SAMPLING core based on a 8-bits CPU NEC manages 8 voices polyphony.
The monophonic sampling engine works at 12 bits resolution and relative DAC is a BA9221 (also some BA9201) which is the same found on famous Yamaha DX7 with different frequencies modes:
- from 7,5 kHz for 63 sec. max
- to 40 kHz for 11.75 sec. max
A single sample can be stretched up to a maximum of 6 octaves with famous high-quality Akai interval algorithms; special Warp pitch allows to time-stretch a section.
EDIT a single or more samples must be placed in a keygroup and once mapped, they this make a a program. Each Keygroup features individual parameters such as:
- Midi channel
- zone assignment
- EG amplitude
- LFO amplitude
- VCF cutoff
- velocity switch.
SAMPLE IMPORT it is possible to sample dump handshake over Midi which is NOT compliant to standard SDS protocol and requires special dedicated softwares.
It is also possible also to use the RS-232C parallel port with old communication soft, but I do not have much information about this protocol, but a dedicated software is dedicated for this task PIC.
FILTER non-resonant filter based on a MF6CN a switched capacitor VCF a kind of an hybrid analog-digital offers -12dB/ Oct. slope. The VCF section also features a simple key filter function for keyboard note tracking on octaves.
LFO a single delayed triangle modulator vibrato with special "desync" option emulates natural acoustic vibration feeling.
the LFO is triggered by modulation wheel or assigned to aftertouch.
ENVELOPE based on VCA BA6110 a 4-segments EG amplitude for each sample in keygroup + 1 EG overall amplitude bias for keygroup. The special positional crossfade tracks the amplitude up to +50% toward lower or higher octave.
TECH: a second EG for filer is available when using OS 4.0.
STORAGE floppy disk drive format 3"5 DD 720 Kb capacity.
The disk volumes are formatted at 800 Kb in Akai proprietary file system, thus the file system is not directly MS-DOS compatible, however ome third-party programs handle AKAI file system from PC computers. Today it is possible to replace standard drive with a third part USB floppy emulator like HxC.
OS most common is 1.2 version burnt into EPROM chip which is able to boots higher 4.0 with floppy disk. The lastest OS4 adds more extra features like s900 timestretch, crossfade and a second EG for filter.
*IMPORTANT* the EPROM OS 1.0 does NOT have boot option so new EPROMS are required to access 4.0 by disk. *DOWNLOAD* S900 OS4 BOOTDISK TELEDISK IMAGE*
MAINTENANCE / MODS the inverter NEL-D32-43 power supply gets faulty and creates troubles with backlight; for replacement you can adapt a standard cheap display so do NOT get ripped by guys on Ebay: S900 / S950 displays replacement are STANDARD and cheap.
TECH: Also check out capacitors, bad soldering and click pops, take a look to this nice video tutorial about BAD RAM issues.
inverter NEL-D3243 issues
- 750 Kb sampling RAM (cannot be expanded)
- 32 samples
- 32 programs
- 16 keygroups.
S900 memory board
EDITOR just some old program around:
Soundfiler ST S900 by drumware (ATARI ST) PIC
- Akaisex converts between 12 and 16 bits akai samplers format
(ATARI ST) PIC
Akai ZEROX (ATARI ST) PIC
AKAI S900 EXPANSION BOARDS:
AKAI S900 vs S950 both machines sound the same.
What's the difference between akai s900 and s950? The s950 features a better floppy drive with higher density 1.44 MB, higher sampler rate, optional SCSI and digital interface and memory can be expanded. The S-900 need OS4 for time stretch function and EG2- However the ASK-90 is a must have expansion for analog sequencer and this feature is compatible only to S-900.
AKAI S SERIES RELATED FAMILY OVERVIEW:
VST PLUGIN / SAMPLED VERSION some free samples disk resources and some plugins, however there are no official PLUGIN version of S900 sampler, but some interesting related programs: