.X7L

What it is

An .X7L is a library file for Yamaha MODX and Montage hardware. It loads into one of the instrument's library slots and appears alongside the factory content.

This one is different from every other format here: the audio is inside the file. There is no folder of WAVs to keep beside it, because the samples are packed into the library itself. One file is the whole instrument.

Kit Name.X7L

What is inside

The container is binary and big-endian, opening with a Yamaha identifier and a version string. Inside, a catalogue of fixed-size elements describes each waveform and points at the audio packed further down the file.

YAMAHA-YSFC        file identifier
4.0.5              format version
...
DWFM element       64 bytes, one per channel
DPFM block         performance data

Vocabulary

Yamaha calls the mapped audio a waveform and the playable result a performance. A waveform with its key mapping is what Ableton would call a multisample and Kontakt would call an instrument.

The X7 prefix covers a small family. An .X7L is a library, and it's the one you want for loading a set of sounds into a MODX or a Montage.

What reads it

Yamaha MODX, MODX+ and Montage, including MODX M. Load it from a USB drive through the Utility Contents Load screen, into a library slot.

Yamaha's own Waveform Editor writes this format, which is the reference any other writer has to match. Sample Miner's writer was reverse-engineered from Waveform Editor 2.5.1 output and checked byte for byte against three of its libraries before being tested on hardware.

The limits

A waveform holds at most 255 channel elements, because the element count is stored in a single byte. A keybank holds at most a left and right pair, so there is no path to more than two channels in one zone.

Because the audio lives inside the library, file size tracks the length of the material rather than the size of the mapping. A large multisampled instrument produces a large .X7L, and the library slot has to hold all of it.