sampling.
The synthesis methods available are somehow very often described wrong on internet pages. Maybe people are copying info without owning and knowing the synth.

Without the manual you are totally lost on this synth. And even as experienced synth user, I did not get to work the Midi sysex to work on this synth or the similar Wersi Stage Performer."

Remember, you can do a search for Wersi EX 20 for previous posts with more info including video as well.