CF1 File

What are CF1 files and how to open them

Are you having problems opening a CF1 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 CF1 files.

What is a CF1 file?

A .CF1 file is a Common Loudspeaker Format Binary file.

Common Loudspeaker Format Binary (import_format_name Common Loudspeaker Format binary v1, Type 1) is a binary data file used to distribute loudspeaker performance and directivity data. It converts measurements made around a loudspeaker into a fixed-format binary that software tools (like prediction programs or CLF Viewer) read to display spl levels, polar responses, and related loudspeaker characteristic information. Its purpose is to allow loudspeaker manufacturers to produce verified directivity files with standard resolutions so that users of room-acoustics and loudspeaker-prediction tools can rely on consistent data.

The binary version is generated from a text/tab-delimited format authored by the manufacturer, which includes measured impulse responses taken around the loudspeaker under anechoic conditions at set angular increments. For this Type 1 version the angular resolution is 10° and frequency resolution is one octave per band. Once verified in the CLF Viewer, the text file is converted into the binary CF1 distribution file. The binary format ensures data security, traceability of origin, and compatibility with tools that use the Common Loudspeaker Format.

Files created in this format begin with a signature header indicating a version marker ("v1") for Type 1. Specifically the file signature shows a sequence that includes ASCII "v1" early in the file, to indicate Common Loudspeaker Format version 1 Type 1.

Data in the file provide sound pressure level (SPL) values as functions of frequency band and direction around the speaker in both azimuth and elevation, arranged on a spherical grid with 10° spacing between measurement angles. Frequencies are banded in full octaves. Additional metadata identifies the loudspeaker, measurement settings, maximum gain, sensitivity and other core parameters needed by prediction tools.

The file signature for this format is: bytes at offset 0 = 0x40BD0A000100000000000000000000000000000076312E, which corresponds to ASCII elements including the version string v1.

How to open CF1 files

Important: Different programs may use files with the CF1 file extension for different purposes, so unless you are sure which format your CF1 file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single CF1 opener which you will find listed below.

Last updated: August 31, 2026

Various apps that use files with this extension

These apps are known to open certain types of CF1 files. Remember, different programs may use CF1 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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