ESI XSynth: all-in-one digital Synthesizer with poly aftertouch, MIDI controller, and audio interface: available now

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Superbooth 2025: ESI XSynth is an all-in-one Synthesizer with a complete synth engine, polyphonic aftertouch MIDI keyboard, and built-in audio interface.

Good news: The new ESI XSynth is available now at Musicstore.de for 369€ and on pre-order at Thomann. YouTuber JayB, who created sounds for it, has published a new sound demo video. 

Update

Update from May 13, 2025

Last year, the German company ESI unveiled the XSynth at Superbooth 2025. It’s a Synthesizer built into a modified ESI Xkey MIDI keyboard.

At Superbooth 2025, they announced the official release and said the first units are expected to arrive at retailers in the next 1-2 weeks. The price is also confirmed: $379/369€. 

ESI Xsynth Synthesizer

Superbooth 2025: ESI XSynth

The XSynth is a sample-based/looped single-cycle waveform-based 3-oscillator Synthesizer with PWM, sync, and FM capabilities.

Then, it has a custom-designed multimode filter, three AHDSR envelopes, three LFOs, and effects. There will also be an editor for a better engine overview and preset import/export functionality.

The highlight of this new Synthesizer is its extras. In addition to being a solid classic subtractive Synthesizer, the ESI XSynth is also a MIDI keyboard and controller with velocity and polyphonic aftertouch keys based on the ex-CME now ESI Xkey.

The MIDI knobs also handle MIDI CC so you can map it to other hardware and software. According to Lukas, the developer, the MIDI CC numbers are selected so as not to collide with those of the sound engine.

Additionally, the XSynth works as an audio interface. Firstly, you can send the synth’s audio to your computer or tablet via USB. Secondly, it has an AUX input for routing external audio. In a later firmware release, it will also be possible to process it with the synth’s internal filter.

An exciting all-in-one Synthesizer package. I hope I get the chance to review the XSynth for you. In the meantime, here’s my video of the Superbooth 25, including sounds.

 

Update

Update from January 26, 2025

At Superbooth 24, ESI showed a prototype of their first-ever Synthesizer XSynth, a digital synth embedded in an Xkey polyphonic aftertouch keyboard.

There are new details about the Xsynth at NAMM 2025. According to ESI, they use the same keyboard technology as the Xkey keyboard but with shortened keys in length but not width. 

The new ESI Synth will feature a newly developed digital engine with up to 10 voices but never below 8. It hosts three multi-wave oscillators, three LFOs, a modulation matrix, an arpeggiator, a glide, and more.

As the Superbooth 24 news mentioned, the oscillators will feature a wide range of timbres, from classic waveforms to field recordings like sea waves. Xsynth will ship with 128 factory patches and 512 patch memory slots. Plus, an engine editor. 

As an additional bonus, the four knobs on the article also work as a regular MIDI controller with MIDI CC. Plus, it has a built-in audio interface. ESI will also ship the synth with a Synthesizer editor software. 

ESI Synth will be available in April/May for $379/349€.

Update

Article From May 20, 2024

The Superbooth 24 is officially finished. The follow-up reporting is in full swing. Overlooked in the flood of new products was that the German company ESI, known for audio and MIDI interfaces, also makes synthesizers.

At Superbooth 24, ESI showcased the prototype of the Xsynth Synthesizer. 

ESI Xsynth

ESI Xsynth

In the last minutes of SB 2024,I could talk to Lukas, the developer of the Xsynth. According to him, the Xsynth will have three oscillators based on sample-based content stored in the ROM. There will be classic waveforms but extraordinary oscillator samples from field recordings, such as nature.

Then, you will have a filter, three multi-wave LFOs, and three envelopes. In case you say from where you know Lukas. He was once part of the Waldorf development team. So, no unknown developer face. Also familiar are the case and keys of the Xsynth.

ESI uses the same super slim chassis and keybed of the Xkeys keyboards, which have polyphonic aftertouch. This is possible because ESI took over the Xkeys keyboard range from the Chinese company CME.

ESI Xsynth

The synth will have six encoders and many buttons to navigate the menu and operate functions. 

You can find a USB-C port for MIDI, TRS mini jacks for MIDI in and out, a phone socket, a Line out, and auxiliary input on the backside. According to Lukas of ESI, the Xsynth will be both an audio and MIDI interface. 

First Impression

There is no sound demo yet, as the synth is fully developed. But I find the form factor and idea intriguing. Let’s see how it will sound.

All details are not yet public. ESI plans to release the Xsynth in October/November 2024 (estimated).

More information will follow here: ESI 

Superbooth 24 News

Hardware Synthesizer News

20 Comments

    • Which is, inexplicably, the new norm. I think they’re even getting smaller. I’ve held off on the Sonicware stuff because it’s like reading an algebra book through a keyhole with their screens. Yeah, there has to be a paradigm shift. This isn’t the music business, 16 year olds are not the target audience for synths. Or…are they?!

      • Screen size is driven by what manufacturers are making in China. You can get a tiny OLED graphic display for a couple of bucks, and that’s what’s going into a lot of new designs. We had to pay a premium to move up to a 3.6″ display on our units, but the difference is night and day — my aging eyes appreciate being able to read patch information from across the room.

  1. I am so excited for this. No idea why. I have an old wired CME Xkey 25 and if I hook it up to my iphone I have all the synths I want. But all in this package is so tempting if it even sounds good at all.

  2. I have the original CME Xkey 25. At normal listening volume, the key clicks are louder than the VSTi’s sound from the speakers. The keyboard is so loud, that it effectively masks the instrument sound (unless you play in headphones). Nice on papaer, barely usable in practice.

  3. Why can’t they make this exact same instrument, with piano keys and poly aftertouch? Why is that a big deal? Just do it!:)

    • the ESI Xkey keyboard without audio interface, MIDI interface, MIDI controller elements and synth is 149€ 😉

      • looking at the block diagram in the user manual shows its quite a versatile MIDI & audio interface router.

        I think it comes down to it’s main strengths are as a synth engine and the above features.

      • is not a midi interface or synth (to be honest I don’t want the Synth part anyway) and its 155 euro still pretty expensive.

        • I really don’t think anyone with music as a passionate hobby or as a profession, really thinks 155 bucks is expensive. Ask yourself, if you are in one of these categories or if with everything you first see the price and the value to you second. If so, there are millions of software solutions for sounds, 2nd hand markets, deals and cheap alternatives, which make it unnecessary to vent your anger anonymously on the Internet.

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