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AMAX is an American certification program developed by the Electronic Industries Association (EIA) and the National Association of Broadcasters (NAB) in 1993. This quality control program addressed both consumer receiver developments and air chains of broadcast AM transmission stations. Tuners and receivers offering AMAX Stereo were designed to capture the widest audio frequency response and stereo separation of AM stereo broadcasts, where available.
AMAX Stereo products are not widely available to the public. To qualify for AMAX certification, the AM receivers must have the following features:
- They must have wide audio bandwidth: 7,500 hertz for home and automotive applications and 6,500 hertz for portable radios.
- They must have some form of bandwidth control, either manual or automatic, including at least two bandwidth provisions, such as "narrow" and "wide".
- They must meet receiver standards for low total harmonic distortion and proper NRSC-1 audio de-emphasis curve.
- They must attenuate the inter-station high frequency 10,000 hertz "whistle" sounds.
- They must have provisions for an external AM antenna connection.
- They must be capable of tuning the expanded AM band (up to 1,700 kHz).
- They must meet NRSC-1 receiver standards for audio distortion and audio de-emphasis.
- Home and automotive receivers must have effective noise blanking.
An effective noise blanker is new to home audio products. This AMAX feature actively reduces the noise and interference encountered from monaural and stereo AM stations during degraded reception conditions, such as during a localized lightning storm. A wide range of noises are successfully suppressed and the resulting audio seems almost clean until the noise is so intense, that the blanking approaches full-time. Motorola says that this is believed to be the most effective noise blanking yet offered within the consumer market.
According to the EIA and National Association of Broadcasters, tuners and receivers that are qualified to carry the AMAX stereo certification logo will capture the widest audio frequency response and highest quality stereo separation of AM stereo broadcasts that modern technology can offer. In addition, AMAX tuners and receivers will capture all of the fidelity transmitted from monaural AM stations. Its audio response is more than two octaves greater than a standard AM radio.