The Feedback Resonator is the ranged upgrade to the Sonic Resonator in Subnautica 2, built at a Modification Station after scanning two fragments near the Alien Ruins. It fires a sonic projectile with roughly 25 meters of effective range, which is the only reliable way to break armored bloom cankers that seal their petals when you approach.
Prerequisites before you start
You need a working Sonic Resonator and the ability to reach the Alien Ruins region. A Tadpole vehicle is effectively required for the trip, and the dive into the Metal Farms pool runs deeper than the base hull rating, so plan on a depth upgrade for the Tadpole before you go.
A Modification Station in your base is also mandatory. The Feedback Resonator only appears under the Prototype Tool Modification menu at that station, not at a standard Fabricator.
| Requirement | Why it matters |
|---|---|
| Sonic Resonator (crafted) | Consumed as the base item in the upgrade recipe. |
| Tadpole with depth upgrade | Required to reach the Metal Farms and survive the descent. |
| Modification Station | Only crafting station that unlocks the Feedback Resonator. |
| Processor | Needed to refine Celestine into Strontium. |
Feedback Resonator fragment locations
Two scans unlock the recipe. Both sit on the east side of the Alien Ruins marker, past the Angel Comb. A third fragment also exists in a Cabbage Shootroot crevice along the route between the Karakorum Power Plant and the Metal Farms, which is useful as a backup if you miss one of the others.
Fragment 1 — Cicada Wreck (Therapy Room). From the Alien Ruins, follow the Singh blackbox signal roughly east-southeast for about 770 meters. The wreck sits above the Upper Generator Control Room at the Karakorum Power Plant, and the fragment is on the floor inside the room with the open front door.
Fragment 2 — Karakorum Metal Farms. Head northeast from the Angel Comb until you reach an area with a bright green pool. Park the Tadpole at the edge, since a leviathan-class creature patrols inside the zone and will attack the vehicle. Swim in on foot and grab the fragment from the ground near the pool.
Crafting materials
The recipe calls for one Sonic Resonator plus three resource types that all come from the Alien Ruins biome. Gather these on the same trip you use to scan the fragments to avoid repeat dives.
| Material | Quantity | Source |
|---|---|---|
| Sonic Resonator | 1 | Existing crafted tool |
| Enameled Glass | 2 | Fabricator recipe combining Glass and Creature Enamel; enamel is harvested from the needle-like pump creatures jutting from cliff sides |
| Conduit Crystal | 2 | Crystalline growths resembling solidified seaweed, found near the tendrils of the corrupted Angel Comb and in the crystal cave between the ruins areas |
| Strontium | 2 | Refined from Celestine in a Processor (30-second processing time per batch); Celestine deposits are common in the Alien Ruins biome |
Creature Enamel requires the Sonic Resonator to break the pumps loose, so make sure your base tool is on the hot bar before the trip.
Crafting the upgrade
Step 1: Return to your base and load Celestine into the Processor. Select the Strontium recipe and run it until you have at least two units; each batch takes about 30 seconds.
Step 2: Combine Glass with Creature Enamel at the Fabricator to produce two Enameled Glass. Confirm Conduit Crystals are in your inventory at the same time.
Step 3: Open the Modification Station and select Feedback Resonator under Prototype Tool Modification. With the Sonic Resonator, 2 Enameled Glass, 2 Conduit Crystal, and 2 Strontium present, the panel will display "Ready to craft." Confirm to consume the Sonic Resonator and produce the upgraded tool.
How the Feedback Resonator behaves
The upgraded tool fires a sonic projectile in the direction you aim. The blast carries roughly the same force as the close-range Sonic Resonator pulse but travels up to 25 meters before dissipating in a small controlled detonation. That range is what lets you destroy armored bloom cankers, which curl their petals shut and become invulnerable when anything gets close.
You can still use it like the original tool at point-blank range against ore nodes and biofilm, so there is no reason to keep the base Sonic Resonator in rotation after the upgrade.
What it unlocks
Clearing armored bloom cankers feeds directly into the fourth Angel Comb Adaptation, which grants the ability to understand the extraterrestrial language used at the alien door and turbine. Without the ranged blast, that progression line stalls at the cankers, blocking the relevant sites.
You will know the upgrade worked when a fired shot visibly travels outward and detonates at range, and when a sealed bloom canker shatters from a distance instead of contracting away from you.