Alesis K2661 FXBus also called Insert FXBus, Aux FX Bus Aux Bus, FX Preset, Algorithm, Size/PAUs

Basic Effects Mode

Terminology

FXBus (also called Insert FXBus)

A signal path with some kind of processing —a delay, reverb, flanger, etc.—on it. It has stereo inputs and outputs, and contains an FX preset that determines the kind of processing to be applied. A studio has four insert FXBuses, each with its own FX preset, as well as a fifth FXBus, known as the Aux bus.

Aux FX Bus (Aux Bus)

A separate bus from the insert FXBuses, which is placed in the signal path after the output of the insert FXBuses, so that it can act as a global processor.

FX Preset

Determines the type of signal processing that is present on an FXBus or the Aux Bus. FX presets consist of an algorithm, plus the settings of the parameters associated with that algorithm. Any number of FX presets can use the same algorithm. The K2661 comes with a large number of FX presets, and you can modify them or create new ones and store them in RAM. Algorithms, however, are stored in ROM, so you can’t change them. Each FXBus and the Aux Bus gets its own FX preset, so up to five FX presets can be active in a studio at a time.

Algorithm

A specific type of signal processing, like a hall reverb, plate reverb, chorus, flanger, pitcher, compressor, or rotary speaker, which is at the core of an FX preset. KDFX comes with a large variety of algorithms, which are stored in ROM, and are not user-definable. Additional algorithms, supplied by Kurzweil, can be loaded in from disk or SmartMedia when they become available. Algorithm parameters (RT60, delay feedback, pitch change, etc.) are user-definable; the K2661 stores the values of those parameters in RAM as part of an FX preset.

Size/PAUs

How big an algorithm is, in terms of how much processing power it needs to operate. Size is measured in Processor Allocation Units, or PAUs. The simplest algorithms require only 1 PAU, while more complex ones require 2, 3, or even 4. The total number of PAUs available to the four insert FXBuses is 4. PAUs can be allocated automatically as FX presets are assigned to FXBuses, or manually by the user. The Aux Bus has its own set of 3 PAUs, which are not shared with the insert FXBuses.

Parameters

Refers to the user-controlled settings for the different characteristics of an algorithm. For example, the user can set the reverb time (RT60) of an algorithm to 3.5s, or the delay feedback of a delay line to 90%, or the dynamic ratio of a compressor to 10:1. Parameters are stored, along with the algorithm they modify, as part of an FX preset. In certain cases, the parameter settings within a studio can be overridden, either using FXMods or bus overrides.

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