Alesis QS8, QS7 manual Overview, Basic Architecture, QS Polyphony

Overview: Chapter 4

CHAPTER 4

OVERVIEW

BASIC ARCHITECTURE

The QS contains 16 megabytes of Sound ROM which provide digitized acoustic and electronic samples. These samples are organized into 17 sample groups of different types. The groups are:

Piano	String	Noise	Sound FX
Chromatic	Brass	Voice	Rhythm
Organ	Woodwind	Ethnic
Guitar	Synth	Drums
Bass	Wave	Percussion

Several functions (filter, amplitude envelope, pitch envelope, LFO, multiple modulation sources, signal processors, etc.) can be used to process a sample. A Sound is the combination of a sample with its associated processing.

A Program consists of up to four sounds. These sounds can be layered, split over specific keyboard ranges, or selectively overlapped. The QS has a User Bank of 128 Programs that you can modify, plus 4 Preset Banks of 512 Preset Programs that are permanently installed in the QS at the factory (although the Preset Programs can be edited, they must be stored into the User bank to permanently retain your changes). Each Program is linked to its own Effects Patch.

Preset Banks 1-3 and the User bank are organized into 13 Sound Groups of 10 Sounds each, and are spread out among the top-right row of buttons on the front panel (programs 00-09 are pianos, 50-59 are basses, and so on). The GenMIDI bank, however, does not follow this arrangement; it follows the program list of the General MIDI standard.

A Mix consists of up to 16 Programs, each assigned to a specific MIDI channel and one Effect Patch. The QS has 100 Mixes in the User Bank, plus 4 Preset Banks of 400 Preset Mixes. This is extremely useful for multitimbral setups where the QS plays back different sounds on different MIDI channels. Because of its 64 voices and built- in effects, the QS is often the only sound generator needed.

QS POLYPHONY

The QS provides 64-voice polyphony (i.e., how many notes can play at once). If a program uses one sound, up to 64 notes can play at once. Layering two sounds allows for 32-note polyphony and layering four sounds, 16-note polyphony.

Layering is a powerful technique that allows you to build up complex timbres. This is crucial because acoustic instruments have extremely complex, evolving sounds and by comparison, many synths sound static. Being able to layer up to four sounds allows for creating large ensembles (e.g., brass section consisting of alto & tenor sax, trumpet, and trombone) or extremely realistic versions of single instruments. When creating layered Programs, keep polyphony in mind. If all Programs in a Mix use all four available sounds, the QS will quickly run out of voices.

QS7/QS8 Reference Manual 27