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FTC cracking down on amplifier manufacturers?


codewritinfool

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Interesting.  Apparently before 1974 the claims of amplifier performance were all over the place, and just about meaningless other than a very rough guide.  When I started this game in the late 70s, it seemed more standardized with the common "25 watts at less than .04% THD 20 hz to 20 Khz" and this seemed far more reliable.

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Short cut for reading:

 

§ 432.2 
Required disclosures.

Whenever any direct or indirect representation is made of the power output, power band or power frequency response, or distortion characteristics of sound power amplification equipment, the following disclosure shall be made clearly, conspicuously, and more prominently than any other representations or disclosures permitted under this part: The manufacturer's rated minimum sine wave continuous average power output, in watts, per channel (if the equipment is designed to amplify two or more channels simultaneously) at an impedance of 8 ohms, measured with all associated channels fully driven to rated per channel power. Provided, however, when measuring maximum per channel output of self-powered combination speaker systems that employ two or more amplifiers dedicated to different portions of the audio frequency spectrum, such as those incorporated into combination subwoofer-satellite speaker systems, only those channels dedicated to the same audio frequency spectrum should be considered associated channels that need be fully driven simultaneously to rated per channel power.

3. Revise §  432.3(e) to read as follows:

§ 432.3 
Standard test conditions.

* * * * *

(e) Rated power shall be obtainable at all frequencies within the rated power band of 20 Hz to 20 kHz without exceeding 0.1% of total harmonic distortion after input signals at said frequencies have been continuously applied at full rated power for not less than five (5) minutes at the amplifier's auxiliary input, or if not provided, at the phono input. Provided, however, that for amplifiers utilized as a component in a self-powered subwoofer in a self-powered subwoofer-satellite speaker system that employs two or more amplifiers dedicated to different portions of the audio frequency spectrum, the rated power shall be obtainable at all frequencies within the subwoofer amplifier's intended operating bandwidth without exceeding 0.1% of total harmonic distortion after input signals at said frequencies have been continuously applied at full rated power for not less than five (5) minutes at the amplifier's auxiliary input, or if not provided, at the phono input.

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