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AllpassPair

Owned by Luis Casarrubias
Feb 09, 2023
2 min read

Overview

Allpass pair for building doubly complementary crossovers

Discussion

This module creates a pair of allpass filters with the special property that their sum and difference from a doubly complementary highpass-lowpass filter pair. When used in conjunction with the Sum and Difference module (available in the BasicAudioFloat32 library) this Allpass Pair module can be used to construct more complex structures such as N-way crossovers and filter banks.

Variables

Properties

Name

Type

Usage

isHidden

Default value

Range

Units

maxOrder

int

const

1

4

Unrestricted

 

type

string*

const

1

[1 x 5]

Unrestricted

 

setMode

int

const

1

0

Unrestricted

 

xoverFreq

float

parameter

0

12000

20:20000

Hz

Rs

float

parameter

0

40

10:100

dB

Pins

Input Pins

Name: in

Description:

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: Ap1

Description:

Data type: float

 

Name: Ap2

Description:

Data type: float

Scratch Pins

Channel count: 1

Block size: 32

Sample rate: 48000

MATLAB Usage

File Name: allpass_pair_subsystem.m

SYS = allpass_pair_subsystem(NAME, ORDER, TYPE, SETMODE) Implements a pair of allpass systems as cascaded biquads. This allpass pair can be combined to form a doubly complementary highpass/lowpass crossover based on the sum and difference of allpass functions. Inputs... NAME name of the module ORDER the desired order of the larger of the two allpass functions. the smaller transfer function will have order 1 less. This guarantees that combined order of the two allpass transfer functions is always odd. (Default = 4) TYPE the two allpass transfer functions combine to form a filter of the desired type - either 'butter', 'ellip', 'cheby1', or 'cheby2'. (Default = 'ellip') SETMODE one of the allpass filters can be disabled. This lets the user select between both, one, or the other being active. Both Enabled (default) = 0 AllPass 1 Only Enabled = 1 AllPass 2 Only Enabled = 2 Ap1 and Ap2 can be combined to form a lowpass/highpass pair that is doubly complementary. For example... (Ap1 + Ap2)/2 : lowpass (Ap1 - Ap2)/2 : highpass Copyright 2015. DSP Concepts, Inc. All Rights Reserved. Author: David Wurtz AudioWeaverModule [This tag makes it appear under awe_help]

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