A2F File

What are A2F files and how to open them

Are you having problems opening an A2F file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your A2F files.

What is an A2F file?

An .A2F file is an Adlib Tracker II Instrument file.

Adlib Tracker II Instrument files with the extension .A2F store instrument definitions for the Adlib Tracker II (AT2) music tracker, including optional "FM-register macro" data. These files define the sound of a single instrument using FM synthesis settings such as operators (carrier and modulator), envelope shapes, connection types, and optional macros that automate repeated register changes for that instrument. An .A2F file is created when you use AT2's Save-Instrument command with FM-register macros enabled.

In workflow, .A2F files are intended to be loaded into Adlib Tracker II just like standard instrument files without macros (.A2I), but with additional macro data conveying per-instrument FM register changes. If an instrument has no macro data, it still can be saved using .A2F. Songs built in AT2 reference .A2F-format instruments and render them on OPL-chip hardware or via AT2's OPL3 emulation during playback.

Byte signature identifies .A2F files: at offset 0 they begin with the ASCII string "_a2ins_w/fm-macro_" (in hexadecimal: 5F 61 32 69 6E 73 5F 77 2F 66 6D 2D 6D 61 63 72 6F 5F). This header distinguishes .A2F files from other AT2 instrument formats.

How to open A2F files

Important: Different programs may use files with the A2F file extension for different purposes, so unless you are sure which format your A2F file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 16, 2026

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