AllpassPair

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

CODE

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]