Loudspeader overload protection
US5729611A · kind A · utility
Inventor
Key dates
| Filing date | Jan 24, 1997 |
| Grant date | Mar 17, 1998 |
| Priority date | — |
| Expiry date | Jan 24, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/426
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a loudspeaker of the kind in which negative feedback derived by monitoring actual displacement of the loudspeaker's electroacoustic transducer or cone is used to compensate for transducer non-linearities, overload protection is provided by two variable gain amplifiers between the audio input and the power amplifier. One variable gain amplifier is within the feedback loop and the other variable gain amplifier precedes the feedback loop. A detection circuit has two thresholds close to but below the level at which clipping will begin. A first threshold level is about 1.0 dB below and the second threshold level is about 0.5 dB below. A first control signal to reduce the gain of the variable gain amplifier preceding the loop is generated when the first, lower threshold level is exceeded and causes the gain of the amplifier to decrease at a relatively slow rate. A second control signal to reduce the gain of the amplifier within the loop is generated when the higher threshold level is exceeded and reduces the gain of the amplifier within the loop very rapidly so that clipping is avoided. The first and second control signals may each be derived by a threshold amplifier and a charging ci…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.