Audio Dynamics Release Control With an Integration Window
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio dynamics processors, particularly downward expander type noise reduction systems, suffer from audible modulation and ripple in the VCA control signal when handling dissonant chords or notes, leading to undesirable sounds like grumbling or popping, especially with guitar signals.
Innovation Solution
An integration release window is introduced, where the fast time constant signal modifies the slow time constant signal only after dropping by a predefined number of decibels, ensuring smooth transitions and eliminating ripple modulation, by requiring the fast time constant to decay significantly before affecting the slow time constant response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fast time constant filter is used to provide quick release response, then the release speed is improved, but ripple and modulation artifacts are introduced in the VCA control signal
Solution Approach 1:
The patent combines a fast time constant filter and a slow time constant filter in parallel, merging their outputs through a logarithmic converter and summing junction. The fast filter provides quick release response while the slow filter suppresses ripple, and their combined output achieves both fast release and smooth control signal without modulation artifacts.
Solution Approach 2:
The patent creates a composite time constant system by combining fast and slow exponential release circuits with different time constants. This composite structure allows the system to exhibit both fast response characteristics and ripple suppression properties simultaneously, resolving the contradiction between speed and signal quality.
2Object-generated harmful factors
If a slow time constant filter is used to smooth the release response, then ripple and modulation are reduced, but the release speed becomes too slow
Solution Approach 1:
The patent merges the outputs of fast and slow time constant filters through a logarithmic converter and summing junction. The slow filter provides ripple suppression while the fast filter maintains release speed, and their combined effect resolves the contradiction between smoothness and speed.
Solution Approach 2:
The patent applies partial action by having the slow time constant filter operate only during specific phases of the release envelope. The fast filter handles the bulk of the release work while the slow filter provides selective smoothing, allowing the system to achieve both fast release and ripple suppression without requiring the slow filter to operate continuously.
3Adaptability or versatility
If adaptive release response is implemented to handle different note durations, then versatility is improved, but complexity of the control system increases
Solution Approach 1:
The patent implements dynamic adaptability by making the release time constant variable rather than fixed. The system automatically adjusts between fast and slow release characteristics based on the input signal envelope, providing adaptive response to different note durations and playing styles without requiring manual configuration or complex control logic.
Solution Approach 2:
The patent enables the system to self-adjust its release characteristics based on the incoming audio signal. The parallel fast and slow time constant filters automatically interact to provide appropriate release behavior for different input conditions, eliminating the need for external control mechanisms or complex adaptive algorithms.
Data Source
AI summary
An improved dynamics processing control system incorporates an integration release window to virtually eliminate ripple in the final control signal used to control a Voltage Controlled Amplifier in a signal processor. The input audio signal is level detected using a logarithmic level detector and filtered to provide a very fast time constant. The fast release time constant signal is clamped at a maximum level equal to the user defined threshold and filtered by a second filter providing a very long release time constant. The long release time constant is dynamically varied by the fast time constant to provide an adaptive slow time constant. The fast time constant signal modifies the adaptive slow time constant when the difference between the fast time constant and the slow time constant exceeds a predefined integration release window. The integration release window is based on a minimum number of decibels which is larger than the maximum possible ripple in the fast time constant signal. The integration release window tracks the adaptive slow time constant signal to maintain the integration release window over the entire release range of the adaptive slow time constant decay. Once the difference between the fast time constant signal and adaptive slow time constant signal is less than the integration release window, the slow release signal reverts to the un-altered slow time constant release response.