Complete audio processing system
US4400583A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 10, 1981 |
| Grant date | Aug 23, 1983 |
| Priority date | — |
| Expiry date | Jul 10, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G9/025
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A complete audio processing system of solid state design for providing improvement of audible signals through dynamic compression including an active filter for transient suppression, a gain control, and a plurality of active frequency control stages for selectively controlling internal gain of signals in different frequency bands. Outputs of the frequency control stages are mixed and provided to a compressor stage having an operational amplifier of gain fixed by a DC feedback network. A gain cell provides variable negative feedback. A rectifier circuit measures the average value of the audio input to the compressor stage and controls the gain cell as a function of the average value to provide negative feedback which increases as a function of increase in the level of said input signal. An attenuator receives the output of the operational amplifier and provides an attenuated but dynamically compressed output so that the circuit provides no substantial overall gain but achieves high compression. Optimum achievable compression is indicated by an LED indicator lamp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.