The Feedback Resonator is the ranged upgrade for the Sonic Resonator in Subnautica 2, crafted at the Modification Station once you have scanned two fragments hidden near the Alien Ruins. It fires a sonic projectile with an effective range of about 25 meters, which is the only reliable way to break armored Bloom Cankers that seal shut whenever you get close.
Quick answer: Scan both Feedback Resonator fragments (one inside the Cicada Wreck Therapy Room, one near the Metal Farms green pool), then craft the upgrade at a Modification Station using 1 Sonic Resonator, 2 Enameled Glass, 2 Conduit Crystal, and 2 Strontium.
Prerequisites before the run
You need the base Sonic Resonator already built and a Modification Station placed in your base. The Modification Station blueprint comes from the Alien Ruins Research Base, and the station itself costs 2 Titanium, 2 Celestine, and 2 Copper.
A Tadpole vehicle with at least the first depth module is strongly recommended. The fragment area sits well east of the starting Lifepod and includes a Leviathan patrolling near the surface, so you will want maneuverability and a way to retreat.
Feedback Resonator fragment locations
Both fragments sit in the area around the Alien Ruins and the corrupted Angel Comb flower. Use the Alien Ruins marker as your reference point rather than the Lifepod — the swim is much shorter that way.
Fragment 1 - Cicada Wreck (Therapy Room). Follow the Singh blackbox signal east-southeast from the Alien Ruins marker, roughly 770 meters out. The wreck sits on top of ruined alien structures with a clear, open doorway facing south. Enter through that doorway, look to the left near a scorched door, and the fragment is on the floor.
Fragment 2 - Metal Farms green pool. From the Angel Comb, head northeast and follow the purple roots running across the seabed. A bright green glow marks the pool zone. The fragment lies on the ground near the pool's edge, close to a table with stacked barrels. Stay around 400 meters deep to avoid waking the leviathan above.
A third fragment exists in a crevice with Cabbage Shootroot along the path between the power plant and the Metal Farms, in case you miss one of the others.
Crafting recipe
Once both fragments are scanned, the blueprint unlocks at the Modification Station under the Prototype Tool Modification category. The recipe consumes your existing Sonic Resonator, so finish any base-game resonator tasks first.
| Material | Quantity | How to obtain |
|---|---|---|
| Sonic Resonator | 1 | Your existing tool — it gets consumed in the upgrade |
| Enameled Glass | 2 | Fabricator recipe: 1 Glass + 1 Creature Enamel (gooey wall growths on cliffsides) per unit |
| Conduit Crystal | 2 | Solidified seaweed-like growths near the Angel Comb tendrils and around the alien structures |
| Strontium | 2 | Processed from Celestine at the Configure Processor; Celestine is the light grey mineral common in the Alien Ruins biome |
Conduit Crystals are the most common bottleneck. They cluster around the corrupted Angel Comb's roots, so plan a single trip that covers both the crystals and your Celestine farming for Strontium.
What the upgrade actually changes
The base Sonic Resonator only works through direct contact, which is useless against Bloom Cankers — the armored flowers contract the moment you get near them. The Feedback Resonator fires a projectile in your aimed direction, traveling up to 25 meters before detonating in a small controlled explosion. That range is what keeps the Cankers open long enough to destroy them.
Clearing the Angel Comb infestation with the upgraded tool unlocks the fourth Adaptation ability, which lets your character understand the alien language used at the power plant's door and turbine controls. The Feedback Resonator still mines mineral nodes the same way the base tool did, so you do not lose any of the original utility.
How to verify it worked
After crafting, check your hotbar — the Sonic Resonator entry will be replaced by the Feedback Resonator with a new icon. Equip it, aim at a distant Bloom Canker, and fire. A glowing projectile should travel outward and shatter the canker's armored shell on impact. If the projectile fizzles before reaching the target, you are outside the 25-meter effective range and need to swim closer.
If the recipe does not appear at the Modification Station, you are missing one of the two fragment scans. Re-check the Cicada Wreck Therapy Room and the Metal Farms pool before assuming a bug.
Subnautica 2 remains in early access, so biome layouts, signal names, and recipe costs can shift between patches. The fragment locations and recipe above reflect the current build of the game.