Benchmark: Mayer EMI MD900 XVA Desktop Synthesizer


Benchmark: Mayer MD900 XVA Desktop Synthesizer

Source: Gear News

At last year’s Superbooth, Austrian developer Mayer EMI unveiled the MD900: an incredibly versatile desktop synthesizer based on the M800-R2 Eurorack module. Meanwhile, the MD900 has hit stores – and our test studio. Here is our first impression of this superb synth from an independent developer.

To note: This article by Marcus Schmahl first appeared in German on

Mayer EMI MD900 XVA Desktop Synthesizer

Horst Mayer, the man behind Mayer EMI, is a visionary developer whose engaging and positive attitude isn’t just evident in conversations with him. It’s also evident in his instruments, especially the MD900 XVA. Every inch of this synth tells a story of hard work, determination and years of experience. Just think of the courage it takes to undertake such a project as a small, independent business in times of component shortages, skyrocketing prices and supply chain issues. For those of you who speak German, here is my interview with Mr. Mayer:

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We took this extraordinary synthesizer through its paces for our review. During all this time we have been in contact with the developer, who had an answer or a solution to all questions and problems. Through the company’s dedicated Discord channel, all MD900 users can enjoy the same level of support I received. Impressive!

Unboxing the Mayer MD900

The Mayer MD900 has a solid fact aluminum frame with beautiful walnut sides. It weighs about 4.4 kg (or just under 10 pounds for Americans) and sits firmly on my studio desk. Similar to the UDO Super 6 Desktop, the MD900 case has two small extendable feet to position it at a slight angle. The synthesizer measures 460 x 295 x 65 millimeters.


Mayer MD900 user interface

The impressive user interface consists of no less than 37 rotary knobs, ten clickable encoders, 23 buttons, 11 small buttons, 42 LEDs and twelve faders. In addition to the main touchscreenthere is five smaller screens that keep you up to date with what’s going on in the different sections.

On the back, the Mayer MD900 has three USB-A ports for connecting controllers or the included USB flash drive, MIDI In/Out/Thru, sustain and expression pedal jacks, a stereo line input, two line outputs (L/R) and a headphone output. This is also where you will find the connector for the external power supply and the power switch.

After turning on the synthesizer, it takes about 20-25 seconds to start. Indeed, it must load the Linux-based operating system, including all wavetables, samples, presets and sub-presets. You can follow the process on the different screens.


Rear connections

Mayer MD900 XVA sound engine

The 4-part multitimbral XVA Sound Engine with 16-voice polyphony is built around a Linux operating system with real-time extensions. Two oscillators and a noise generator are mixed and then sent to a pair of filters. There is one envelope for the filter, two for the amps and an additional one as an additional modulation source for shaping the sound. On top of that, the MD900 offers three LFOs with different waveforms and random generators for lots of movement. The Shaper section was not yet activated at the time of our review, but it is coming soon.

The versatile oscillators are clearly the main event. In wavetable mode, they remind me a bit of the Serum software synthesizer. Each wavetable consists of 256 waves; if there are fewer than that in a given wavetable, the synth automatically generates additional waveform variants to expand the table to 256 waves. Additionally, each oscillator can operate up to four instanceswhich is ideal for wide stereo broadcasts or fat, detuned sounds.


The MD900 offers wavetable and VA synthesis

Hold the Mode button to switch to algorithm mode, in which the oscillators output standard waveforms like saw, sine, pulse and their variations. Additional algorithms include PWM, hard sync, and various formant and phase distortion modes. This mode covers all the bases and lends itself to classic analog-style sounds. For the filtersyou have the choice between different emulations (Moog Ladder, SEM, standard) and high pass, band pass and low pass characteristics.


This solid base is complemented by a massive party effects. Each part offers ten slots for effects such as Mod-Delay (Flanger, Chorus, Vibrato), Param-EQ, Stereo Delay (Normal, Ping Pong), Moog Filter, Tube Amp, Reverb (Room, Hall, Large), Dynamics (compressor sidechain) and Phaser (6, 12 or 18 stages).

This powerful sound engine is obviously capable of an extremely wide range of sounds. Drones, pads, leads, organs, basses, FX, Reese basses, strings – there’s practically nothing the MD900 can’t do. It’s also fairly easy to use if you’re familiar with basic synthesis techniques. For a preview of what the Mayer looks like, watch the Limbic Bits video at the bottom of this page.


The MD900 is as beautiful as it is powerful

An all-in-one music machine

In addition to the sound engine, the Mayer MD900 includes a sequencer and clip launcher it almost feels like a scaled down version of Ableton Live. You can create MIDI clips in seven columns (4 parts synth, drums, CV1, CV2). An additional Master channel lets you launch entire rows of clips simultaneously. Besides recording MIDI using a connected keyboard, it is also possible to import MIDI files via USB.

The first four columns correspond to the four synth parts, which can contain four different sounds. These parts share 16 voices. Clips can also include arpeggios or sequences, which play in sync with the tempo. The clips in the sixth and seventh columns are used to control external devices via MIDI.

So what is the drum column for, you ask? To complete it all, the developer has integrated a drum sample player with 14 channels (Kick, Snare1, Snare2, Closed Hihat, Open Hihat, Ride, Crash, 3x Tom, 3x Percussion, plus one free slot). You can also load your own samples and program grooves using a drum grid editor on the touchscreen.


Lots of buttons


Thanks to its simple and logical panel layout, the Mayer MD900 is quite easy to use right out of the box. Everything is clearly labeled, so it’s easy to find your way around. The controls are precise and pleasant to the touch, and the bright touchscreen is vivid. Just power it up, turn a few knobs, create sounds and make music – just the way it should be! On stage, the LEDs are very useful and the displays are easy to read, even at an angle.

If you want to delve deeper into the sound design capabilities of the MD900, you should definitely download the current manual from the developer’s website. It includes valuable information about things like shortcuts (like holding down a button while turning another button at the same time) and the furthest areas of the menu system.


The synth can be positioned slightly tilted

Towards a bright future

I spoke to Horst Mayer via Twitch and was able to get some interesting news. He’s constantly listening to user feedback and working on refining the synth, and thanks to the open platform, the possibilities are vast. In the near future, he plans to release a USB audio interface for the MD900, which will add additional audio outputs. It smells of multi-tracking and immersive audio!

In addition, he is considering adding a CV clock input (and maybe even additional CV inputs and outputs). We will keep you posted on this. Additionally, the synth can be connected to a network (and the Internet) using a USB network adapter, which allows things like remote maintenance. Horst also thinks of audio over LAN – exciting prospects!

The sequencer, modulation system, drum sampler and audio inputs are also being worked on. Besides a sample morph functionit is planned to implement a vocoder. As you can see, the Mayer MD900 is far from finished, and it will continue to improve.

One thing that’s unfortunately missing is a USB port to connect directly to a computer, but you can fix that by using a LAN adapter (which costs around $10). You will also soon be able to access the file system via LAN and import and export data using drag and drop. For now, data transfer can be done using the included USB flash drive. Another thing that will be addressed in an upcoming update is the filter cutoff knob response, which feels a bit sluggish at its current setting.


The Mayer EMI MD900 XVA Desktop Synthesizer is a very versatile synth that looks and sounds fantastic. Despite its digital nature, it can absolutely compete with most analog synths in terms of sound, while offering greater flexibility and expandability thanks to the engine’s open architecture. The only limitation is available CPU power, but I didn’t encounter any issues during my review.

In short – this thing rocks! It’s obvious that the developer has put a lot of thought into the features and workflow that musicians and sound designers really want. If you’re looking for a synth that can produce just about any sound you can imagine, the Mayer MD900 should definitely be on your list.

Price and availability

The Mayer EMI MD900 XVA desktop synthesizer is available at Thomann* for 3450€.

More information about the Mayer MD900



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