EIBOS Tetras Adds Four Independent Drying Chambers to the Bambu Lab AMS

A new upgrade from EIBOS turns the Bambu Lab AMS into a four-chamber filament drying and storage system, with each spool controlled independently. The Series X Tetras replaces the AMS lid and adds dedicated heaters, screens, and automatic vents, letting you dry PLA, PETG, ABS, TPU, and moisture-sensitive nylons side by side without swapping spools or guessing at settings.

How the independent chambers work

Each of the four bays has its own 60W heater, small control screen, and temperature preset. You can set one chamber to 55C for PETG, another to 60C for ABS, and keep a fourth in storage mode at a lower humidity setpoint. The dividers between chambers are acrylic, not just plastic walls, and they do a decent job of keeping heat bleed under control. In testing, adjacent chambers stayed within a few grams of each other during two-hour drying runs.

The back of each chamber has an auto-opening vent. Most filament dryers make you manually remove a cap or open a hole to let moist air escape. The Tetras vents open only when the chamber is actively heating, then seal shut once the cycle ends. That matters for long-term storage because it keeps ambient humidity out once the spool is dry.

Drying while printing

Bambu Lab's own AMS2 Pro includes drying, but it only runs when the printer is idle. The Tetras can stay active during a print if you switch it to second-stage drying mode. That mode drops the target temperature by 10C to 15C so the filament stays flexible enough to feed without jamming the gears. For anyone running long multi-color jobs, that is the difference between a failed mid-print swap and a clean layer change.

Temperature limits and real-world results

The Tetras locks its maximum temperature to 65C when mounted on the AMS. EIBOS says the heater itself can reach 100C, but the firmware caps it to protect the AMS housing and internal components. That ceiling is fine for PLA, PETG, TPU, and ABS, but extremely hygroscopic materials like nylon CF need longer cycles or a separate high-temp dryer. In hands-on tests, a 500g spool of wet Bambu High-Flow PETG lost about 4g of water weight over a standard six-hour cycle, and stringing on test prints improved noticeably afterward.

Assembly and fit

Installation takes about 20 minutes and does not require firmware changes or soldering. The kit includes the upper cover module, a power hub, four controller screens, acrylic baffles, feed guides, and heat blockers that sit between the heater and the AMS gears. The whole assembly adds roughly 50mm of height to the AMS stack. Under normal use it draws 240W total when all four chambers are heating, then drops to near idle in storage mode.

Is it worth buying?

The Tetras costs $179 for the four-chamber version. That is not cheap, but it is cheaper than upgrading to an AMS2 Pro and it works with printers you already own. If you only ever print one material at a time, a smaller single-chamber dryer or better sealed storage will save money. If you leave four spools staged for color changes, long jobs, or frequent material swaps, independent control is a real quality-of-life upgrade. The auto-venting and humidity-controlled storage mode are features most cheap dryers skip entirely.

Bottom line

The EIBOS Tetras is the most thoughtful AMS-specific accessory on the market right now. It does not try to replace a standalone filament dryer. It does one job: make the AMS you already have more capable without forcing every spool through the same conditions. For Bambu owners who treat multi-material printing as a daily workflow rather than an occasional experiment, it is an easy recommendation.