1. I have been researching noise reduction during this period and found that Cadillac has active noise reduction. I understand the principle. I would like to ask the wise netizens, who knows what chip this system uses? It is best to have software and PCB layout or schematic diagram. The correct answer will definitely add bonus points. Please note that the question is about the one on the car, not the earphone. I have found the relevant schematic diagram of the earphone.
2. Austria Microelectronics (AMS), a leading supplier of high-performance analog ICs and sensors, recently announced the launch of AS3435 and AS3415 active noise reduction speaker driver chips, paving the way for the development of a new generation of zero-noise stereo headphones. the road. The AS3435 and AS3415 are also the first active noise reduction ICs with integrated bypass switches. AS3435 is mainly used in feedback systems, while AS3415 is mainly used in feedforward systems. These two chips are the first high-frequency noise-canceling speaker drivers and contain the latest ultra-low-noise amplifier with a noise floor of 900nV, which can cancel high-frequency noise when used with a low-noise microphone. These two chips have two excellent audio characteristics: 35mW stereo output power, 0.1 total harmonic distortion plus noise under 32Ω load, and a signal-to-noise ratio of greater than 110dB.
3. There is a difference. In some models (active noise reduction), NAC will be activated when the engine is started, regardless of whether the audio is turned on or not. In some models, the audio must be turned on to activate NAC. However, there is a difference in NAC. The good thing is that it generally cannot be turned off, especially for models that turn on NAC as soon as they are started. It will be very difficult to modify the audio in the future. Adding a subwoofer will produce a very loud buzzing sound. Without modifying the audio, the general car audio is not enough for girls to listen to the music. demand, so if you have this system and want to change the sound system, you have to go to the 4S store to have it removed