The Feedback Resonator is a direct upgrade to the Sonic Resonator in Subnautica 2, and it is the only tool that can destroy Armored Cankers from a distance. That matters because Armored Cankers close up the moment you get close to them, making the base Sonic Resonator useless against them. Without the Feedback Resonator, clearing the Angel Comb infestation is impossible, which blocks a significant chunk of progression. The game's own description calls it a "modified sound amplifier" that uses a bacterial feedback system to shatter hardened biomolecules. In practical terms, it is a mandatory upgrade if you want to move forward.
Where to find both Feedback Resonator scan locations
Both scan locations sit inside the Root Canyon Biome, which is a significant swim from the starting Lifepod. The first location is roughly 2052 meters northeast of the Lifepod, and the second is around 2013 meters east. Using the Angel Comb as your reference point is far more practical than navigating from the Lifepod.
Open the Signals menu and locate the Alien Ruins before heading out. Both Feedback Resonators are reachable from that landmark, which saves a lot of aimless swimming.
Feedback Resonator location 1: the yellow pool area
From the Angel Comb, swim northeast and follow the purple roots running along the sand floor. You are looking for a green glow in the distance. Keep moving toward it until you reach a yellow pool. The first Feedback Resonator sits near the edge of that pool.
Here is the part most players get wrong: do not bring your Tadpole into this area. A giant squid patrols the zone and will attack the vehicle as soon as it enters. Park the Tadpole at the entrance, swim in on foot, scan the Feedback Resonator, and leave. You can also grab Troilite deposits while you are there, since they appear in the same area.
Sonic vs Feedback Resonator
Feedback Resonator location 2: the Cicada Wreck Therapy Room
For the second scan, go back to the Alien Ruins and then head between east and southeast. Past the Angel Comb, you will spot ruins in the distance. On top of those ruins sits the Cicada Wreck, identifiable by its open front door. The wreck is about 390 meters northeast of the Angel Comb.
Enter through the south-facing doorway. Once inside, look to the left near a charred door. The second Feedback Resonator is on the floor there. Scan it and you are done with the field work. There is also a damaged door nearby that you can repair with a Repair Tool if you want to explore further.
First scan point, yellow pool
How to craft the Feedback Resonator at the Modification Station
With both scans done, head back to your base and open the Modification Station. The Feedback Resonator appears under the Prototype Tool Modification menu. The recipe requires your existing Sonic Resonator plus four additional materials.
The two Conduit Crystals are the most likely bottleneck here. They are rare and require a dedicated run to find them. Our guide on where to find Conduit Crystals covers the exact location and the quickest route to farm enough for this craft.
The Feedback Resonator replaces your Sonic Resonator. Make sure you have finished any tasks that only require the base Sonic Resonator before committing materials to the upgrade.
How to use the Feedback Resonator to clear the Angel Comb
Once crafted, the Feedback Resonator lets you destroy Armored Cankers from a safe distance, which is the mechanic that makes clearing the Angel Comb infestation possible. The base Sonic Resonator cannot do this because the Cankers seal shut when you approach. The Feedback Resonator fires from far enough away that they stay open and vulnerable.
Clearing all three Angel Comb infestations with this tool earns a permanent environmental tolerance reward. The full step-by-step process for the Angel Comb puzzle is covered in our guide on how to cure the Angel Comb, and if you need to deal with Bloom Infestations elsewhere, the Bloom Infestation clearing guide walks through the Sonic Resonator's role in those encounters too.
What else should you prepare before this run?
The Root Canyon sits far enough from the Lifepod that going underprepared will cost you time. A few things worth sorting out first:
- Tadpole depth upgrades are worth having before this trip. The areas around Root Canyon can push past standard crush depth limits.
- Troilite can be farmed at the first scan location while you are already there, so bring extra inventory space.
- The Scanner is a prerequisite for any scan-based blueprint unlock.
For everything else you need across the full game, the complete Subnautica 2 guides collection has resource farming routes, base building tips, and progression walkthroughs in one place.