The Akai S900 is a 8-voice, 12-bit sampler module. It featured a maximum of 11.75 seconds of sample time at its highest sampling rate of 40kHz, or even more with sampling rates as low as 7.5kHz. Memory is set at 750KB and is not upgradable. Editing consisted of eight edit pages (Play, Record, Edit sample, Edit program, MIDI, Utility, Disk, and Master) accessible by pressing one of the eight buttons along the bottom of the good-sized display screen. To the right of these buttons is a numeric keypad, curser control buttons, and a playback button (plays back a sample after recording it). To the right of these are the control wheel, mic and line inputs, input and output level knobs, and trigger input for triggering recording start or play-back.
Editing on the S900 features many of the normal sample operations such as looping, and even crossfade looping in Version 2.0 of the operating system. There is also a few analog-like editing parameters including a filter (non-resonant) controlled by its own ADSR envelope generator, an additional ADSR controlling amplitude, and an LFO. There is also a function called "Warp" which is a very basic envelope controlling pitch, causing the sound to slide up to pitch. Velocity switching of two samples was also available.The S900 is equipped with a mix out, a left/right pair, plus eight separate voice outputs (one for each voice).
Options for the S900 included the ASK90 (a dedicated drum trigger interface which allowed each of the 8 samples to be triggered individually), IB-101 A/S HD interface, and Marion Systems' MS-9c which changed the S900 from 12-bit to 16-bits. When it's successor, the S950, was released, Akai offered a software upgrade for the S900 that added many of the S950's features.
Historically, even more than its predecessor, the S612, the S900, do to its popularity, defined the look, feel, and operating system of Akai samplers to come.