What is a .hlx file?

Every .hlx is a JSON document with four top-level keys: schema, version, meta and data. The preset itself lives under data:

• data.meta — the preset name, the application that wrote it (HX Edit, Helix when the device exported it itself, or Helix Native), and a packed firmware version.
• data.device — a numeric id for the hardware the preset belongs to. This is the field that distinguishes a Helix preset from an HX Stomp or HX Effects one.
• data.tone — the signal chain. dsp0 and dsp1 are the DSP paths, each holding block0…blockN plus its input, output, and split/join markers. Alongside them sit snapshot1…snapshot8 and a controller map that records footswitch, expression pedal and MIDI CC assignments.

A single block, trimmed, looks like this:

"block0": {
  "@model": "HD2_DistScream808",
  "@enabled": true,
  "@position": 0,
  "@path": 0,
  "@stereo": false,
  "Gain": 0.52,
  "Tone": 0.65,
  "Level": 0.67
}

@modelis Line 6’s internal model name — here a Tube Screamer 808 — and the remaining entries are that block’s parameters, stored as normalised 0–1 values rather than the numbers printed on the knobs.

Three extensions turn up when moving presets around, and they are not interchangeable:

Helrig reads all three. Opening a .hxb or .hls lists the setlists and slots inside, and any preset can be pulled out of one and edited as though it had been exported on its own.

The data.device id maps to one of three hardware families, and they differ in ways that matter when a preset moves between them:

Helrig can convert a preset between these families and reports every change it had to make — amp and cab blocks dropped for HX Effects, snapshots beyond the target’s count, footswitch assignments with no matching switch on the destination.

Drop it onto the Helrig editor. The file is parsed in your browser — nothing is uploaded — and you get the whole signal chain: blocks and their parameters, amp and cab pairings, parallel splits, snapshots, and controller assignments. Edits export back out as a standard .hlx that the hardware loads the usual way.

Line 6’s own HX Edit opens .hlx files too, on a desktop with the software installed. Helrig needs neither, which is the point: any modern browser on a desktop, iPad or phone will do, and no account is required.

Line 6 does not publish a .hlx specification. Everything above is read out of real files rather than from a document: the structure described here holds across all 1,246 presets in the corpus Helrig is developed and tested against, every one of which declares schema: “L6Preset” and version: 6.

That is a strong sample, not a guarantee. A firmware release could introduce a field this page has never seen, and Helrig is written to show a block’s raw internal name rather than invent a friendly one when it meets something unfamiliar.

Helrig is an independent, one-person project. It isn’t built by, affiliated with, or endorsed by Line 6 or Yamaha — “Line 6”, “Helix” and “HX” are their trademarks.