Under the Hood: Vita Synths 4X-AT-85 MKII
If you’re looking to add some crunchy, characterful grit to your Eurorack setup, the Vita Synths 4X-AT-85 MKII is a module that should be on your radar. This lo-fi drum module is all about delivering that classic 8-bit sound, pulling its inspiration from an 8-bit architecture to create a unique and nostalgic sonic palette.
Based in Prague, Czechia, Vita Synths has packed a ton of functionality into this 20HP module, making it a powerful rhythm hub for any rack.
Overview
The 4X-AT-85 MKII is a 4-channel, 8-bit lo-fi drum module. At its core, it features four microcontrollers that house a total of 32 (4×8) distinct lo-fi drum sounds. It’s designed not just as a sound source, but as a performance tool, thanks to its built-in mixer and, most notably, dedicated external effect loops for each channel. This allows you to send your kick to a dirty distortion and your snare to a washed-out reverb, all from a single, integrated unit.
Features List
- Sound Engine: 4-channel 8-bit digital drum module
- Sound Bank: 32 (4×8) built-in lo-fi drum sounds
- Mixer: Integrated 4-channel mixer with independent level controls
- FX Loops: Per-channel FX Send and Return, allowing for individual external processing
- Mutes: Per-channel mute switches for live performance and arrangement
- Triggering: Responds to falling-edge trigger/gate signals
- Format: Eurorack
- Width: 20HP
- Power: 65 mA (+12V), 0 mA (-12V)
Summary Table
| Feature | Specification |
| Product | Vita Synths 4X-AT-85 MKII |
| Type | 8-bit Lo-Fi Drum Module |
| Channels | 4 |
| Total Sounds | 32 |
| Width | 20HP |
| Depth | 30mm |
| Power | +12V: 65mA |
| Key Features | Built-in Mixer, Per-Channel FX Send/Return, Mute Switches |
Comparison: 4X-AT-85 (Original) vs. 4X-AT-85 MKII


| Feature | 4X-AT-85 (Original) | 4X-AT-85 MKII (Improved Version) |
| Sound Library | 32 total sounds (4 channels x 8 sounds) | 16 total sounds (4 channels x 4 new sounds) |
| Sound Quality | Standard 8-bit sounds. | “Much better” sounding samples, optimized data. |
| Audio Output | Standard level. | Loud audio output. |
| Triggering | Triggers on the falling edge of the pulse, which could introduce a slight delay. | Triggers at the start of the pulse, eliminating delay for tighter response. |
| Audio Circuit | Standard operational amplifier. | Upgraded OPA2134PA op-amp for a “warm tone.” |
| Filtering (LPF) | Single Low-Pass Filter stage. | Precisely tuned LPFs plus a second, switchable LPF stage per channel. |
| Controls | Toggle switches for mutes/functions. | Push-button switches for easier control. |
| Circuit Protection | Trigger inputs were not protected. | Trigger inputs are protected against negative voltage, allowing for safe experimentation (e.g., bipolar LFOs). |
| Appearance | (Not specified, likely black or standard panel) | Stylish blue front panel. |
Summary of Differences
While the original 4X-AT-85 offered a larger library of 32 sounds, the 4X-AT-85 MKII is a technical refinement. It focuses on higher-quality (though fewer) sounds, a much louder output, and zero-latency triggering. The upgraded op-amp, switchable filters, and protected inputs make it a more robust and sonically refined module for performance and sound design.
Pricing & Availability
The module appears to be available for purchase directly from the Vita Synths Etsy store and various used marketplaces. It is not a new-release product and has been available for some time.
Pricing is sourced from various online listings and may vary.
| Currency | Price (Approx.) |
| USD | $160 – $192 |
| GBP | £146.33 |
| AUD | A$293.25 |
| EURO | Available, but price not specified. |
Regional Availability
- USA: Available. Ships to the USA (a review noted fast shipping to California).
- UK: Available. The seller’s page lists free delivery to the UK.
- Europe: Available. The shop is based in Prague, Czechia.
- Australia: Available. The module is listed on the Australian Etsy site.
Footnotes
- VITA SYNTHS Shop: https://www.etsy.com/uk/shop/VITASYNTHS
- Product Discussion Link: https://youtube.com/watch?v=bY4-_HFSfoM


