Sound quality improver for headphone sound - simulates normal loudspeaker room reflections using acoustic delay line tubes and mixing amplifiers

摘要

The device improves sound reproduced from e.g. two channels of a stereo system earphones, and uses two inputs coupled to repective miniature loudspeakers. The acoustic signals are transmitted along acoustic tubes to receiver microphones. Each loudspeaker is coupled to both microphones, the tubes acting as delay lines. The two microphone outputs are passed through a respective amplifier, in which the gain is frequency dependent, to respective first summing circuits which also receive the input signal to the associated loudspeaker and a third signal from a phase inverter amplifier of frequency dependent gain. This amplifier receives a signal from a third summing circuit which receives the input signals to the two loudspeakers. The first summing circuits provide the device outputs.