| 摘要 |
The susceptibility of compressors, expanders and noise reduction circuits to undue control by signals outside the passband(s) in which the circuits are active is reduced. In a compressor which operates by narrowing the pass-band of a variable filter 22, the conventional feedback control via rectifier 31 and smoothing means 31, 32a, 32b is counteracted by a further signal derived from a wider frequency region by a rectifier 31' and smoothing circuit 32a'. The further signal bucks the main control signal in combining circuit 33. Similar arrangements are disclosed for arrangements using variable gain circuits instead of a variable filter and alternative arrangements use multichannel control signal circuits having limiters with different thresholds whereby the control signal is tailored to achieve like results. All arrangements reduce the circuit response to signal components outside the pass band(s) at high input signal levels. <IMAGE> |
