This document contains details on the floppy disk and file formats used by S-series Akai samplers from the S900 to the S6000, with some notes on MPC and other Akai formats. It has been reformatted and made available on The Sonic Spot with permission from the author, Paul Kellett.

The information contained in this document was worked out by experimenting with the floppy drive parameter table until Akai disks could be read, and then examining the data of numerous disks and files, comparing the contents to the sampler's parameter settings and SysEx data. Paul Kellett is happy to receive corrections or additions to include in this document.

Contents

1. Akai Disk Format Overview
2. S900, S950 Disk Format
3. S900, S950 Sample Format
4. S1000, S1100, S01 Disk Format
5. S1000 Sample Format
6. S1000 Program Format
7. S3000 Disk Format
8. S3000 Sample Format
9. MPC2000 File Format
10. Teledisk Format
11. MESA File Format
12. S5000/S6000 Sample Format
13. S5000/S6000 Sample Format
14. PC Floppy Drive Programming
15. This Document

1. Akai Disk Format Overview

Akai floppy disks are formatted as 2 sides of 80 tracks with 5 or 10 sectors per track. Each sector is 1024 bytes long, giving a total of 800k (low density) or 1600k (high density). PCs use 9 or 18 sectors of 512 bytes and will not read Akai floppies without reprogramming. As far as I can tell, Mac floppy drives can't read Akai floppy disks at all.

Unwritten bytes on a disk are set to zero. Multi-byte values have the lsb first (little-endian). This document refers to the first byte in a block as 'byte 1', not 'byte 0'. All values are decimal unless otherwise stated.

Akai hard disks and CD-ROMs use the same file format as Akai floppy disks, and virtually the same disk format.

2. S900/S950 Disk Format

Track 1, side 1 starts with 64 entries of 24 bytes as follows:

Bytes 1536 to 3136 (1536 to 4736 for high density) contain a map of how the blocks on the disk are used, in the form of 2-byte unsigned integers. For example, if a file starts at block 5, map entry 5 may contain the value 6, indicating that the next block to read is block 6. The next block to read is then given by map entry 6. The map entry for the last block of a file contains the value 32768. Unused blocks have a map entry of zero. The first 4 blocks are needed for the file entries and map.

Note that the S950 can use high-density disks and can read S1000 disks, but the S900 can only read S900 or S950 low-density disks.

3. S900/S950 Sample Format

A S900 sample file has a header of 60 bytes as follows:

(I don't know what is held in the last 20 bytes, but the values shown seem to work).

You can use lower case letters in filenames (not available from the front panel) but avoid unusual ASCII characters. Do not put two files with the same name on a disk!

The header is followed by the (12-bit signed) sample data, packed in a very strange way: For a sample of N words, the upper 4 bits of the first byte contains the lower 4 bits of the first word. The lower 4 bits of the first byte contain the lower 4 bits of word N/2. The second byte contains the upper 8 bits of the first word. This repeats for the first N bytes, after which there are N/2 bytes containing the upper 8 bits of the last N/2 words.

4. S1000 Disk Format (and S1100 and S01)

With the S1000, Akai abandon ASCII (mostly) and use their own alphanumeric code, which shall be referred to as AKAII:

There is a volume label at the end of the map (byte 3136 or 4736 depending on density) consisting of a 12 byte AKAII name followed by 0, 0, 0, ID, 0, 1, 1, 0, 0, 0, 50, 9, 12, 255 where ID = 3 for the S1000.

Note that the S01 uses the S1000 format for disks and samples, but with an ID of 1,0 for high density and 0,1 for low-density unused entries. The S1100 probably uses the same format with a different ID.

5. S1000 Sample Format

The S1000 sample file has a 150 byte header:

The sample data follows the header as signed 16-bit words.

6. S1000 Sample Format

The S1000 program file consists of a 150-byte header followed by one or more 150-byte keygroup entries.
Most parameters are stored as signed or unsigned single bytes.

8. S3000 Sample Format

The S3000 sample has a 192 byte header:

Sometimes the sampler will insert more blank space at the end of the header! Make sure your samples are at least a few thousand words long or they will not play correctly. The sample data follows the header as signed 16-bit words. For details of the S3000 program format see the SysEx information on Akai's web site.

10. Teledisk Format

Akai distributes some of their sound libraries in the Teledisk .TD0 format. Following a variable length header (including several null-terminated comment lines) data blocks from the floppy disk are stored sequentially. In the uncompressed format each 1024 byte block is preceded by 9 bytes of address information with an additional 4 bytes at each track boundary. Any further information on this mysterious format would be welcomed!

11. MESA File Format

The PC Beta release of MESA uses a 'mesa' chunk following the waveform data, containing a copy of the S3000 series sample header:

MESA II for PC does not use a <mesa> chunk, but uses the standard <smpl> chunk for tuning and looping information with sample start and end points stored in a <cue > chunk.

For more information on the WAV file format see Wave Files.

12. S5000/S6000 Sample Format

The S5000 and S6000 can read files produced by earlier samplers, but by default use WAV files on MS-DOS formatted disks. The WAV files saved by operating system version 1.01 use standard chunks but are somewhat unconventional:

RIFF 'WAVE'
<fmt > - Describes mono or stereo 16-bit PCM (plus 2 unused bytes at end)
<fact> - Describes number of sample words (not actually required for PCM)
<smpl> - Tuning and loop information plus 18 bytes of manufacturer specific data
<data> - Waveform data (16-bit signed, interleaved if stereo)


A single loop is supported, with the loop mode held in the manufacturer specific data. The <smpl> chunk is written before the <data> chunk and any other chunks are stripped off by the sampler. To ensure smooth operation filenames should be less than 20 characters with the WAV extension capitalized. The manufacturer specific data (manufacturer 71, product 94) contains the following parameters but can be omitted if not needed:

A loop tuning parameter is also stored in the above structure but is not yet implemented in the sampler operating systems.

13. S5000/S6000 Sample Format

Program files have an .AKP extension and are described at http://burnit.co.uk/AKPspec/ (mirror here). Multi files (multitimbral setups of programs) have an .AKM extension. Both formats are loosely based on the RIFF file format.

14. PC Floppy Drive Programming

Code for the adisk4 program is shows how to re-program the floppy drive for Akai disk access and includes read, write and format functions. Note that the code is primitive both in style and content. The software will work under DOS and Windows 3.x/95/98, but not NT which blocks direct disk access.

Not all PCs can read all Akai disks. Some modern PCs are obviously not as "IBM Compatible" as they should be, but problems can also be caused by the long hard life many Akai floppy drives have had. Some problems can be solved by using a disk formatted in Akai format by the PC rather than the sampler.

15. This Document

This document Copyright ©1995-2000 Paul Kellett (paul.kellett@maxim.abel.co.uk). You may copy and distribute it. If you develop any software based on this information please give him a credit in it (or its documentation) and send him a copy. The information in this document is believed to be correct, though is known to be incomplete and must be used entirely at your own risk.

Links: Paul Kellett's Akai sampler disk and file formats page
Companies: Akai