4Q File

What are 4Q files and how to open them

Are you having problems opening a 4Q 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 4Q files.

What is a 4Q file?

A .4Q file is a Quartet ST Module file.

The Quartet ST Module (.4Q) is a digital music module file used by the Atari ST version of the "Quartet" sample-player and composer program published by Microdeal in the late 1980s. It bundles together musical patterns and instrument (voice) samples so a complete 4-voice track can be replayed by the program without needing separate sample files.

Quartet operates similarly to a tracker: users load or sample a set of instrument voices, then compose patterns for up to four simultaneous voices (channels). The .4Q file stores both the pattern data (notes, order, structure) and the sample (voice) data together, so playback tools or utilities like "Quartet Player" or "Separate" can extract, convert, or play back the module, including versions that support stereo on the Atari STe.

Internally the file starts with the ASCII signature "QUARTET" at offset zero.

How to open 4Q files

Important: Different programs may use files with the 4Q file extension for different purposes, so unless you are sure which format your 4Q 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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